Accepted Manuscript A Negative Urinalysis is Associated with a Low Likelihood of Intra-abdominal Injury after Blunt Abdominal Trauma Teresa S. Jones, MD, Robert T. Stovall, MD, Edward L. Jones, MD, Bryan Knepper, BA, Fredric M. Pieracci, MD, Charles J. Fox, MD, Ernest E. Moore, MD, Clay Cothren Burlew, MD PII:
S0002-9610(16)30285-9
DOI:
10.1016/j.amjsurg.2016.05.005
Reference:
AJS 11950
To appear in:
The American Journal of Surgery
Received Date: 27 February 2016 Revised Date:
28 April 2016
Accepted Date: 1 May 2016
Please cite this article as: Jones TS, Stovall RT, Jones EL, Knepper B, Pieracci FM, Fox CJ, Moore EE, Cothren Burlew C, A Negative Urinalysis is Associated with a Low Likelihood of Intra-abdominal Injury after Blunt Abdominal Trauma, The American Journal of Surgery (2016), doi: 10.1016/ j.amjsurg.2016.05.005. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
Teresa S. Jones MD
Edward L. Jones MD Bryan Knepper, BA
SC
Robert T. Stovall MD
RI PT
A Negative Urinalysis is Associated with a Low Likelihood of Intra-abdominal Injury after Blunt Abdominal Trauma
M AN U
Fredric M. Pieracci MD Charles J. Fox MD
Ernest E. Moore MD
TE D
Clay Cothren Burlew MD
EP
Presented at the 2015 Southwestern Surgical Congress Annual Meeting, Monterey CA.
AC C
From the Department of Surgery, Denver Health Medical Center and the University of Colorado School of Medicine, Denver CO
Address correspondence to:
Clay Cothren Burlew, MD FACS Director, Surgical Intensive Care Unit Program Director, SCC and TACS Fellowships Department of Surgery Denver Health Medical Center 777 Bannock Street, MC 0206 Denver, CO 80204 Phone: 303-602-1830 E-Mail: [email protected] 1
ACCEPTED MANUSCRIPT
Abstract Background: The utility of urinalysis to diagnose intra-abdominal (IA) or genitourinary (GU)
significance of urinalysis in the blunt trauma patient
RI PT
injury after blunt trauma remains controversial. The purpose of this study was to determine the
Methods: A retrospective review of patients admitted for blunt abdominal trauma from 2011-
SC
2013.
Results: 1795 patients sustained blunt abdominal trauma: mean age of 44±21 years; mean ISS of
M AN U
13 ±10. 810 patients had a negative urinalysis (45%). Two patients (2/810, 0.2%) had a GU injury and neither required intervention. Thirty-two patients (32/810, 4.0%) had an IA injury, and two (2/810, 0.02%) required intervention. The sensitivity for predicting GU injury requiring intervention was 1 and IA injury requiring intervention was 0.96. Negative predictive values
TE D
were 1 and 0.99
Conclusion: A negative urinalysis correlates with a low risk for GU and IA injury after blunt abdominal trauma. A negative urinalysis should be evaluated prospectively as part of a clinical
AC C
EP
prediction score to rule out injury and avoid unnecessary radiation exposure from CT imaging.
2
ACCEPTED MANUSCRIPT
Key words: urinalysis, hematuria, blunt abdominal trauma, blunt trauma, intra-abdominal,
RI PT
genitourinary
Summary for the Table of Contents
A urinalysis with no hematuria after blunt abdominal trauma is associated with low risk of intra-
SC
abdominal or genitourinary injuries that require intervention/treatment. Clinicians should
consider observation alone in patients with a negative urinalysis and no other indications for
M AN U
abdominal imaging after blunt abdominal trauma. A urinalysis can identify low risk patients, and
AC C
EP
TE D
thus should thus be obtained in all patients who suffer blunt abdominal trauma.
