Original Research n Emergency
Radiology
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Blunt Splenic Injury: Use of a Multidetector CT–based Splenic Injury Grading System and Clinical Parameters for Triage of Patients at Admission1 Nitima Saksobhavivat, MD Kathirkamanathan Shanmuganathan, MD Hegang H. Chen, PhD Joseph J. DuBose, MD Howard Richard, MD Mansoor Ali Khan, MBBS, MRCS, FRCS, AKC Jay Menaker, MD Stuart E. Mirvis, MD Thomas M. Scalea, MD
1 From the Department of Diagnostic and Therapeutic Radiology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand (N.S.); Department of Diagnostic Radiology and Nuclear Medicine (K.S., H.R., S.E.M.), Department of Epidemiology and Public Health (H.H.C.), and R. Adams Cowley Shock Trauma Center (J.M., T.M.S.), University of Maryland School of Medicine, 22 S Greene St, Baltimore, MD 21201; Department of Cardiothoracic and Vascular Surgery, University of Texas– Houston, Houston, Tex (J.J.D.); and Imperial College Healthcare NHS Trust, St Mary’s Hospital, London, England (M.A.K.). Received May 5, 2014; revision requested June 19; revision received July 18; accepted August 20; final version accepted August 29. Address correspondence to K.S. (e-mail: [email protected]).
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Purpose:
To assess the use of a dual-phase multidetector computed tomography (CT)–based grading system alone and in combination with assessment of clinical parameters at triage of patients with blunt splenic injury for determination of appropriate treatment (observation, splenic artery embolization [SAE], or splenic surgery).
Materials and Methods:
This HIPAA-compliant retrospective study was approved by the institutional review board, and the requirement for informed consent was waived. Between January 2009 and July 2011, 171 hemodynamically stable patients with blunt splenic injury underwent multidetector CT at admission to the hospital. Images were reviewed by applying a multidetector CT– based grading system, and the amount of hemoperitoneum was quantified. Demographic data, vital signs, laboratory values, injury severity score, abbreviated injury severity, final treatment decision, and success of nonsurgical treatment were reviewed. Receiver operating characteristic curves and stepwise logistic regression analyses were performed to determine the optimal parameters for effective triage of patients.
Results:
One hundred seventy one patients with splenic injury underwent multidetector CT. At triage, clinical treatment decisions were made, and patients received either observation (85 of 171 [50%]) or splenic intervention (surgery, 19 of 171 [11%] or splenic angiography, 67 of 171 [39%]). Four patients underwent SAE after unsuccessful observation. Six of 171 (3.5%) other patients received unsuccessful nonsurgical treatment with SAE. No patients who received observation required splenectomy. Areas under the receiver operating characteristic curve (AUCs) showed that the CT grading system was the best individual predictor of successful observation (AUC, 0.95), and stepwise logistic regression analysis results showed that multidetector CT grade and the abbreviated injury scale score (AUC, 0.97; P = .02) were the best combination of variables for selection of patients for observation versus splenic intervention. The combination of abbreviated injury scale score, systolic blood pressure reading, and serum glucose level was the best triage model for decision making between splenectomy and SAE (AUC, 0.84).
Conclusion:
The best individual predictor of successful observation in patients with blunt splenic injury was the CT-based grading system. Multidetector CT grade and abbreviated injury scale score were the best combination of variables for selection of patients for observation versus splenic intervention. RSNA, 2014
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M
ultidetector computed tomography (CT) is the imaging modality of choice to help diagnose splenic injury in hemodynamically stable patients after blunt trauma (1– 3). Laparotomy is the standard of care for patients who are hemodynamically unstable or who have peritonitis (1,3). Most trauma centers use nonsurgical treatment as the standard of care for hemodynamically stable patients (1–4). Splenic artery embolization (SAE) is becoming a widely used and promising option in nonsurgical treatment that improves its success. However, there are no accepted practice guidelines or consensus on selecting adult patients for nonsurgical treatment (1,3,4). Results of prior studies (5–7) suggest that the grade of splenic injury determined on the basis of CT results alone is a poor predictor of successful nonsurgical treatment. Several authors (8–12) have suggested that vascular injuries, including active splenic bleeding and nonbleeding vascular injury such as pseudoaneurysm and arteriovenous fistula, are associated with increased rates of unsuccessful nonsurgical treatment. In 2006, Marmery et al (12) proposed a new CT grading system that incorporated nonbleeding vascular injury and active splenic hemorrhage. By using
Advances in Knowledge nn The multidetector CT–based splenic grading scale score (area under the curve [AUC], 0.947; 95% confidence interval: 0.899, 0.977) was the best individual variable for decision making at triage between observation and splenic intervention in hemodynamically stable patients with blunt splenic injury. nn The combination of multidetector CT splenic grade and abdominal injury severity score (AUC, 0.97) was significantly better for prediction of the clinical course of treatment than was the multidetector CT grading scale alone (0.97 vs 0.947, respectively; confidence interval for the difference between AUCs: 0.0039, 0.0462).
dual-phase multidetector CT, Boscak et al (13) reported on the importance of acquiring both arterial and portal venous phase images to show blunt splenic vascular and parenchymal injuries and to optimize diagnostic performance. A retrospective study was performed to assess the use of a dual-phase multidetector CT–based grading system alone and in combination with assessment of clinical parameters at triage of patients with blunt splenic injury to help in the determination of appropriate treatment.
Materials and Methods Study Group This Health Insurance Portability and Accountability Act–compliant study was approved by the institutional review board, which waived the requirement for informed consent. Review of our trauma registry showed that 240 consecutive adult patients with blunt splenic trauma were admitted to our level 1 trauma institution from January 2009 to July 2011 (Fig 1). A total of 171 hemodynamically stable patients (116 male, 55 female; age range, 16–92 years; mean 6 standard deviation, 42.6 years 6 18.9) fulfilled the inclusion criteria and formed the study group. Inclusion criteria for this study were blunt trauma, age of 18 years or older, and initial multidetector CT examination including both arterial and portal venous phase imaging of the abdomen performed within 24 hours of admission. Exclusion criteria (Fig 1) were splenic intervention before performance of multidetector CT (n = 33), nondual-phase multidetector CT technique (n = 23), and multidetector CT performed more than 24 hours after admission (n = 1). Patients who underwent nontherapeutic Implication for Patient Care nn None of the patients with blunt splenic injury who were selected at triage for treatment with observation on the basis of the multidetector CT–based grading scale received unsuccessful nonsurgical treatment.
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splenic surgery determined at retrospective review by surgeons (n = 4), patients for whom clinical follow-up of splenic injury was unavailable due to death from other injury (n = 7), and patients who left the hospital against medical advice (n = 1) also were excluded.
Multidetector CT Analysis The parameters of the dual-phase multidetector CT technique are shown in Table 1. All CT images of the abdomen and pelvis were retrospectively and independently reviewed by two emergency radiologists (N.S. and K.S., with 3 and 20 years of experience, respectively). For each patient, 3-mm-thick axial and 4-mm-thick sagittal and coronal multiplanar reformatted images (3-mm interval) were reviewed on a picture archiving and communication system (AGFA IMPAX; AGFA Health Care, Greenville, SC). The readers were blinded to the splenic arteriographic reports and the clinical course of the patients, including treatment and outcomes. Splenic injury was graded according to the CT injury grade proposed by Marmery et al (12) (Table 2). Splenic active bleeding and nonbleeding vascular injury (pseudoaneurysms or arteriovenous fistula) were diagnosed according to previously described criteria (12,13). Diagnosis of hemoperitoneum Published online before print 10.1148/radiol.14141060 Content codes: Radiology 2015; 274:702–711 Abbreviations: AIS = abbreviated injury scale AUC = area under the receiver operating characteristic curve CI = confidence interval SAE = splenic artery embolization Author contributions: Guarantors of integrity of entire study, N.S., K.S., M.A.K.; study concepts/study design or data acquisition or data analysis/interpretation, all authors; manuscript drafting or manuscript revision for important intellectual content, all authors; approval of final version of submitted manuscript, all authors; agrees to ensure any questions related to the work are appropriately resolved, all authors; literature research, N.S., K.S., M.A.K.; clinical studies, N.S., K.S., H.R., J.M., S.E.M., T.M.S.; statistical analysis, N.S., K.S., H.H.C., M.A.K., J.M.; and manuscript editing, N.S., K.S., J.J.D., H.R., M.A.K., J.M., S.E.M. Conflicts of interest are listed at the end of this article.
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Figure 1
Figure 1: Chart shows profile of study group. MDCT = multidetector CT
was made by using axial and reformatted images. Estimation of the amount of hemoperitoneum, which was not incorporated in the CT grading system, was retrospectively evaluated on the basis of CT images. The amount of hemoperitoneum was estimated by using two methods: (a) estimation by radiologists of the volume based on the total number of axial images (small, one to five images; moderate, five to 15 images; and large, more than 15 images) on which the blood was visible and (b) a visual semiquantitative method, previously described by Federle et al (14), which involved counting the number of intraperitoneal compartments (perisplenic space, Morison pouch, left and right paracolic gutters, and pelvis) in which the hemoperitoneum was visible.
Outcome Measures Patient outcomes were determined by means of retrospective review of medical records, surgical reports, and 704
angiographic images. The medical records were reviewed by two reviewers, a trauma and surgical critical care physician and a trauma surgeon (J.M. and M.A.K., with 10 and 5 years of experience, respectively) who were blinded to the CT results for injury-specific data, mechanism of injury, surgical intervention, radiologic procedures and interventions, unsuccessful nonsurgical treatment, and mortality. Demographic data, laboratory values, injury severity score, mechanism of injury, trauma and injury severity score, abbreviated injury scale (AIS) score, and admitting physiologic variables were obtained from the trauma registry. The AIS provides standardized terminology to describe injury and is a measurement of severity on a scale of 1–6. The injury severity score is an overall score for patients with multiple injuries. The scores were squared for the three most injured body regions (head, neck, and face; chest, abdomen, and pelvis; and extremity and external) and
added together to provide the injury severity score. The trauma and injury severity score helped in the determination of the probability of survival on the basis of patient age, injury severity score, and revised trauma score. Surgical reports were reviewed by two trauma surgeons (T.M.S. and J.J.D., with 30 and 6 years of experience, respectively) who were blinded to the CT results to determine indications for surgery, severity of splenic injury, and the amount of hemoperitoneum. All splenic arteriograms were retrospectively reviewed by an interventional radiologist (H.R., with 13 years of experience) to determine the presence of active bleeding or nonbleeding vascular injury without the knowledge of multidetector CT interpretation and final outcome. These results were compared with multidetector CT findings.