3
ACCEPTED MANUSCRIPT
The presence of hematuria in a trauma patient has been suggested as an indicator for genitourinary (GU) and intra-abdominal (IA) injury. While it is commonly accepted that gross hematuria is a marker for both GU and IA injuries, the significance of microscopic hematuria
RI PT
remains questionable.1-3 In children, a urinalysis with microscopic hematuria >5 RBCs per high powered field correlates with the presence of an IA injury.4,5 In the adult population, however, there is a discrepancy between hematuria and IA injury. A clinical prediction rule developed in
SC
2009 validated microscopic hematuria >25 RBCs per high powered field as predictive of blunt torso trauma in adults.6 In contrast, two studies demonstrated that even macroscopic hematuria
M AN U
was not accurate for predicting injury when utilized in adult patients who had concomitant CT scans.7,8 A more recent publication recommends omission of the urinalysis from routine trauma assessment.9
Suggestions that routine urinalysis can be omitted after blunt abdominal injury may stem
TE D
from the increased use of computed tomography in the evaluation of the trauma patient. Whole body CT scanning has been advocated to reduce morbidity and mortality in blunt trauma patients, however the increasing cost and radiation exposure remains a significant concern.10-12
EP
Identification of patients with a low risk of IA injury may help limit the number of CT scans that are obtained in trauma patients, and obtaining a urinalysis may aid in the identification of such a
AC C
patient cohort.
The purpose of this study was to define the utility of the urinalysis after blunt abdominal
trauma in a large patient population. We hypothesize that the urinalysis would identify a subset of patients who are low risk for GU and IA injury; this patient cohort could potentially be safely observed after blunt abdominal trauma without additional imaging.
4
ACCEPTED MANUSCRIPT
METHODS The Denver Health Medical Center (DHMC) Trauma Registry was queried for all blunt trauma patients between January 2011 and December 2013. DHMC is a state-cerified and
RI PT
American College of Surgeons-verified level I regional trauma center and an intergral teaching facility of the University of Colorado School of Medicine. Patients with a urinalysis within 12 hours of arrival to the emergency department were included in the study population. Patients
SC
with gross hematuria, an initial trauma workup at an outside facility, or no available urinalysis results were excluded. Patient demographics, mechanism of injury, Injury Severity Score (ISS),
M AN U
identified injuries, and need for intervention were recorded. The presence of any red blood cell or hemoglobin in the specimen was considered a positive urinalysis (UA). The sensitivity, specificity, positive and negative predictive values (PPV and NPV respectively) as well as likelihood ratio (LR) of the UA were calculated for all GU and IA
TE D
injuries and those GU and IA injuries that required intervention (surgical or an interventional radiology (IR) procedure). A p < 0.05 was considered statistically significant. The University of
RESULTS
EP
Colorado Multi-Institutional Review Board approved this study.
AC C
There were 3,932 patients evaluated for blunt trauma during the study period and 1,795
(46%) met inclusion criteria. The majority (1140 patients, 64%) were men with a mean age of 44±21 years of age and mean Injury Severity Score of 13±10. The most common mechanisms of injury were motor vehicle collisions in 628 patients (35%), followed by falls (487 patients, 27%), auto-vs-pedestrian collisions (214 patients, 12%) and assaults (171 patients, 10%). Two hundred and six patients (12%) had IA injuries including liver (92 patients, 45%), spleen (79 patients,
5
ACCEPTED MANUSCRIPT
38%) and kidney (45 patients, 22%). Fifty-three patients (24%) with IA injuries required intervention for their injuries: 50 patients went to surgery and three patients were treated with IR procedures. Of these IA injury patients, 10 patients had GU injuries requiring intervention (9
RI PT
patients went to surgery and 1 was treated by interventional radiology).
A negative urinalysis was documented in eight hundred and ten patients (45%). Of these patients, two (0.2%) had GU injuries and neither patient required intervention. There were thirty-
SC
two patients (4%) who had an IA injury and two patients (0.2%) required intervention. (Table 1) A positive urinalysis was documented in nine hundred and eighty five patients (55%). Of
M AN U
these patients, one hundred and seventy four (18%) had an IA injury and 51 patients (29%) required intervention. There were fifty-one patients (5%) who had GU injuries and 10 patients (22%) required intervention.
The sensitivity, specificity, positive and negative predictive values and likelihood ratios
TE D
of the UA after blunt abdominal trauma are reported in Table 2. The urinalysis has a high sensitivity and negative predictive value for IA (0.85 and 0.96 respectively) and GU (0.98 and 0.99 respectively) injuries. The urinalysis is even more sensitive and has a better NPV when it is
EP
used to identify only those patients who require intervention for their IA (0.96 and 0.99 respectively) or GU (1.0 and 1.0 respectively) injuries.
AC C
Patients with defined injuries were compared to the quantification of RBCs in the
urinalysis; this analysis was done to evaluate for a possible threshold RBC value for injury screening. Table 3 demonstrates the number of patients who had quantified microscopic hematuria and those who had injuries. For example, of the patients who had 1-4 red blood cells/high powered field, 7 had GU injuries and 41 had IA injuries. Having the threshold for a positive UA as 5-9 RBCs/hpf would have missed these injuries, which also included 9 patients
6
ACCEPTED MANUSCRIPT
with IA injuries that required intervention. (Table 3). Figures 1 and 2 demonstrate the total number and percentage of injuries as well as injuries requiring intervention that were detected with each RBC/hpf cutoff. For example, with a threshold value of 50-99 RBCs/hpf, 85% of GU
RI PT
injuries were identified and 100% of injuries that required intervention were identified.
The association between catheterization and false positive samples or severity of injury is also unknown in this patient population. Of those with documented samples, seventy patients
SC
had a catheterized sample; 50 of which (71%) had a positive result. One hundred and ten patients had clean catch samples; 89 of which (91%) had a positive result. There was no significant
M AN U
difference in number of positive samples between these two groups of patients (p = 0.64).
DISCUSSION
A urinalysis without any RBCs per high powered field after blunt abdominal trauma
TE D
correlates with a very low risk for an intra-abdominal or genitourinary injury. In our analysis, a negative urinalysis was associated with no genitourinary injuries that required surgery or IR intervention. Additionally, only two patients (0.2%) required intervention for an intra-abdominal
EP
injury after a negative urinalysis. The high sensitivity and negative predictive value of urinalysis make it an essential test for all blunt abdominal trauma patients to potentially avoid radiographic
AC C
imaging, and is included in the current blunt abdominal trauma workup at our institution. The use of routine CT scanning for blunt abdominal trauma has become more common,
but the high number of ‘negative’ scans has prompted the development of clinical prediction scores to identity patients who can be safely observed with serial exams and laboratory tests alone.13,14 Inclusion of microscopic hematuria on UA in these clinical prediction scores is inconsistent. The American College of Emergency Physicians (ACEP) currently recommends
7
ACCEPTED MANUSCRIPT
evaluation of urinalysis results to identify patient who may not need CT after blunt abdominal trauma. 14-17 In contrast, more recent studies have demonstrated that hematuria is not useful to identify injury and therefore urinalysis should not be routinely performed in blunt trauma
RI PT
patients.8,9
There is also discordance on the number of RBCs per high powered field (RBCS/hpf) that should be used as a cut-off to declare a UA positive. Based upon previous studies, 25-50
SC
RBCs/hpf is the most frequently used value to consider a UA positive.14-16 In our analysis, a threshold value was not evident and for the purposes of this study, the presence of any RBCs/hpf
M AN U
was considered positive. Moreover, our analysis suggests that this threshold may be more applicable to safely rule out injury, particularly in patients who are not undergoing further radiographic evaluation. For example, setting the threshold value at 50-99 RBCs/hpf would capture less than 75% of patient with GU injuries (Figure 1) and less than 70% of patients with
TE D
IA injuries (Figure 2).
A limitation of this review is its retrospective nature. Uniform performance of the UA in patients with blunt trauma was recommended but not prospectively enforced. A second major
EP
limitation is the type of specimen for urinalysis (clean catch vs. catheterized sample) was not consistent or regularly documented. Based on the limited number of results recorded, there was
AC C
no significant increase number of false positive in catheterized samples, but the total number of patients with specimen type documented was only 10% (180/1795 patients). Finally, the presence and severity of hematuria has been associated with abdominal injury if seen with other clinical signs and symptoms.18 In this study, symptoms at the time urinalysis samples were obtained were not reviewed.