Definitions and Reference Standard We followed the reference standard for treatment at our level 1 trauma center.
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Table 1
Table 2
Dual-Phase Multidetector CT and Injection Techniques Multidetector CT or Injection Technique Contrast material volume (mL) Iodine (mg/mL) Total injection amount (mL) Injection rate (mL/sec) Saline chase injection rate (mL/sec) Initiation of intravenous injection Arterial phase (sec) Portal venous phase (sec) Region of interest Detector width (mm) Rotation time (sec) Tube voltage setting (kVp) Milliamperage-second setting (mAs) Tube current modulation Scan range Arterial phase Portal venous phase Scan direction
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Whole-Body Multidetector CT
Abdominal and Pelvic Multidetector CT
100 350 50 6, 4 50
100 350 50 6, 4 50
18 70 ... 0.625 0.5 120 350 Attenuation-based dose
... 70 Triggered in ROI* 0.625 0.5 120 350 Attenuation-based dose
Vertex of skull to inferior pubic ramus Diaphragm to iliac crest Craniocaudal with patient lying supine
Diaphragm to inferior pubic ramus Diaphragm to iliac crest Craniocaudal with patient lying supine
Note.—No excretory phase images were acquired routinely. * ROI = region of interest. Upper abdominal aorta threshold was 120 HU.
The multidetector CT–based splenic grading scale proposed by Marmery et al (12) was used to grade blunt splenic injuries. All patients with grade 1 and grade 2 injuries were selected for observation. Diagnostic splenic angiography was performed in all hemodynamically stable patients with grade 3–4 injuries. If there was nonbleeding vascular injury or active bleeding, SAE was performed. SAE also was performed in patients with a shattered spleen, as described by Marmery et al (12) or Bhullar et al (15). Hemodynamic instability was defined as systolic blood pressure lower than 100 mm Hg and pulse rate higher than 120 beats per minute. Ongoing hemorrhage (declining hematocrit value), failure to respond to initial fluid challenge, and hemodynamic instability were considered indications for splenic surgery. The reference standard method used for diagnosis of nonbleeding vascular injury was considered to be splenic arteriography. Splenic arteriograms or
surgical findings were considered the reference standard for splenic active bleeding. Nonsurgical treatment was defined as any therapy other than therapeutic splenic surgery. Splenic intervention included SAE and surgery. Successful observation was defined as the spleen in situ with no need for splenic surgery or SAE when the patient was discharged from the hospital or at the last clinical follow-up examination. Unsuccessful nonsurgical treatment was defined as the need for splenic surgery for splenic bleeding after the patient was selected for nonsurgical treatment.
Statistical Analysis Statistical analysis was performed by using software (SAS version 9.2; SAS Institute, Cary, NC) to determine diagnostic performance with the CT-based grading system and clinical parameters ito assess the need for surgical treatment and splenic intervention. Areas under the receiver operating characteristic curve (AUCs) were generated.
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Multidetector CT–based Splenic Injury Grading System Grade Grade 1
Injury
Subcapsular hematoma thickness Laceration parenchymal depth Parenchymal hematoma diameter Grade 2 Subcapsular hematoma thickness Laceration parenchymal depth Parenchymal hematoma diameter Grade 3 Subcapsular hematoma thickness Laceration parenchymal depth Parenchymal hematoma diameter Splenic capsule disruption Grade 4a Active intraparenchymal and/or subcapsular bleeding Splenic vascular injury (pseudoaneurysm or arteriovenous fistula) Shattered spleen Grade 4b Active intraperitoneal bleeding
Size (cm) ,1 ,1 ,1 1–3 1–3 1–3 .3 .3 .3 ... ...
...
... ...
Note.—Patients with grade 4 injury were candidates for splenic arteriography or surgery. Modified and reprinted with permission from the American Journal of Roentgenology.
Multiple logistic regression analysis was performed to determine which combination of clinical parameters available at admission and CT findings would improve prediction of outcome. The stepwise selection procedure was performed to determine the best combination of variables to discriminate patients requiring splenic intervention from those requiring observation. The test for differences between AUCs was performed by using the nonparametric method described by Delong et al (16). Comparison of patient characteristics was performed by using the Wilcoxon rank-sum test and the Fisher exact test. 705
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Figure 2
Figure 2: Chart shows treatment of patients with splenic injuries stratified by CT grade. FNOM = failure of nonsurgical management, VI = vascular injury, PS = parenchymal staining, SO = successful observation, Rx = treatment.
A weighted k value was calculated to quantify the agreement between two raters. The Pearson correlation coefficient was used to measure linear correlation between two variables (17).
Results The treatment profile of the study group is shown in Figures 1 and 2. A total of 19 patients underwent splenectomy after multidetector CT at admission. In the 17 patients with grade 4 injuries, there were 24 CT examination findings, which included active bleeding in six patients, isolated nonbleeding vascular injury in two patients, a shattered spleen in two patients, and combined injury in seven patients. The combined 706
injuries included active bleeding and nonbleeding vascular injury in three patients, active bleeding and shattered spleen in three patients, and nonbleeding vascular injury and shattered spleen in one patient. Indications for splenic surgery included hemodynamic instability after CT in 12 patients, a large amount of hemoperitoneum in six patients, and ongoing bleeding in one patient. Review of the surgical reports showed that all 17 patients had active splenic hemorrhage with approximately 800–1500 mL of blood intrasurgically, which was an indication that all laparotomy procedures were therapeutic. Two patients with low-grade injuries (grades 1 and 3) also required splenectomy. In the patient with the grade 1 splenic
injury, a moderate amount of free intraperitoneal fluid and small bowel wall thickening caused abdominal pain and hypotension. At surgery, this patient had a splenic hilar vascular injury with a large amount of hemoperitoneum and small-bowel injury that required surgical repair. The active bleeding and hemoperitoneum were not seen on the admission CT images. The indication for splenectomy for the patient with a grade 3 splenic injury was a large hemorrhagic splenic cyst. The other five patients without active bleeding at admission CT developed ongoing bleeding or hypotension from 3 hours to 4 days after the CT examination. Sixty-seven patients were referred for diagnostic splenic arteriography after
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multidetector CT at admission (Figs 1, 2). Splenic artery embolization was performed in 65 patients, and two patients had normal arteriograms and were not subjected to embolization. Embolization was performed in 31 patients for splenic vascular injuries detected at arteriography (pseudoaneurysm, 30; active bleeding, three; and arteriovenous fistulas, one), 14 patients for a shattered spleen, 15 patients with abnormal parenchymal stains due to splenic injury, and five patients with normal splenic arteriograms. All three of the patients with active bleeding also had a pseudoaneurysm. Six patients who underwent embolization (two normal angiograms, one parenchymal staining, two vascular injuries, and one shattered spleen) ultimately required delayed splenectomy for ongoing hemorrhage after unsuccessful nonsurgical treatment. Review of the medical records and splenic arteriographic reports of the 15 patients with parenchymal staining and five patients with normal angiograms did not show the specific indication for performing SAE. Eighty-five patients initially were selected for observation after multidetector CT at admission on the basis of splenic injury grade. Observation was unsuccessful in four patients, and these patients required SAE because follow-up multidetector CT performed 3–9 days after admission showed splenic pseudoaneurysms. Pseudoaneurysms were confirmed at splenic arteriography in three patients and SAE was performed. In one patient, splenic arteriography did not show a pseudoaneurysm, but SAE was performed for ongoing bleeding. None of these patients ultimately required surgical intervention. The clinical follow-up time for the successful nonsurgical treatment group ranged from 1 to 1210 days (median, 31 days). In the 171 readings, there were nine (5.26%) disagreements between the two readers on the grading of splenic injury at multidetector CT (weighted k, 0.95; 95% confidence interval [CI]: 0.93, 0.97) and nine (5.26%) and 17 (9.94%) on determination of volume of hemoperitoneum by means of methods
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Table 3 Volume of Hemoperitoneum and Treatment Outcome according to CT Grade Volume of Hemoperitoneum and Treatment Outcome Volume of hemoperitoneum Moderate or large volume of hemoperitoneum At least three compartments of hemoperitoneum Treatment Outcome Successful observation (n = 83) Successfully treated with embolization (n = 63) Required splenectomy (n = 25) Unsuccessful nonsurgical treatement (n = 6)
CT Grade 1 (n = 40)
CT Grade 2 (n = 25)
CT Grade 3 (n = 44)
CT Grade 4a (n = 46)
CT Grade 4b (n = 16)
10 (25)
2 (8)
27 (61)
32 (70)
16 (100)
7 (18)
0 (0)
20 (45)
26 (57)
13 (81)
37 (92.5) 2 (5)
22 (88) 3 (12)
22 (50) 18 (41)
2 (4) 37 (80)
0 (0) 3 (19)
1 (2.5) 0
0 (0) 0
4 (9) 3 (6.8)
7 (15) 1 (2.2)
13 (81) 2 (12.5)
Note.—Data are number of patients, with percentages in parentheses.