8
ACCEPTED MANUSCRIPT
The urinalysis provides an excellent sensitivity for the presence of genitourinary and intra-abdominal injuries after blunt abdominal trauma. The presence of any RBCs in the urine sample should promote further evaluation. A negative urinalysis, however, nearly rules out intra-
RI PT
abdominal or genitourinary injury and should be evaluated prospectively as part of a clinical
AC C
EP
TE D
M AN U
SC
prediction score that seeks to avoid unnecessary radiation exposure from CT imaging.
9
ACCEPTED MANUSCRIPT
Table 1 – Injury Patterns by Urinalysis Result -UA (810 Patients)
p Values
GU Injuries
51
2
0.0001
GU Injuries Requiring Intervention
10
0
0.007
IA Injuries
174
32
0.0001
IA Injuries Requiring Intervention
48
2
0.0001
SC
RI PT
+ UA (985 Patients)
AC C
EP
TE D
M AN U
Table 1 legend: UA – urinalysis, GU – genitourinary, IA – intra-abdominal
10
ACCEPTED MANUSCRIPT
Table 2 - Diagnostic Characteristics of Urinalysis after Blunt Abdominal Trauma Any GU Injury
GU Injury Requiring Intervention
Any IA Injury
Sensitivity
0.98
1
0.85
0.96
Specificity
0.46
0.45
0.49
0.46
Positive Predictive Value
0.05
0.01
0.175
0.05
Negative Predictive Value
0.99
1
0.96
0.99
Positive Likelihood Ratio
1.83
1.82
Negative Likelihood Ratio
0.04
0
RI PT
SC 1.65
1.78
0.31
0.09
M AN U
AC C
EP
TE D
Table 2 legend: GU – genitourinary; IA – intra-abdominal
11
IA Injury Requiring Intervention
ACCEPTED MANUSCRIPT
GU Injuries
GU Injuries Requiring Intervention
IA Injuries
>1000 (33 patients)
21
8
24
13
500-1000 (14 patients)
4
0
8
1
100-499 (69 patients)
12
0
27
6
50-99 (120 patients)
14
0
40
11
10-49 (162 patients)
4
3
24
5
5-9 (106 patients)
0
0
11
3
1-4 (366 patients)
7
M AN U 0
AC C
EP
TE D
Table 3 legend: GU – genitourinary; IA – intra-abdominal
12
IA Injuries Requiring Intervention
RI PT
RBCs/hpf (n)
SC
Table 3 – Injury and Interventions Stratified by Urinalysis Results
41
9
ACCEPTED MANUSCRIPT
References:
AC C
EP
TE D
M AN U
SC
RI PT
1. Knudson MM, McAninch JW, Gomez R, Lee P, Stubbs HA. Hematuria as a Predictor of Abdominal Injury After Blunt Trauma. Am J of Surg 1992 Nov;164(5): 482-486 2. Grieshop NA, Jacobson LE, Gomez GA, Thompson CT, Solotkin KC. Selective use of computed tomography and diagnostic peritoneal lavage in blunt abdominal trauma. J Trauma 1995 May;38(5): 727-31 3. Brewer ME, Wilmoth RJ, Enderson BL, Daley BJ. Prospective comparison of microscopic and gross hematuria as predictors of bladder injury in blunt trauma. Urology 2007 Jun;69(6):1086-9. 4. Holmes JF, Sokolove PE, Brant WE, Palchak MJ, Vance CW, Owings JT, Kuppermann N. Identification of Children with Intra-Abdominal Injuries after Blunt Trauma. Ann of Emerg Med 2002 May; 39(5); 500-509. 5. Holmes JF, Mao A, Awasthi S, McGahan JP, Wisner DH, Kuppermann N. Validation of a Prediction Rule for Identification of Children with Intra-abdominal Injuries after Blunt Torso Trauma. Ann of Emerg Med 2009 Oct;54(4); 528-533. 