1 and 2, respectively (weighted k, 0.95 [95% CI: 0.92, 0.98] and 0.95 [95% CI: 0.93, 0.97], respectively). The two readers reached a consensus for the cases for which there were discrepancies by reviewing the cases together for the final statistical analysis. Table 3 shows final treatment outcomes of the 171 patients and estimated volume of hemoperitoneum stratified by CT grade. A moderate correlation between CT grade and estimated volume of hemoperitoneum was observed (Pearson r = 0.50, P , .0001). There was a strong correlation between the two methods used to estimate the volume of hemoperitoneum that was seen on CT images (Pearson r = 0.95, P , .0001). Figure 2 shows treatment of patients with blunt splenic injuries as stratified according to CT grade. Nonsurgical treatment for patients who were initially selected for either observation or SAE (nonsurgical treatment) was successful in 146 of 152 (96.1%) patients. For patients with CT grades 1–3 splenic injuries, nonsurgical treatment was successful in 104 of 107 (97.2%) patients, with splenic salvage in 104 of 109 (95.4%) patients. For patients with CT grades 4a and 4b splenic injuries, however, nonsurgical treatment was successful in 42 of 45 (93.3%, P = .36) patients, with 40 (64.5%) patients
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treated successfully with SAE and two (3.2%) successfully observed. Table 4 shows the characteristics of patients who underwent successful and unsuccessful nonsurgical treatment. Among the 171 patients in the study, unsuccessful nonsurgical treatment occurred in six of 171 (3.5%) patients requiring splenectomy. Indications for splenectomy were hemodynamic instability (n = 3) and ongoing bleeding (n = 3). In summary, 25 patients required splenectomy, 46 patients required SAE, and 83 were successfully treated without splenic intervention. Seventeen patients (14 patients with parenchymal staining and three patients with normal splenic arteriograms) who underwent SAE without meeting the criteria forappropriate indications were excluded from subgroup analysis of discrimination between patients who needed splenic intervention versus those who were successfully observed. The characteristics of the two subgroups are summarized in Table 3. Table 5 shows the AUCs of each variable for prediction of the need for splenic intervention versus successful observation. Among all variables, the multidetector CT–based grading system had the largest AUC and was the single best predictor of the need 707
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Table 4 Demographic and Clinical Parameters of Successful versus Unsuccessful Nonsurgical Treatment and Splenic Intervention versus Observation Groups Nonsurgical Treatment Parameter Patient parameter Age (y) Male sex* Systolic blood pressure (mm Hg) Mean arterial pressure (mm Hg) Heart rate (beats/min) Respiratory rate (breaths/min) Glucose level (mg/dL) Hematocrit level (%) Lactate level (mg/dL) Creatinine level (mg/dL) Patient grades and scores CT grade CT grade of 4a or 4b* Hemoperitoneum volume Hemoperitoneum compartments Glascow coma scale score Revised trauma score Injury severity score Injury severity score 16* Abdominal AIS score Abdominal AIS score 3* Thoracic AIS score Brain AIS score Trauma and injury severity score A severity characterization of trauma Patient time in hospital (d) Patient time in intensive care unit (d) Mechanism of injury* Motor vehicle collision Motorcycle collision Pedestrian or bicyclist Fall Struck by blunt object
Successful (n = 146) 40 (18–92) 100 (68.49) 136 (78–234) 118 (66–208) 90 (55–151) 20 (10–39) 124 (74–312) 38.7 (18.2–51) 2.3 (0.7–8.1) 0.99 (0.5–6.6)
Treatment Group
Unsuccessful (n = 6)
P Value
Intervention Group (n = 71)
Observation Group (n = 83)
P Value
53.5 (38–64) 4 (66.67) 137.5 (75–164) 116 (68–143) 95.5 (64–132) 23 (16–28) 170.5 (103–350) 34.45 (27.7–39.9) 2.65 (1.1–13.7) 1.02 (0.63–1.26)
.09 ..99 .85 .74 .84 .38 .15 .053 .80 .78
47 (18–88) 50 (70.4) 137 (56–234) 99 (47–182) 93 (52–151) 22 (12–47) 148 (89–350) 37.2 (18.2–51) 2.7 (0.8–13.7) 1.0 (0.5–2.2)
37 (18–88) 54 (65.1) 131 (78–203) 98 (54–136) 91 (55–151) 20 (10–39) 122 (74–294) 39.7 (24.7–48.2) 2.3 (0.7–8.1) 1.0 (0.5–6.6)
.03 .50 .15 .74 .96 .23 .006 .008 .28 .75
3 (1–4b) 42 (28.8) 1 (0–3) 2 (0–5) 15 (3–15) 7.84 (4.09–7.84) 22 (4–50) 108 (73.97) 3 (2–5) 81 (55.48) 3 (0–5) 0 (0–2) 0.970 (0.363–0.996) 0.986 (0.357–0.999) ... ...
3.5 (3–4b) 3 (50) 3 (2–3) 4.5 (2–5) 15 (14–15) 7.84 (3.68–7.84) 23 (9–33) 4 (66.67) 3.5 (3–4) 6 (100) 2.5 (0–4) 0 (0–0) 0.932 (0.849–0.994) 0.983 (0.940–0.992) ... ...
... ... ... ... ...
... ... ... ... ...
.027 .36 .005 .007 .89 .77 .86 .65 .046 .040 .55 .24 .30 .51
... ... ... ... ...
4a (1–4b) 60 (84.5) 2 (0–3) 3 (0–5) 15 (13–15) 7.84 (6.38–7.84) 29 (5–50) 64 (90.1) 4 (2–5) 67 (94.4) 3 (0–5) 0 (0–2) 0.955 (0.493–0.996) 0.982 (0.772–0.999) 7 (3–54) 0 (0–54) 36 (50.7) 5 (7.0) 11 (15.5) 14 (19.7) 5 (7.0)
2 (1–4a) 2 (2.4) 1 (0–3) 1 (0–5) 15 (3–15) 7.84 (4.09–7.84) 21 (4–50) 56 (67.5) 2 (2–4) 25 (30.1) 3 (0–5) 0 (0–1) 0.980 (0.363–0.996) 0.986 (0.357–0.999) 5 (0–34) 0 (0–27) 46 (55.4) 14 (16.9) 7 (8.4) 10 (12.1) 6 (7.2)
,.001 ,.001 ,.001 ,.001 .20 .43 ,.001 .001 ,.001 ,.001 .62 .60 ,.001 .007 .03 .02 .18† ... ... ... ... ...
Note. Unless otherwise indicated, data are medians, with the range in parentheses. * Data are numbers of patients, with percentages in parentheses. †
P values determined by means of analysis of variance.
for splenic intervention, followed by abdominal AIS score. The multidetector CT–based grading system showed the largest AUC compared with those of all clinical severity scores (injury severity score, trauma and injury severity score, a severity characterization of trauma score), with a P value of .0001. There was no significant difference between 708
CT grade and abdominal AIS score (P = .055). CT grade was also a better predictor than estimated volume of hemoperitoneum (P , .0001), vital signs, initial laboratory information, age, and sex. Both methods used to estimate the volume of hemoperitoneum were moderately good predictors of the need for splenic intervention (the number of
axial images vs the number of compartments, 0.78 vs 0.77; P = .35). The stepwise selection procedure was performed to determine the best combination of variables to discriminate which of the 154 patients required splenic intervention and which required observation. For the cohort, the best combination of variables was
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Table 5 AUCs for Variables That Allow Prediction of Treatment Variable CT grade Hemoperitoneum volume Hemoperitoneum compartments Injury severity score Abdominal AIS score Trauma and injury severity score Severity characterization of trauma Systolic blood pressure Diastolic blood pressure Mean arterial pressure Heart rate Respiratory rate Hematocrit Lactate Glucose Age Male sex
Splenic Intervention vs Successful Observation
Splenectomy vs Splenic Artery Embolization
0.947 (0.899, 0.977) 0.778 (0.704, 0.841) 0.766 (0.691, 0.830) 0.715 (0.636, 0.784) 0.893 (0.833, 0.937) 0.674 (0.594, 0.748) 0.626 (0.544, 0.703) 0.567 (0.485, 0.646) 0.585 (0.503, 0.664) 0.515 (0.433, 0.596) 0.502 (0.421, 0.584) 0.556 (0.474, 0.636) 0.623 (0.542, 0.700) 0.551 (0.468, 0.631) 0.630 (0.548, 0.706) 0.600 (0.518, 0.678) 0.527 (0.445, 0.608)
0.667 (0.545, 0.774) 0.703 (0.583, 0.806) 0.706 (0.586, 0.808) 0.650 (0.528, 0.760) 0.740 (0.623, 0.837) 0.635 (0.512, 0.746) 0.598 (0.475, 0.713) 0.711 (0.591, 0.812) 0.713 (0.593, 0.814) 0.733 (0.615, 0.831) 0.578 (0.455, 0.694) 0.574 (0.451, 0.691) 0.563 (0.440, 0.680) 0.595 (0.472, 0.710) 0.675 (0.554, 0.782) 0.506 (0.384, 0.627) 0.550 (0.427, 0.668)
Note.—Data in parentheses are 95% CIs.
CT grade and abdominal AIS score, with an AUC of 0.97, which was significantly better than that for CT grade alone (0.97 vs 0.947; 95% CI for the difference between the AUCs: 0.0039, 0.0462). The CT-based grading system was not the best for allowing discrimination between patients who required SAE and those who required splenic surgery (Table 5), with an AUC of 0.67, with the low limit of the 95% CI approaching 0.5. The best two discriminators were the abdominal AIS score (AUC, 0.74) and mean arterial pressure (AUC, 0.73). However, according to pairwise comparison results, none of the covariates gave significantly different AUCs compared with those of the CT-based grading system (P . .05). The stepwise logistic regression analysis showed that the best combination of variables was abdominal AIS score, systolic blood pressure reading at admission, and serum glucose level for discrimination between patients who required SAE and those who required surgery, with an AUC of 0.84, which was significantly better than that of the
abdominal AIS score alone (0.84 vs 0.74, 95% CI for the difference between the AUCs: (0.0135, 0.1942).
Discussion The results of this single-institution retrospective study showed that the CT-based splenic injury grading system proposed by Marmery et al (12) was the single best predictor of treatment success (observation or splenic intervention) in patients with blunt splenic injury. In our study, we found that most of the clinical parameters used as variables were typically available at patient admission, and that the CT grading scale was significantly (P , .0001) better than all clinical parameters except abdominal AIS score. The outcome measures based on the CT grades reported in this study are similar to results of prior single- and multi-institutional studies (4,18–21). The excellent performance of CT compared with clinical parameters in this study can be attributed not only to its ability to provide detailed description of the anatomic disruption to the splenic parenchyma but also to its ability to show important
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well-recognized splenic vascular lesions (active bleeding and nonbleeding vascular injury), a leading cause of unsuccessful nonsurgical treatment (2,8,10–13,15,22–24). Demonstration of any splenic vascular lesions results in upgrading to a grade 4 injury. Authors of most studies (2,4,8–12,15,23,24) agree with the recommendations of the grading system (ie, that all grade 4 injuries require splenic surgery or SAE to prevent unsuccessful nonsurgical treatment). In our study, all patients with grade 4 injury who were selected for laparotomy underwent therapeutic splenectomy. The surgical reports showed the presence of splenic hemorrhage and a large volume of hemoperitoneum (800–1500 mL of blood) at surgery, showing that the CT findings correlated well with clinical deterioration and splenic hemorrhage. Another reason for the high level of performance with the CT-based grading system can be attributed to the acquisition of arterial and portal venous phase images to evaluate solid organs. Authors of recent studies (13,23) have reported that a substantial number of nonbleeding vascular injuries are only seen on arterial phase images and are missed if only portal venous and excretory phase imaging is performed (13,23). Acquiring images that increase the conspicuity of both splenic active bleeding and nonbleeding vascular injury is essential to assess the true extent of anatomic disruption of the splenic parenchyma and vasculature, to grade the severity of injury accurately, and to aid important clinical decision making. Authors of prior studies (5,6,26) reported poor performance of CT for prediction of the need for intervention. These retrospective studies did not include the acquisition of arterial phase images and used pathologic or surgical reports to verify only parenchymal disruption or active bleeding but not nonbleeding vascular injury. Unlike authors of prior studies, we used splenic arteriography as the reference standard for diagnosis of all nonbleeding vascular injury, and this helped with accurate assessment of CT results at triage. Demonstration of active bleeding is time sensitive in many cases, because it 709
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can be seen at both the arterial and delayed phase if the images are acquired when they occur (13,23). Treatment does not differ if the bleeding is seen during both phases or only during the delayed phase (23). In our study, only one patient with active bleeding was not diagnosed at dual-phase imaging. A splenic hilar vessel injury was found at surgery to be the cause for the bleeding and should have been visualized on either arterial or portal venous phase images. Most likely, the injured vessel was in spasm at the time when the images were acquired. There is no consensus among trauma centers on the optimal treatment of hemodynamically stable adult patients with varying degrees of splenic injury (1,3,25,27,28). Clinical decision making to determine the need for observation, SAE, or splenectomy for hemodynamically stable patients with blunt splenic injury is not solely based on the severity as determined with the CT injury scale. Multiple clinical variables that help predict clinical progression, hemodynamic measurements, associated injuries, and clinical examination are taken into consideration. Stepwise multiple logistic regression analysis results showed that the best combination of variables that allows clinical decision making between observation and splenic intervention was CT grade and abdominal AIS score. We also found that considering these variables was significantly better than decision making on the basis of CT grade alone (0.97 vs 0.947; 95% CI for the difference between the AUCs: 0.0039, 0.0462). All patients selected for observation underwent successful nonsurgical treatment. These variables may be used at patient admission to develop a simple prediction rule to use in clinical algorithms. SAE is becoming an adjunct to observation for improvement of successful nonsurgical treatment, especially in patients at high risk who have high-grade splenic injuries and have active bleeding and nonbleeding vascular injury (2,8,11,15,19,21). Bhullar et al (15) suggest that, to reduce unsuccessful nonsurgical treatment 710
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after SAE, it is important to perform embolization routinely in all patients with high-grade splenic injuries in the absence of a contrast blush on images, because splenic arteriography does not allow exclusion of vascular injuries. In our study, all patients with shattered spleens underwent SAE. The rate of unsuccessful nonsurgical treatment for the group of patients selected for planned nonsurgical treatment was 3.5%, which was better than the rates of 4%–12% reported in prior singleand multi-institutional studies (4,18– 20). The best single discriminator of patients who required SAE from those who required splenic surgery was the abdominal AIS score. Stepwise multiple logistic regression analysis results showed that abdominal AIS score, systolic blood pressure reading at admission, and serum glucose level were the best combination of variables to discriminate between the two groups. Our study had limitations. First, this was a retrospective, single-institution study, and because of this, the influence of physical findings on treatment was not taken into consideration. We used semiquantitative methods to estimate the amount of hemoperitoneum. Not all patients undergoing SAE were included in the subgroup analysis because documentation of valid reasons for SAE was not always available. In conclusion, our study results showed that a multidetector CT–based splenic grading scale was the best individual variable for decision making between observation and splenic intervention at triage of hemodynamically stable patients with blunt splenic injury. None of the patients who were determined to require observation and for whom the grading system was used at triage received unsuccessful nonsurgical treatment. The best combination of variables used to discriminate patients who required SAE from those who required splenic surgery were abdominal AIS score, systolic blood pressure reading at admission, and serum glucose level. Disclosures of Conflicts of Interest: N.S. disclosed no relevant relationships. K.S. disclosed no relevant relationships. H.H.C. disclosed no relevant relationships. J.J.D. disclosed no rel-
evant relationships. H.R. disclosed no relevant relationships. M.A.K. disclosed no relevant relationships. J.M. disclosed no relevant relationships. S.E.M. disclosed no relevant relationships. T.M.S. disclosed no relevant relationships.
References 1. Stassen NA, Bhullar I, Cheng JD, et al. Selective nonoperative management of blunt splenic injury: an Eastern Association for the Surgery of Trauma practice management guideline. J Trauma Acute Care Surg 2012;73(5 Suppl 4):S294–S300. 2. Marmery H, Shanmuganathan K, Mirvis SE, et al. Correlation of multidetector CT findings with splenic arteriography and surgery: prospective study in 392 patients. J Am Coll Surg 2008;206(4):685–693. 3. Olthof DC, van der Vlies CH, Joosse P, et al. Consensus strategies for the nonoperative management of patients with blunt splenic injury: a Delphi study. J Trauma Acute Care Surg 2013;74(6):1567–1574. 4. Bhangu A, Nepogodiev D, Lal N, Bowley DM. Meta-analysis of predictive factors and outcomes for failure of non-operative management of blunt splenic trauma. Injury 2012;43(9):1337–1346. 5. Carr JA, Roiter C, Alzuhaili A. Correlation of operative and pathological injury grade with computed tomographic grade in the failed nonoperative management of blunt splenic trauma. Eur J Trauma Emerg Surg 2012; 38(4):433–438. 6. Cohn SM, Arango JI, Myers JG, et al. Computed tomography grading systems poorly predict the need for intervention after spleen and liver injuries. Am Surg 2009;75(2): 133–139. 7. Moore EE, Cogbill TH, Jurkovich GJ, Shackford SR, Malangoni MA, Champion HR. Organ injury scaling: spleen and liver (1994 revision). J Trauma 1995;38(3):323–324. 8. Schurr MJ, Fabian TC, Gavant M, et al. Management of blunt splenic trauma: computed tomographic contrast blush predicts failure of nonoperative management. J Trauma 1995;39(3):507–512; discussion 512–513. 9. Shanmuganathan K, Mirvis SE, Boyd-Kranis R, Takada T, Scalea TM. Nonsurgical management of blunt splenic injury: use of CT criteria to select patients for splenic arteriography and potential endovascular therapy. Radiology 2000;217(1):75–82. 10. Thompson BE, Munera F, Cohn SM, et al. Novel computed tomography scan scoring system predicts the need for intervention af-
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more correlated receiver operating characteristic curves: a nonparametric approach. Biometrics 1988;44(3):837–845.
ter splenic injury. J Trauma 2006;60(5):1083– 1086. 11. Anderson SW, Varghese JC, Lucey BC, Burke PA, Hirsch EF, Soto JA. Blunt splenic trauma: delayed-phase CT for differentiation of active hemorrhage from contained vascular injury in patients. Radiology 2007;243(1): 88–95. 12. Marmery H, Shanmuganathan K, Alexan der MT, Mirvis SE. Optimization of selection for nonoperative management of blunt splenic injury: comparison of MDCT grading systems. AJR Am J Roentgenol 2007;189(6): 1421–1427. 13. Boscak AR, Shanmuganathan K, Mirvis SE, et al. Optimizing trauma multidetector CT protocol for blunt splenic injury: need for arterial and portal venous phase scans. Radiology 2013;268(1):79–88. 14. Federle MP, Jeffrey RB Jr. Hemoperitoneum studied by computed tomography. Radiology 1983;148(1):187–192. 15. Bhullar IS, Frykberg ER, Tepas JJ 3rd, Siragusa D, Loper T, Kerwin AJ. At first blush: absence of computed tomography contrast extravasation in Grade IV or V adult blunt splenic trauma should not preclude angioembolization. J Trauma Acute Care Surg 2013;74(1):105–111; discussion 111–112. 16. DeLong ER, DeLong DM, Clarke-Pearson DL. Comparing the areas under two or
17. Fleiss JL. Statistical methods for rates and proportions. New York, NY: Wiley, 1973; 213–234. 18. Peitzman AB, Heil B, Rivera L, et al. Blunt splenic injury in adults: Multi-institutional Study of the Eastern Association for the Surgery of Trauma. J Trauma 2000;49(2):177– 187; discussion 187–189. 19. Bhullar IS, Frykberg ER, Siragusa D, et al. Selective angiographic embolization of blunt splenic traumatic injuries in adults decreases failure rate of nonoperative management. J Trauma Acute Care Surg 2012;72(5):1127– 1134. 20. Weinberg JA, Lockhart ME, Parmar AD, et al. Computed tomography identification of latent pseudoaneurysm after blunt splenic injury: pathology or technology? J Trauma 2010;68(5):1112–1116. 21. Requarth JA, D’Agostino RB Jr, Miller PR. Nonoperative management of adult blunt splenic injury with and without splenic artery embolotherapy: a meta-analysis. J Trauma 2011;71(4):898–903; discussion 903. 22. Olthof DC, van der Vlies CH, Scheerder MJ, et al. Reliability of injury grading systems for patients with blunt splenic trauma. Injury 2014;45(1):146–150.
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23. Uyeda JW, LeBedis CA, Penn DR, Soto JA, Anderson SW. Active hemorrhage and vascular injuries in splenic trauma: utility of the arterial phase in multidetector CT. Radiology 2014;270(1):99–106. 24. Omert LA, Salyer D, Dunham CM, Porter J, Silva A, Protetch J. Implications of the “contrast blush” finding on computed tomographic scan of the spleen in trauma. J Trauma 2001;51(2):272–277; discussion 277–278. 25. Harbrecht BG, Ko SH, Watson GA, For sythe RM, Rosengart MR, Peitzman AB. Angiography for blunt splenic trauma does not improve the success rate of nonoperative management. J Trauma 2007;63(1):44–49. 26. Barquist ES, Pizano LR, Feuer W, et al. Inter- and intrarater reliability in computed axial tomographic grading of splenic injury: why so many grading scales? J Trauma 2004;56(2):334–338. 27. Zarzaur BL, Kozar RA, Fabian TC, Coim bra R. A survey of American Association for the Surgery of Trauma member practices in the management of blunt splenic injury. J Trauma 2011;70(5):1026–1031. 28. Fata P, Robinson L, Fakhry SM. A survey of EAST member practices in blunt splenic injury: a description of current trends and opportunities for improvement. J Trauma 2005;59(4):836–841; discussion 841–842.