6. Holmes JF, Wisner DH. McGahan JP, Mower WR, Kuppermann N. Clinical Prediction Rules for Identifying Adults at Very Low Risk for Intra-abdominal Injuries after Blunt Trauma. Ann Emerg Med. 2009: 54(4);575-584. 7. Poletti PA, Mirvis SE, Shanmuganathan K, Takada T, Killeen KL, Perlmutter D, Hahn J, Mermillod B. Blunt abdominal trauma patients: can organ injury be excluded without performing computed tomography? J Trauma 2004 Nov;57(5);1072-1081. 8. Deunk J, Brink M, Dekker HM, Kool DR, Blickman JG, van Vugt AB, Edwards MJ. Predictors for Selection of Patients for Abdominal CT After Blunt Trauma: A proposal for a Diagnostic Algorithm. Ann of Surgery 2010 Mar; 251(3); 512-520. 9. Olthof DC, Joosse P, van der Vlies CH, de Reijke TM, Goslings JC. Routine Urinalysis in Patients with a Blunt Abdominal Trauma Mechanism is Not Valuable to Detect Urogenital Injury. Emerg Med J 2015 Feb;32(2);119-23. 10. Caputo ND, Stahmer C, Lim G, Shah K. Whole –body computed tomographic scanning lead top better survival as opposed to selective scanning in trauma patients: a systematic review and metaanalysis. J Trauma Acute Care Surg 2014 Oct;77(4): 534-9. 11. Surendran A, Mori A, Varma DK, Fruen RL. Systematic Review of the benefits and harms of whole-body computed tomography in the early management of multitrauma patients: are we getting the whole picture? J Trauma Acute Care Suirg 2014 Apr;76(4):1122-30 12. Gordic S, Alkadhi H, Hodel S, simmen HP, Brueesch M, Frauemnfelder T, Wanner G, Sprengel K. Whole-body Ct-based imaging algorithm for multiple trauma patients: Radiation dose and time to diagnosis. Br J Radiol 2015 Mar;88(1047):20140616. 13. Jindal A, Velmahos GC, Rofougaran R. Computed Tomography for Evaluation of Mild to Moderate Pediatric Trauma, Are We Overusing It? World J Surg. 2002 Jan;26(1):13-16. 14. Holmes JF, McGahan JP, Wisner DH. Rate of Intra-abdominal Injury after a Normal Abdominal Computed Tomographic Scan in Adults with Blunt Trauma. Am J Emerg Med 2012 May;30(5):574-9. 15. Diercks DB, Mehrotra A, Nacarian DJ, Romes SB, Decker WW, Fesmire FM; American College of Emergency Physicians. Clinical policy:Critical Issues in the Evaluation of Adult Patients Presenting to the Emergency Department with Acute Blunt Abdominal Trauma. Ann Emerg Med 2001 Apr;57(4):387-404. 16. Richards JR, Derlet RW. Computed Tomography for Blunt Abdominal Trauma in the ED: A Prospective Study. Am J Emerg Med 1998;16(4);338-342.
13
ACCEPTED MANUSCRIPT
AC C
EP
TE D
M AN U
SC
RI PT
17. Corwin MT, Sheen L, Kuramoto A, Lamba R, Parthasarathy S, Holmes JF. Utilization of a Clinical Prediction Rule for Abdominal-Pelvic CT Scans in Patients with Blunt Abdominal Trauma. Emerg Radiol 2014 Dec; 21 (6):571-6. 18. Taylor GA, Eichelberger MR, Potter BM. Hematuria: A Marker of Abdominal Injury in Children after Blunt Trauma. Ann Surg 1988 Dec;208(6):688-93.
14
ACCEPTED MANUSCRIPT
M AN U
SC
RI PT
Figure 1: Percent of Patients with GU injury by RBCs/hpf Detected by RBCs/hpf Threshold Values
AC C
EP
TE D
GU = genitourinary RBCs/hpf = red blood cells per high-powered field.
ACCEPTED MANUSCRIPT
M AN U
SC
RI PT
Figure 2: Percent of Patients with IA Injury Detected by RBCs/hpf Threshold Values
AC C
EP
TE D
IA = intra-abdominal RBCs/hpf = red blood cells per high-powered field
S0002-9610(16)30285-9
DOI:
10.1016/j.amjsurg.2016.05.005
Reference:
AJS 11950
To appear in:
The American Journal of Surgery
Received Date: 27 February 2016 Revised Date:
28 April 2016
Accepted Date: 1 May 2016
Please cite this article as: Jones TS, Stovall RT, Jones EL, Knepper B, Pieracci FM, Fox CJ, Moore EE, Cothren Burlew C, A Negative Urinalysis is Associated with a Low Likelihood of Intra-abdominal Injury after Blunt Abdominal Trauma, The American Journal of Surgery (2016), doi: 10.1016/ j.amjsurg.2016.05.005. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
Teresa S. Jones MD
Edward L. Jones MD Bryan Knepper, BA
SC
Robert T. Stovall MD
RI PT
A Negative Urinalysis is Associated with a Low Likelihood of Intra-abdominal Injury after Blunt Abdominal Trauma
M AN U
Fredric M. Pieracci MD Charles J. Fox MD
Ernest E. Moore MD
TE D
Clay Cothren Burlew MD
EP
Presented at the 2015 Southwestern Surgical Congress Annual Meeting, Monterey CA.
AC C
From the Department of Surgery, Denver Health Medical Center and the University of Colorado School of Medicine, Denver CO
Address correspondence to:
Clay Cothren Burlew, MD FACS Director, Surgical Intensive Care Unit Program Director, SCC and TACS Fellowships Department of Surgery Denver Health Medical Center 777 Bannock Street, MC 0206 Denver, CO 80204 Phone: 303-602-1830 E-Mail: [email protected] 1
ACCEPTED MANUSCRIPT
Abstract Background: The utility of urinalysis to diagnose intra-abdominal (IA) or genitourinary (GU)
significance of urinalysis in the blunt trauma patient
RI PT
injury after blunt trauma remains controversial. The purpose of this study was to determine the
Methods: A retrospective review of patients admitted for blunt abdominal trauma from 2011-
SC
2013.
Results: 1795 patients sustained blunt abdominal trauma: mean age of 44±21 years; mean ISS of
M AN U
13 ±10. 810 patients had a negative urinalysis (45%). Two patients (2/810, 0.2%) had a GU injury and neither required intervention. Thirty-two patients (32/810, 4.0%) had an IA injury, and two (2/810, 0.02%) required intervention. The sensitivity for predicting GU injury requiring intervention was 1 and IA injury requiring intervention was 0.96. Negative predictive values
TE D
were 1 and 0.99
Conclusion: A negative urinalysis correlates with a low risk for GU and IA injury after blunt abdominal trauma. A negative urinalysis should be evaluated prospectively as part of a clinical
AC C
EP
prediction score to rule out injury and avoid unnecessary radiation exposure from CT imaging.
2
ACCEPTED MANUSCRIPT
Key words: urinalysis, hematuria, blunt abdominal trauma, blunt trauma, intra-abdominal,
RI PT
genitourinary
Summary for the Table of Contents
A urinalysis with no hematuria after blunt abdominal trauma is associated with low risk of intra-
SC
abdominal or genitourinary injuries that require intervention/treatment. Clinicians should
consider observation alone in patients with a negative urinalysis and no other indications for
M AN U
abdominal imaging after blunt abdominal trauma. A urinalysis can identify low risk patients, and
AC C
EP
TE D
thus should thus be obtained in all patients who suffer blunt abdominal trauma.