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Blunt Splenic Injury: Use of a Multidetector CT–based Splenic Injury Grading System and Clinical Parameters for Triage of Patients at Admission1 Nitima Saksobhavivat, MD Kathirkamanathan Shanmuganathan, MD Hegang H. Chen, PhD Joseph J. DuBose, MD Howard Richard, MD Mansoor Ali Khan, MBBS, MRCS, FRCS, AKC Jay Menaker, MD Stuart E. Mirvis, MD Thomas M. Scalea, MD
1 From the Department of Diagnostic and Therapeutic Radiology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand (N.S.); Department of Diagnostic Radiology and Nuclear Medicine (K.S., H.R., S.E.M.), Department of Epidemiology and Public Health (H.H.C.), and R. Adams Cowley Shock Trauma Center (J.M., T.M.S.), University of Maryland School of Medicine, 22 S Greene St, Baltimore, MD 21201; Department of Cardiothoracic and Vascular Surgery, University of Texas– Houston, Houston, Tex (J.J.D.); and Imperial College Healthcare NHS Trust, St Mary’s Hospital, London, England (M.A.K.). Received May 5, 2014; revision requested June 19; revision received July 18; accepted August 20; final version accepted August 29. Address correspondence to K.S. (e-mail: [email protected]).
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Purpose:
To assess the use of a dual-phase multidetector computed tomography (CT)–based grading system alone and in combination with assessment of clinical parameters at triage of patients with blunt splenic injury for determination of appropriate treatment (observation, splenic artery embolization [SAE], or splenic surgery).
Materials and Methods:
This HIPAA-compliant retrospective study was approved by the institutional review board, and the requirement for informed consent was waived. Between January 2009 and July 2011, 171 hemodynamically stable patients with blunt splenic injury underwent multidetector CT at admission to the hospital. Images were reviewed by applying a multidetector CT– based grading system, and the amount of hemoperitoneum was quantified. Demographic data, vital signs, laboratory values, injury severity score, abbreviated injury severity, final treatment decision, and success of nonsurgical treatment were reviewed. Receiver operating characteristic curves and stepwise logistic regression analyses were performed to determine the optimal parameters for effective triage of patients.
Results:
One hundred seventy one patients with splenic injury underwent multidetector CT. At triage, clinical treatment decisions were made, and patients received either observation (85 of 171 [50%]) or splenic intervention (surgery, 19 of 171 [11%] or splenic angiography, 67 of 171 [39%]). Four patients underwent SAE after unsuccessful observation. Six of 171 (3.5%) other patients received unsuccessful nonsurgical treatment with SAE. No patients who received observation required splenectomy. Areas under the receiver operating characteristic curve (AUCs) showed that the CT grading system was the best individual predictor of successful observation (AUC, 0.95), and stepwise logistic regression analysis results showed that multidetector CT grade and the abbreviated injury scale score (AUC, 0.97; P = .02) were the best combination of variables for selection of patients for observation versus splenic intervention. The combination of abbreviated injury scale score, systolic blood pressure reading, and serum glucose level was the best triage model for decision making between splenectomy and SAE (AUC, 0.84).
Conclusion:
The best individual predictor of successful observation in patients with blunt splenic injury was the CT-based grading system. Multidetector CT grade and abbreviated injury scale score were the best combination of variables for selection of patients for observation versus splenic intervention. RSNA, 2014
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ultidetector computed tomography (CT) is the imaging modality of choice to help diagnose splenic injury in hemodynamically stable patients after blunt trauma (1– 3). Laparotomy is the standard of care for patients who are hemodynamically unstable or who have peritonitis (1,3). Most trauma centers use nonsurgical treatment as the standard of care for hemodynamically stable patients (1–4). Splenic artery embolization (SAE) is becoming a widely used and promising option in nonsurgical treatment that improves its success. However, there are no accepted practice guidelines or consensus on selecting adult patients for nonsurgical treatment (1,3,4). Results of prior studies (5–7) suggest that the grade of splenic injury determined on the basis of CT results alone is a poor predictor of successful nonsurgical treatment. Several authors (8–12) have suggested that vascular injuries, including active splenic bleeding and nonbleeding vascular injury such as pseudoaneurysm and arteriovenous fistula, are associated with increased rates of unsuccessful nonsurgical treatment. In 2006, Marmery et al (12) proposed a new CT grading system that incorporated nonbleeding vascular injury and active splenic hemorrhage. By using
Advances in Knowledge nn The multidetector CT–based splenic grading scale score (area under the curve [AUC], 0.947; 95% confidence interval: 0.899, 0.977) was the best individual variable for decision making at triage between observation and splenic intervention in hemodynamically stable patients with blunt splenic injury. nn The combination of multidetector CT splenic grade and abdominal injury severity score (AUC, 0.97) was significantly better for prediction of the clinical course of treatment than was the multidetector CT grading scale alone (0.97 vs 0.947, respectively; confidence interval for the difference between AUCs: 0.0039, 0.0462).
dual-phase multidetector CT, Boscak et al (13) reported on the importance of acquiring both arterial and portal venous phase images to show blunt splenic vascular and parenchymal injuries and to optimize diagnostic performance. A retrospective study was performed to assess the use of a dual-phase multidetector CT–based grading system alone and in combination with assessment of clinical parameters at triage of patients with blunt splenic injury to help in the determination of appropriate treatment.
Materials and Methods Study Group This Health Insurance Portability and Accountability Act–compliant study was approved by the institutional review board, which waived the requirement for informed consent. Review of our trauma registry showed that 240 consecutive adult patients with blunt splenic trauma were admitted to our level 1 trauma institution from January 2009 to July 2011 (Fig 1). A total of 171 hemodynamically stable patients (116 male, 55 female; age range, 16–92 years; mean 6 standard deviation, 42.6 years 6 18.9) fulfilled the inclusion criteria and formed the study group. Inclusion criteria for this study were blunt trauma, age of 18 years or older, and initial multidetector CT examination including both arterial and portal venous phase imaging of the abdomen performed within 24 hours of admission. Exclusion criteria (Fig 1) were splenic intervention before performance of multidetector CT (n = 33), nondual-phase multidetector CT technique (n = 23), and multidetector CT performed more than 24 hours after admission (n = 1). Patients who underwent nontherapeutic Implication for Patient Care nn None of the patients with blunt splenic injury who were selected at triage for treatment with observation on the basis of the multidetector CT–based grading scale received unsuccessful nonsurgical treatment.
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splenic surgery determined at retrospective review by surgeons (n = 4), patients for whom clinical follow-up of splenic injury was unavailable due to death from other injury (n = 7), and patients who left the hospital against medical advice (n = 1) also were excluded.
Multidetector CT Analysis The parameters of the dual-phase multidetector CT technique are shown in Table 1. All CT images of the abdomen and pelvis were retrospectively and independently reviewed by two emergency radiologists (N.S. and K.S., with 3 and 20 years of experience, respectively). For each patient, 3-mm-thick axial and 4-mm-thick sagittal and coronal multiplanar reformatted images (3-mm interval) were reviewed on a picture archiving and communication system (AGFA IMPAX; AGFA Health Care, Greenville, SC). The readers were blinded to the splenic arteriographic reports and the clinical course of the patients, including treatment and outcomes. Splenic injury was graded according to the CT injury grade proposed by Marmery et al (12) (Table 2). Splenic active bleeding and nonbleeding vascular injury (pseudoaneurysms or arteriovenous fistula) were diagnosed according to previously described criteria (12,13). Diagnosis of hemoperitoneum Published online before print 10.1148/radiol.14141060 Content codes: Radiology 2015; 274:702–711 Abbreviations: AIS = abbreviated injury scale AUC = area under the receiver operating characteristic curve CI = confidence interval SAE = splenic artery embolization Author contributions: Guarantors of integrity of entire study, N.S., K.S., M.A.K.; study concepts/study design or data acquisition or data analysis/interpretation, all authors; manuscript drafting or manuscript revision for important intellectual content, all authors; approval of final version of submitted manuscript, all authors; agrees to ensure any questions related to the work are appropriately resolved, all authors; literature research, N.S., K.S., M.A.K.; clinical studies, N.S., K.S., H.R., J.M., S.E.M., T.M.S.; statistical analysis, N.S., K.S., H.H.C., M.A.K., J.M.; and manuscript editing, N.S., K.S., J.J.D., H.R., M.A.K., J.M., S.E.M. Conflicts of interest are listed at the end of this article.
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Figure 1
Figure 1: Chart shows profile of study group. MDCT = multidetector CT
was made by using axial and reformatted images. Estimation of the amount of hemoperitoneum, which was not incorporated in the CT grading system, was retrospectively evaluated on the basis of CT images. The amount of hemoperitoneum was estimated by using two methods: (a) estimation by radiologists of the volume based on the total number of axial images (small, one to five images; moderate, five to 15 images; and large, more than 15 images) on which the blood was visible and (b) a visual semiquantitative method, previously described by Federle et al (14), which involved counting the number of intraperitoneal compartments (perisplenic space, Morison pouch, left and right paracolic gutters, and pelvis) in which the hemoperitoneum was visible.
Outcome Measures Patient outcomes were determined by means of retrospective review of medical records, surgical reports, and 704
angiographic images. The medical records were reviewed by two reviewers, a trauma and surgical critical care physician and a trauma surgeon (J.M. and M.A.K., with 10 and 5 years of experience, respectively) who were blinded to the CT results for injury-specific data, mechanism of injury, surgical intervention, radiologic procedures and interventions, unsuccessful nonsurgical treatment, and mortality. Demographic data, laboratory values, injury severity score, mechanism of injury, trauma and injury severity score, abbreviated injury scale (AIS) score, and admitting physiologic variables were obtained from the trauma registry. The AIS provides standardized terminology to describe injury and is a measurement of severity on a scale of 1–6. The injury severity score is an overall score for patients with multiple injuries. The scores were squared for the three most injured body regions (head, neck, and face; chest, abdomen, and pelvis; and extremity and external) and
added together to provide the injury severity score. The trauma and injury severity score helped in the determination of the probability of survival on the basis of patient age, injury severity score, and revised trauma score. Surgical reports were reviewed by two trauma surgeons (T.M.S. and J.J.D., with 30 and 6 years of experience, respectively) who were blinded to the CT results to determine indications for surgery, severity of splenic injury, and the amount of hemoperitoneum. All splenic arteriograms were retrospectively reviewed by an interventional radiologist (H.R., with 13 years of experience) to determine the presence of active bleeding or nonbleeding vascular injury without the knowledge of multidetector CT interpretation and final outcome. These results were compared with multidetector CT findings.
Definitions and Reference Standard We followed the reference standard for treatment at our level 1 trauma center.
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Table 1
Table 2
Dual-Phase Multidetector CT and Injection Techniques Multidetector CT or Injection Technique Contrast material volume (mL) Iodine (mg/mL) Total injection amount (mL) Injection rate (mL/sec) Saline chase injection rate (mL/sec) Initiation of intravenous injection Arterial phase (sec) Portal venous phase (sec) Region of interest Detector width (mm) Rotation time (sec) Tube voltage setting (kVp) Milliamperage-second setting (mAs) Tube current modulation Scan range Arterial phase Portal venous phase Scan direction
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Whole-Body Multidetector CT
Abdominal and Pelvic Multidetector CT
100 350 50 6, 4 50
100 350 50 6, 4 50
18 70 ... 0.625 0.5 120 350 Attenuation-based dose
... 70 Triggered in ROI* 0.625 0.5 120 350 Attenuation-based dose
Vertex of skull to inferior pubic ramus Diaphragm to iliac crest Craniocaudal with patient lying supine
Diaphragm to inferior pubic ramus Diaphragm to iliac crest Craniocaudal with patient lying supine
Note.—No excretory phase images were acquired routinely. * ROI = region of interest. Upper abdominal aorta threshold was 120 HU.
The multidetector CT–based splenic grading scale proposed by Marmery et al (12) was used to grade blunt splenic injuries. All patients with grade 1 and grade 2 injuries were selected for observation. Diagnostic splenic angiography was performed in all hemodynamically stable patients with grade 3–4 injuries. If there was nonbleeding vascular injury or active bleeding, SAE was performed. SAE also was performed in patients with a shattered spleen, as described by Marmery et al (12) or Bhullar et al (15). Hemodynamic instability was defined as systolic blood pressure lower than 100 mm Hg and pulse rate higher than 120 beats per minute. Ongoing hemorrhage (declining hematocrit value), failure to respond to initial fluid challenge, and hemodynamic instability were considered indications for splenic surgery. The reference standard method used for diagnosis of nonbleeding vascular injury was considered to be splenic arteriography. Splenic arteriograms or
surgical findings were considered the reference standard for splenic active bleeding. Nonsurgical treatment was defined as any therapy other than therapeutic splenic surgery. Splenic intervention included SAE and surgery. Successful observation was defined as the spleen in situ with no need for splenic surgery or SAE when the patient was discharged from the hospital or at the last clinical follow-up examination. Unsuccessful nonsurgical treatment was defined as the need for splenic surgery for splenic bleeding after the patient was selected for nonsurgical treatment.
Statistical Analysis Statistical analysis was performed by using software (SAS version 9.2; SAS Institute, Cary, NC) to determine diagnostic performance with the CT-based grading system and clinical parameters ito assess the need for surgical treatment and splenic intervention. Areas under the receiver operating characteristic curve (AUCs) were generated.
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Injury
Subcapsular hematoma thickness Laceration parenchymal depth Parenchymal hematoma diameter Grade 2 Subcapsular hematoma thickness Laceration parenchymal depth Parenchymal hematoma diameter Grade 3 Subcapsular hematoma thickness Laceration parenchymal depth Parenchymal hematoma diameter Splenic capsule disruption Grade 4a Active intraparenchymal and/or subcapsular bleeding Splenic vascular injury (pseudoaneurysm or arteriovenous fistula) Shattered spleen Grade 4b Active intraperitoneal bleeding
Size (cm) ,1 ,1 ,1 1–3 1–3 1–3 .3 .3 .3 ... ...
...
... ...
Note.—Patients with grade 4 injury were candidates for splenic arteriography or surgery. Modified and reprinted with permission from the American Journal of Roentgenology.
Multiple logistic regression analysis was performed to determine which combination of clinical parameters available at admission and CT findings would improve prediction of outcome. The stepwise selection procedure was performed to determine the best combination of variables to discriminate patients requiring splenic intervention from those requiring observation. The test for differences between AUCs was performed by using the nonparametric method described by Delong et al (16). Comparison of patient characteristics was performed by using the Wilcoxon rank-sum test and the Fisher exact test. 705
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Figure 2
Figure 2: Chart shows treatment of patients with splenic injuries stratified by CT grade. FNOM = failure of nonsurgical management, VI = vascular injury, PS = parenchymal staining, SO = successful observation, Rx = treatment.
A weighted k value was calculated to quantify the agreement between two raters. The Pearson correlation coefficient was used to measure linear correlation between two variables (17).
Results The treatment profile of the study group is shown in Figures 1 and 2. A total of 19 patients underwent splenectomy after multidetector CT at admission. In the 17 patients with grade 4 injuries, there were 24 CT examination findings, which included active bleeding in six patients, isolated nonbleeding vascular injury in two patients, a shattered spleen in two patients, and combined injury in seven patients. The combined 706
injuries included active bleeding and nonbleeding vascular injury in three patients, active bleeding and shattered spleen in three patients, and nonbleeding vascular injury and shattered spleen in one patient. Indications for splenic surgery included hemodynamic instability after CT in 12 patients, a large amount of hemoperitoneum in six patients, and ongoing bleeding in one patient. Review of the surgical reports showed that all 17 patients had active splenic hemorrhage with approximately 800–1500 mL of blood intrasurgically, which was an indication that all laparotomy procedures were therapeutic. Two patients with low-grade injuries (grades 1 and 3) also required splenectomy. In the patient with the grade 1 splenic
injury, a moderate amount of free intraperitoneal fluid and small bowel wall thickening caused abdominal pain and hypotension. At surgery, this patient had a splenic hilar vascular injury with a large amount of hemoperitoneum and small-bowel injury that required surgical repair. The active bleeding and hemoperitoneum were not seen on the admission CT images. The indication for splenectomy for the patient with a grade 3 splenic injury was a large hemorrhagic splenic cyst. The other five patients without active bleeding at admission CT developed ongoing bleeding or hypotension from 3 hours to 4 days after the CT examination. Sixty-seven patients were referred for diagnostic splenic arteriography after
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multidetector CT at admission (Figs 1, 2). Splenic artery embolization was performed in 65 patients, and two patients had normal arteriograms and were not subjected to embolization. Embolization was performed in 31 patients for splenic vascular injuries detected at arteriography (pseudoaneurysm, 30; active bleeding, three; and arteriovenous fistulas, one), 14 patients for a shattered spleen, 15 patients with abnormal parenchymal stains due to splenic injury, and five patients with normal splenic arteriograms. All three of the patients with active bleeding also had a pseudoaneurysm. Six patients who underwent embolization (two normal angiograms, one parenchymal staining, two vascular injuries, and one shattered spleen) ultimately required delayed splenectomy for ongoing hemorrhage after unsuccessful nonsurgical treatment. Review of the medical records and splenic arteriographic reports of the 15 patients with parenchymal staining and five patients with normal angiograms did not show the specific indication for performing SAE. Eighty-five patients initially were selected for observation after multidetector CT at admission on the basis of splenic injury grade. Observation was unsuccessful in four patients, and these patients required SAE because follow-up multidetector CT performed 3–9 days after admission showed splenic pseudoaneurysms. Pseudoaneurysms were confirmed at splenic arteriography in three patients and SAE was performed. In one patient, splenic arteriography did not show a pseudoaneurysm, but SAE was performed for ongoing bleeding. None of these patients ultimately required surgical intervention. The clinical follow-up time for the successful nonsurgical treatment group ranged from 1 to 1210 days (median, 31 days). In the 171 readings, there were nine (5.26%) disagreements between the two readers on the grading of splenic injury at multidetector CT (weighted k, 0.95; 95% confidence interval [CI]: 0.93, 0.97) and nine (5.26%) and 17 (9.94%) on determination of volume of hemoperitoneum by means of methods
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Table 3 Volume of Hemoperitoneum and Treatment Outcome according to CT Grade Volume of Hemoperitoneum and Treatment Outcome Volume of hemoperitoneum Moderate or large volume of hemoperitoneum At least three compartments of hemoperitoneum Treatment Outcome Successful observation (n = 83) Successfully treated with embolization (n = 63) Required splenectomy (n = 25) Unsuccessful nonsurgical treatement (n = 6)
CT Grade 1 (n = 40)
CT Grade 2 (n = 25)
CT Grade 3 (n = 44)
CT Grade 4a (n = 46)
CT Grade 4b (n = 16)
10 (25)
2 (8)
27 (61)
32 (70)
16 (100)
7 (18)
0 (0)
20 (45)
26 (57)
13 (81)
37 (92.5) 2 (5)
22 (88) 3 (12)
22 (50) 18 (41)
2 (4) 37 (80)
0 (0) 3 (19)
1 (2.5) 0
0 (0) 0
4 (9) 3 (6.8)
7 (15) 1 (2.2)
13 (81) 2 (12.5)
Note.—Data are number of patients, with percentages in parentheses.