3
ACCEPTED MANUSCRIPT
The presence of hematuria in a trauma patient has been suggested as an indicator for genitourinary (GU) and intra-abdominal (IA) injury. While it is commonly accepted that gross hematuria is a marker for both GU and IA injuries, the significance of microscopic hematuria
RI PT
remains questionable.1-3 In children, a urinalysis with microscopic hematuria >5 RBCs per high powered field correlates with the presence of an IA injury.4,5 In the adult population, however, there is a discrepancy between hematuria and IA injury. A clinical prediction rule developed in
SC
2009 validated microscopic hematuria >25 RBCs per high powered field as predictive of blunt torso trauma in adults.6 In contrast, two studies demonstrated that even macroscopic hematuria
M AN U
was not accurate for predicting injury when utilized in adult patients who had concomitant CT scans.7,8 A more recent publication recommends omission of the urinalysis from routine trauma assessment.9
Suggestions that routine urinalysis can be omitted after blunt abdominal injury may stem
TE D
from the increased use of computed tomography in the evaluation of the trauma patient. Whole body CT scanning has been advocated to reduce morbidity and mortality in blunt trauma patients, however the increasing cost and radiation exposure remains a significant concern.10-12
EP
Identification of patients with a low risk of IA injury may help limit the number of CT scans that are obtained in trauma patients, and obtaining a urinalysis may aid in the identification of such a
AC C
patient cohort.
The purpose of this study was to define the utility of the urinalysis after blunt abdominal
trauma in a large patient population. We hypothesize that the urinalysis would identify a subset of patients who are low risk for GU and IA injury; this patient cohort could potentially be safely observed after blunt abdominal trauma without additional imaging.
4
ACCEPTED MANUSCRIPT
METHODS The Denver Health Medical Center (DHMC) Trauma Registry was queried for all blunt trauma patients between January 2011 and December 2013. DHMC is a state-cerified and
RI PT
American College of Surgeons-verified level I regional trauma center and an intergral teaching facility of the University of Colorado School of Medicine. Patients with a urinalysis within 12 hours of arrival to the emergency department were included in the study population. Patients
SC
with gross hematuria, an initial trauma workup at an outside facility, or no available urinalysis results were excluded. Patient demographics, mechanism of injury, Injury Severity Score (ISS),
M AN U
identified injuries, and need for intervention were recorded. The presence of any red blood cell or hemoglobin in the specimen was considered a positive urinalysis (UA). The sensitivity, specificity, positive and negative predictive values (PPV and NPV respectively) as well as likelihood ratio (LR) of the UA were calculated for all GU and IA
TE D
injuries and those GU and IA injuries that required intervention (surgical or an interventional radiology (IR) procedure). A p < 0.05 was considered statistically significant. The University of
RESULTS
EP
Colorado Multi-Institutional Review Board approved this study.
AC C
There were 3,932 patients evaluated for blunt trauma during the study period and 1,795
(46%) met inclusion criteria. The majority (1140 patients, 64%) were men with a mean age of 44±21 years of age and mean Injury Severity Score of 13±10. The most common mechanisms of injury were motor vehicle collisions in 628 patients (35%), followed by falls (487 patients, 27%), auto-vs-pedestrian collisions (214 patients, 12%) and assaults (171 patients, 10%). Two hundred and six patients (12%) had IA injuries including liver (92 patients, 45%), spleen (79 patients,
5
ACCEPTED MANUSCRIPT
38%) and kidney (45 patients, 22%). Fifty-three patients (24%) with IA injuries required intervention for their injuries: 50 patients went to surgery and three patients were treated with IR procedures. Of these IA injury patients, 10 patients had GU injuries requiring intervention (9
RI PT
patients went to surgery and 1 was treated by interventional radiology).
A negative urinalysis was documented in eight hundred and ten patients (45%). Of these patients, two (0.2%) had GU injuries and neither patient required intervention. There were thirty-
SC
two patients (4%) who had an IA injury and two patients (0.2%) required intervention. (Table 1) A positive urinalysis was documented in nine hundred and eighty five patients (55%). Of
M AN U
these patients, one hundred and seventy four (18%) had an IA injury and 51 patients (29%) required intervention. There were fifty-one patients (5%) who had GU injuries and 10 patients (22%) required intervention.
The sensitivity, specificity, positive and negative predictive values and likelihood ratios
TE D
of the UA after blunt abdominal trauma are reported in Table 2. The urinalysis has a high sensitivity and negative predictive value for IA (0.85 and 0.96 respectively) and GU (0.98 and 0.99 respectively) injuries. The urinalysis is even more sensitive and has a better NPV when it is
EP
used to identify only those patients who require intervention for their IA (0.96 and 0.99 respectively) or GU (1.0 and 1.0 respectively) injuries.