1 and 2, respectively (weighted k, 0.95 [95% CI: 0.92, 0.98] and 0.95 [95% CI: 0.93, 0.97], respectively). The two readers reached a consensus for the cases for which there were discrepancies by reviewing the cases together for the final statistical analysis. Table 3 shows final treatment outcomes of the 171 patients and estimated volume of hemoperitoneum stratified by CT grade. A moderate correlation between CT grade and estimated volume of hemoperitoneum was observed (Pearson r = 0.50, P , .0001). There was a strong correlation between the two methods used to estimate the volume of hemoperitoneum that was seen on CT images (Pearson r = 0.95, P , .0001). Figure 2 shows treatment of patients with blunt splenic injuries as stratified according to CT grade. Nonsurgical treatment for patients who were initially selected for either observation or SAE (nonsurgical treatment) was successful in 146 of 152 (96.1%) patients. For patients with CT grades 1–3 splenic injuries, nonsurgical treatment was successful in 104 of 107 (97.2%) patients, with splenic salvage in 104 of 109 (95.4%) patients. For patients with CT grades 4a and 4b splenic injuries, however, nonsurgical treatment was successful in 42 of 45 (93.3%, P = .36) patients, with 40 (64.5%) patients
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treated successfully with SAE and two (3.2%) successfully observed. Table 4 shows the characteristics of patients who underwent successful and unsuccessful nonsurgical treatment. Among the 171 patients in the study, unsuccessful nonsurgical treatment occurred in six of 171 (3.5%) patients requiring splenectomy. Indications for splenectomy were hemodynamic instability (n = 3) and ongoing bleeding (n = 3). In summary, 25 patients required splenectomy, 46 patients required SAE, and 83 were successfully treated without splenic intervention. Seventeen patients (14 patients with parenchymal staining and three patients with normal splenic arteriograms) who underwent SAE without meeting the criteria forappropriate indications were excluded from subgroup analysis of discrimination between patients who needed splenic intervention versus those who were successfully observed. The characteristics of the two subgroups are summarized in Table 3. Table 5 shows the AUCs of each variable for prediction of the need for splenic intervention versus successful observation. Among all variables, the multidetector CT–based grading system had the largest AUC and was the single best predictor of the need 707
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Table 4 Demographic and Clinical Parameters of Successful versus Unsuccessful Nonsurgical Treatment and Splenic Intervention versus Observation Groups Nonsurgical Treatment Parameter Patient parameter Age (y) Male sex* Systolic blood pressure (mm Hg) Mean arterial pressure (mm Hg) Heart rate (beats/min) Respiratory rate (breaths/min) Glucose level (mg/dL) Hematocrit level (%) Lactate level (mg/dL) Creatinine level (mg/dL) Patient grades and scores CT grade CT grade of 4a or 4b* Hemoperitoneum volume Hemoperitoneum compartments Glascow coma scale score Revised trauma score Injury severity score Injury severity score 16* Abdominal AIS score Abdominal AIS score 3* Thoracic AIS score Brain AIS score Trauma and injury severity score A severity characterization of trauma Patient time in hospital (d) Patient time in intensive care unit (d) Mechanism of injury* Motor vehicle collision Motorcycle collision Pedestrian or bicyclist Fall Struck by blunt object
Successful (n = 146) 40 (18–92) 100 (68.49) 136 (78–234) 118 (66–208) 90 (55–151) 20 (10–39) 124 (74–312) 38.7 (18.2–51) 2.3 (0.7–8.1) 0.99 (0.5–6.6)
Treatment Group
Unsuccessful (n = 6)
P Value
Intervention Group (n = 71)
Observation Group (n = 83)
P Value
53.5 (38–64) 4 (66.67) 137.5 (75–164) 116 (68–143) 95.5 (64–132) 23 (16–28) 170.5 (103–350) 34.45 (27.7–39.9) 2.65 (1.1–13.7) 1.02 (0.63–1.26)
.09 ..99 .85 .74 .84 .38 .15 .053 .80 .78
47 (18–88) 50 (70.4) 137 (56–234) 99 (47–182) 93 (52–151) 22 (12–47) 148 (89–350) 37.2 (18.2–51) 2.7 (0.8–13.7) 1.0 (0.5–2.2)
37 (18–88) 54 (65.1) 131 (78–203) 98 (54–136) 91 (55–151) 20 (10–39) 122 (74–294) 39.7 (24.7–48.2) 2.3 (0.7–8.1) 1.0 (0.5–6.6)
.03 .50 .15 .74 .96 .23 .006 .008 .28 .75
3 (1–4b) 42 (28.8) 1 (0–3) 2 (0–5) 15 (3–15) 7.84 (4.09–7.84) 22 (4–50) 108 (73.97) 3 (2–5) 81 (55.48) 3 (0–5) 0 (0–2) 0.970 (0.363–0.996) 0.986 (0.357–0.999) ... ...
3.5 (3–4b) 3 (50) 3 (2–3) 4.5 (2–5) 15 (14–15) 7.84 (3.68–7.84) 23 (9–33) 4 (66.67) 3.5 (3–4) 6 (100) 2.5 (0–4) 0 (0–0) 0.932 (0.849–0.994) 0.983 (0.940–0.992) ... ...
... ... ... ... ...
... ... ... ... ...
.027 .36 .005 .007 .89 .77 .86 .65 .046 .040 .55 .24 .30 .51
... ... ... ... ...
4a (1–4b) 60 (84.5) 2 (0–3) 3 (0–5) 15 (13–15) 7.84 (6.38–7.84) 29 (5–50) 64 (90.1) 4 (2–5) 67 (94.4) 3 (0–5) 0 (0–2) 0.955 (0.493–0.996) 0.982 (0.772–0.999) 7 (3–54) 0 (0–54) 36 (50.7) 5 (7.0) 11 (15.5) 14 (19.7) 5 (7.0)
2 (1–4a) 2 (2.4) 1 (0–3) 1 (0–5) 15 (3–15) 7.84 (4.09–7.84) 21 (4–50) 56 (67.5) 2 (2–4) 25 (30.1) 3 (0–5) 0 (0–1) 0.980 (0.363–0.996) 0.986 (0.357–0.999) 5 (0–34) 0 (0–27) 46 (55.4) 14 (16.9) 7 (8.4) 10 (12.1) 6 (7.2)
,.001 ,.001 ,.001 ,.001 .20 .43 ,.001 .001 ,.001 ,.001 .62 .60 ,.001 .007 .03 .02 .18† ... ... ... ... ...
Note. Unless otherwise indicated, data are medians, with the range in parentheses. * Data are numbers of patients, with percentages in parentheses. †
P values determined by means of analysis of variance.
for splenic intervention, followed by abdominal AIS score. The multidetector CT–based grading system showed the largest AUC compared with those of all clinical severity scores (injury severity score, trauma and injury severity score, a severity characterization of trauma score), with a P value of .0001. There was no significant difference between 708
CT grade and abdominal AIS score (P = .055). CT grade was also a better predictor than estimated volume of hemoperitoneum (P , .0001), vital signs, initial laboratory information, age, and sex. Both methods used to estimate the volume of hemoperitoneum were moderately good predictors of the need for splenic intervention (the number of
axial images vs the number of compartments, 0.78 vs 0.77; P = .35). The stepwise selection procedure was performed to determine the best combination of variables to discriminate which of the 154 patients required splenic intervention and which required observation. For the cohort, the best combination of variables was
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Table 5 AUCs for Variables That Allow Prediction of Treatment Variable CT grade Hemoperitoneum volume Hemoperitoneum compartments Injury severity score Abdominal AIS score Trauma and injury severity score Severity characterization of trauma Systolic blood pressure Diastolic blood pressure Mean arterial pressure Heart rate Respiratory rate Hematocrit Lactate Glucose Age Male sex
Splenic Intervention vs Successful Observation
Splenectomy vs Splenic Artery Embolization
0.947 (0.899, 0.977) 0.778 (0.704, 0.841) 0.766 (0.691, 0.830) 0.715 (0.636, 0.784) 0.893 (0.833, 0.937) 0.674 (0.594, 0.748) 0.626 (0.544, 0.703) 0.567 (0.485, 0.646) 0.585 (0.503, 0.664) 0.515 (0.433, 0.596) 0.502 (0.421, 0.584) 0.556 (0.474, 0.636) 0.623 (0.542, 0.700) 0.551 (0.468, 0.631) 0.630 (0.548, 0.706) 0.600 (0.518, 0.678) 0.527 (0.445, 0.608)
0.667 (0.545, 0.774) 0.703 (0.583, 0.806) 0.706 (0.586, 0.808) 0.650 (0.528, 0.760) 0.740 (0.623, 0.837) 0.635 (0.512, 0.746) 0.598 (0.475, 0.713) 0.711 (0.591, 0.812) 0.713 (0.593, 0.814) 0.733 (0.615, 0.831) 0.578 (0.455, 0.694) 0.574 (0.451, 0.691) 0.563 (0.440, 0.680) 0.595 (0.472, 0.710) 0.675 (0.554, 0.782) 0.506 (0.384, 0.627) 0.550 (0.427, 0.668)
Note.—Data in parentheses are 95% CIs.
CT grade and abdominal AIS score, with an AUC of 0.97, which was significantly better than that for CT grade alone (0.97 vs 0.947; 95% CI for the difference between the AUCs: 0.0039, 0.0462). The CT-based grading system was not the best for allowing discrimination between patients who required SAE and those who required splenic surgery (Table 5), with an AUC of 0.67, with the low limit of the 95% CI approaching 0.5. The best two discriminators were the abdominal AIS score (AUC, 0.74) and mean arterial pressure (AUC, 0.73). However, according to pairwise comparison results, none of the covariates gave significantly different AUCs compared with those of the CT-based grading system (P . .05). The stepwise logistic regression analysis showed that the best combination of variables was abdominal AIS score, systolic blood pressure reading at admission, and serum glucose level for discrimination between patients who required SAE and those who required surgery, with an AUC of 0.84, which was significantly better than that of the
abdominal AIS score alone (0.84 vs 0.74, 95% CI for the difference between the AUCs: (0.0135, 0.1942).
Discussion The results of this single-institution retrospective study showed that the CT-based splenic injury grading system proposed by Marmery et al (12) was the single best predictor of treatment success (observation or splenic intervention) in patients with blunt splenic injury. In our study, we found that most of the clinical parameters used as variables were typically available at patient admission, and that the CT grading scale was significantly (P , .0001) better than all clinical parameters except abdominal AIS score. The outcome measures based on the CT grades reported in this study are similar to results of prior single- and multi-institutional studies (4,18–21). The excellent performance of CT compared with clinical parameters in this study can be attributed not only to its ability to provide detailed description of the anatomic disruption to the splenic parenchyma but also to its ability to show important
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well-recognized splenic vascular lesions (active bleeding and nonbleeding vascular injury), a leading cause of unsuccessful nonsurgical treatment (2,8,10–13,15,22–24). Demonstration of any splenic vascular lesions results in upgrading to a grade 4 injury. Authors of most studies (2,4,8–12,15,23,24) agree with the recommendations of the grading system (ie, that all grade 4 injuries require splenic surgery or SAE to prevent unsuccessful nonsurgical treatment). In our study, all patients with grade 4 injury who were selected for laparotomy underwent therapeutic splenectomy. The surgical reports showed the presence of splenic hemorrhage and a large volume of hemoperitoneum (800–1500 mL of blood) at surgery, showing that the CT findings correlated well with clinical deterioration and splenic hemorrhage. Another reason for the high level of performance with the CT-based grading system can be attributed to the acquisition of arterial and portal venous phase images to evaluate solid organs. Authors of recent studies (13,23) have reported that a substantial number of nonbleeding vascular injuries are only seen on arterial phase images and are missed if only portal venous and excretory phase imaging is performed (13,23). Acquiring images that increase the conspicuity of both splenic active bleeding and nonbleeding vascular injury is essential to assess the true extent of anatomic disruption of the splenic parenchyma and vasculature, to grade the severity of injury accurately, and to aid important clinical decision making. Authors of prior studies (5,6,26) reported poor performance of CT for prediction of the need for intervention. These retrospective studies did not include the acquisition of arterial phase images and used pathologic or surgical reports to verify only parenchymal disruption or active bleeding but not nonbleeding vascular injury. Unlike authors of prior studies, we used splenic arteriography as the reference standard for diagnosis of all nonbleeding vascular injury, and this helped with accurate assessment of CT results at triage. Demonstration of active bleeding is time sensitive in many cases, because it 709
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can be seen at both the arterial and delayed phase if the images are acquired when they occur (13,23). Treatment does not differ if the bleeding is seen during both phases or only during the delayed phase (23). In our study, only one patient with active bleeding was not diagnosed at dual-phase imaging. A splenic hilar vessel injury was found at surgery to be the cause for the bleeding and should have been visualized on either arterial or portal venous phase images. Most likely, the injured vessel was in spasm at the time when the images were acquired. There is no consensus among trauma centers on the optimal treatment of hemodynamically stable adult patients with varying degrees of splenic injury (1,3,25,27,28). Clinical decision making to determine the need for observation, SAE, or splenectomy for hemodynamically stable patients with blunt splenic injury is not solely based on the severity as determined with the CT injury scale. Multiple clinical variables that help predict clinical progression, hemodynamic measurements, associated injuries, and clinical examination are taken into consideration. Stepwise multiple logistic regression analysis results showed that the best combination of variables that allows clinical decision making between observation and splenic intervention was CT grade and abdominal AIS score. We also found that considering these variables was significantly better than decision making on the basis of CT grade alone (0.97 vs 0.947; 95% CI for the difference between the AUCs: 0.0039, 0.0462). All patients selected for observation underwent successful nonsurgical treatment. These variables may be used at patient admission to develop a simple prediction rule to use in clinical algorithms. SAE is becoming an adjunct to observation for improvement of successful nonsurgical treatment, especially in patients at high risk who have high-grade splenic injuries and have active bleeding and nonbleeding vascular injury (2,8,11,15,19,21). Bhullar et al (15) suggest that, to reduce unsuccessful nonsurgical treatment 710
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after SAE, it is important to perform embolization routinely in all patients with high-grade splenic injuries in the absence of a contrast blush on images, because splenic arteriography does not allow exclusion of vascular injuries. In our study, all patients with shattered spleens underwent SAE. The rate of unsuccessful nonsurgical treatment for the group of patients selected for planned nonsurgical treatment was 3.5%, which was better than the rates of 4%–12% reported in prior singleand multi-institutional studies (4,18– 20). The best single discriminator of patients who required SAE from those who required splenic surgery was the abdominal AIS score. Stepwise multiple logistic regression analysis results showed that abdominal AIS score, systolic blood pressure reading at admission, and serum glucose level were the best combination of variables to discriminate between the two groups. Our study had limitations. First, this was a retrospective, single-institution study, and because of this, the influence of physical findings on treatment was not taken into consideration. We used semiquantitative methods to estimate the amount of hemoperitoneum. Not all patients undergoing SAE were included in the subgroup analysis because documentation of valid reasons for SAE was not always available. In conclusion, our study results showed that a multidetector CT–based splenic grading scale was the best individual variable for decision making between observation and splenic intervention at triage of hemodynamically stable patients with blunt splenic injury. None of the patients who were determined to require observation and for whom the grading system was used at triage received unsuccessful nonsurgical treatment. The best combination of variables used to discriminate patients who required SAE from those who required splenic surgery were abdominal AIS score, systolic blood pressure reading at admission, and serum glucose level. Disclosures of Conflicts of Interest: N.S. disclosed no relevant relationships. K.S. disclosed no relevant relationships. H.H.C. disclosed no relevant relationships. J.J.D. disclosed no rel-
evant relationships. H.R. disclosed no relevant relationships. M.A.K. disclosed no relevant relationships. J.M. disclosed no relevant relationships. S.E.M. disclosed no relevant relationships. T.M.S. disclosed no relevant relationships.
References 1. Stassen NA, Bhullar I, Cheng JD, et al. Selective nonoperative management of blunt splenic injury: an Eastern Association for the Surgery of Trauma practice management guideline. J Trauma Acute Care Surg 2012;73(5 Suppl 4):S294–S300. 2. Marmery H, Shanmuganathan K, Mirvis SE, et al. Correlation of multidetector CT findings with splenic arteriography and surgery: prospective study in 392 patients. J Am Coll Surg 2008;206(4):685–693. 3. Olthof DC, van der Vlies CH, Joosse P, et al. Consensus strategies for the nonoperative management of patients with blunt splenic injury: a Delphi study. J Trauma Acute Care Surg 2013;74(6):1567–1574. 4. Bhangu A, Nepogodiev D, Lal N, Bowley DM. Meta-analysis of predictive factors and outcomes for failure of non-operative management of blunt splenic trauma. Injury 2012;43(9):1337–1346. 5. Carr JA, Roiter C, Alzuhaili A. Correlation of operative and pathological injury grade with computed tomographic grade in the failed nonoperative management of blunt splenic trauma. Eur J Trauma Emerg Surg 2012; 38(4):433–438. 6. Cohn SM, Arango JI, Myers JG, et al. Computed tomography grading systems poorly predict the need for intervention after spleen and liver injuries. Am Surg 2009;75(2): 133–139. 7. Moore EE, Cogbill TH, Jurkovich GJ, Shackford SR, Malangoni MA, Champion HR. Organ injury scaling: spleen and liver (1994 revision). J Trauma 1995;38(3):323–324. 8. Schurr MJ, Fabian TC, Gavant M, et al. Management of blunt splenic trauma: computed tomographic contrast blush predicts failure of nonoperative management. J Trauma 1995;39(3):507–512; discussion 512–513. 9. Shanmuganathan K, Mirvis SE, Boyd-Kranis R, Takada T, Scalea TM. Nonsurgical management of blunt splenic injury: use of CT criteria to select patients for splenic arteriography and potential endovascular therapy. Radiology 2000;217(1):75–82. 10. Thompson BE, Munera F, Cohn SM, et al. Novel computed tomography scan scoring system predicts the need for intervention af-
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more correlated receiver operating characteristic curves: a nonparametric approach. Biometrics 1988;44(3):837–845.
ter splenic injury. J Trauma 2006;60(5):1083– 1086. 11. Anderson SW, Varghese JC, Lucey BC, Burke PA, Hirsch EF, Soto JA. Blunt splenic trauma: delayed-phase CT for differentiation of active hemorrhage from contained vascular injury in patients. Radiology 2007;243(1): 88–95. 12. Marmery H, Shanmuganathan K, Alexan der MT, Mirvis SE. Optimization of selection for nonoperative management of blunt splenic injury: comparison of MDCT grading systems. AJR Am J Roentgenol 2007;189(6): 1421–1427. 13. Boscak AR, Shanmuganathan K, Mirvis SE, et al. Optimizing trauma multidetector CT protocol for blunt splenic injury: need for arterial and portal venous phase scans. Radiology 2013;268(1):79–88. 14. Federle MP, Jeffrey RB Jr. Hemoperitoneum studied by computed tomography. Radiology 1983;148(1):187–192. 15. Bhullar IS, Frykberg ER, Tepas JJ 3rd, Siragusa D, Loper T, Kerwin AJ. At first blush: absence of computed tomography contrast extravasation in Grade IV or V adult blunt splenic trauma should not preclude angioembolization. J Trauma Acute Care Surg 2013;74(1):105–111; discussion 111–112. 16. DeLong ER, DeLong DM, Clarke-Pearson DL. Comparing the areas under two or
17. Fleiss JL. Statistical methods for rates and proportions. New York, NY: Wiley, 1973; 213–234. 18. Peitzman AB, Heil B, Rivera L, et al. Blunt splenic injury in adults: Multi-institutional Study of the Eastern Association for the Surgery of Trauma. J Trauma 2000;49(2):177– 187; discussion 187–189. 19. Bhullar IS, Frykberg ER, Siragusa D, et al. Selective angiographic embolization of blunt splenic traumatic injuries in adults decreases failure rate of nonoperative management. J Trauma Acute Care Surg 2012;72(5):1127– 1134. 20. Weinberg JA, Lockhart ME, Parmar AD, et al. Computed tomography identification of latent pseudoaneurysm after blunt splenic injury: pathology or technology? J Trauma 2010;68(5):1112–1116. 21. Requarth JA, D’Agostino RB Jr, Miller PR. Nonoperative management of adult blunt splenic injury with and without splenic artery embolotherapy: a meta-analysis. J Trauma 2011;71(4):898–903; discussion 903. 22. Olthof DC, van der Vlies CH, Scheerder MJ, et al. Reliability of injury grading systems for patients with blunt splenic trauma. Injury 2014;45(1):146–150.
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23. Uyeda JW, LeBedis CA, Penn DR, Soto JA, Anderson SW. Active hemorrhage and vascular injuries in splenic trauma: utility of the arterial phase in multidetector CT. Radiology 2014;270(1):99–106. 24. Omert LA, Salyer D, Dunham CM, Porter J, Silva A, Protetch J. Implications of the “contrast blush” finding on computed tomographic scan of the spleen in trauma. J Trauma 2001;51(2):272–277; discussion 277–278. 25. Harbrecht BG, Ko SH, Watson GA, For sythe RM, Rosengart MR, Peitzman AB. Angiography for blunt splenic trauma does not improve the success rate of nonoperative management. J Trauma 2007;63(1):44–49. 26. Barquist ES, Pizano LR, Feuer W, et al. Inter- and intrarater reliability in computed axial tomographic grading of splenic injury: why so many grading scales? J Trauma 2004;56(2):334–338. 27. Zarzaur BL, Kozar RA, Fabian TC, Coim bra R. A survey of American Association for the Surgery of Trauma member practices in the management of blunt splenic injury. J Trauma 2011;70(5):1026–1031. 28. Fata P, Robinson L, Fakhry SM. A survey of EAST member practices in blunt splenic injury: a description of current trends and opportunities for improvement. J Trauma 2005;59(4):836–841; discussion 841–842.
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