AC C
Patients with defined injuries were compared to the quantification of RBCs in the
urinalysis; this analysis was done to evaluate for a possible threshold RBC value for injury screening. Table 3 demonstrates the number of patients who had quantified microscopic hematuria and those who had injuries. For example, of the patients who had 1-4 red blood cells/high powered field, 7 had GU injuries and 41 had IA injuries. Having the threshold for a positive UA as 5-9 RBCs/hpf would have missed these injuries, which also included 9 patients
6
ACCEPTED MANUSCRIPT
with IA injuries that required intervention. (Table 3). Figures 1 and 2 demonstrate the total number and percentage of injuries as well as injuries requiring intervention that were detected with each RBC/hpf cutoff. For example, with a threshold value of 50-99 RBCs/hpf, 85% of GU
RI PT
injuries were identified and 100% of injuries that required intervention were identified.
The association between catheterization and false positive samples or severity of injury is also unknown in this patient population. Of those with documented samples, seventy patients
SC
had a catheterized sample; 50 of which (71%) had a positive result. One hundred and ten patients had clean catch samples; 89 of which (91%) had a positive result. There was no significant
M AN U
difference in number of positive samples between these two groups of patients (p = 0.64).
DISCUSSION
A urinalysis without any RBCs per high powered field after blunt abdominal trauma
TE D
correlates with a very low risk for an intra-abdominal or genitourinary injury. In our analysis, a negative urinalysis was associated with no genitourinary injuries that required surgery or IR intervention. Additionally, only two patients (0.2%) required intervention for an intra-abdominal
EP
injury after a negative urinalysis. The high sensitivity and negative predictive value of urinalysis make it an essential test for all blunt abdominal trauma patients to potentially avoid radiographic
AC C
imaging, and is included in the current blunt abdominal trauma workup at our institution. The use of routine CT scanning for blunt abdominal trauma has become more common,
but the high number of ‘negative’ scans has prompted the development of clinical prediction scores to identity patients who can be safely observed with serial exams and laboratory tests alone.13,14 Inclusion of microscopic hematuria on UA in these clinical prediction scores is inconsistent. The American College of Emergency Physicians (ACEP) currently recommends
7
ACCEPTED MANUSCRIPT
evaluation of urinalysis results to identify patient who may not need CT after blunt abdominal trauma. 14-17 In contrast, more recent studies have demonstrated that hematuria is not useful to identify injury and therefore urinalysis should not be routinely performed in blunt trauma
RI PT
patients.8,9
There is also discordance on the number of RBCs per high powered field (RBCS/hpf) that should be used as a cut-off to declare a UA positive. Based upon previous studies, 25-50
SC
RBCs/hpf is the most frequently used value to consider a UA positive.14-16 In our analysis, a threshold value was not evident and for the purposes of this study, the presence of any RBCs/hpf
M AN U
was considered positive. Moreover, our analysis suggests that this threshold may be more applicable to safely rule out injury, particularly in patients who are not undergoing further radiographic evaluation. For example, setting the threshold value at 50-99 RBCs/hpf would capture less than 75% of patient with GU injuries (Figure 1) and less than 70% of patients with
TE D
IA injuries (Figure 2).
A limitation of this review is its retrospective nature. Uniform performance of the UA in patients with blunt trauma was recommended but not prospectively enforced. A second major
EP
limitation is the type of specimen for urinalysis (clean catch vs. catheterized sample) was not consistent or regularly documented. Based on the limited number of results recorded, there was
AC C
no significant increase number of false positive in catheterized samples, but the total number of patients with specimen type documented was only 10% (180/1795 patients). Finally, the presence and severity of hematuria has been associated with abdominal injury if seen with other clinical signs and symptoms.18 In this study, symptoms at the time urinalysis samples were obtained were not reviewed.
8
ACCEPTED MANUSCRIPT
The urinalysis provides an excellent sensitivity for the presence of genitourinary and intra-abdominal injuries after blunt abdominal trauma. The presence of any RBCs in the urine sample should promote further evaluation. A negative urinalysis, however, nearly rules out intra-
RI PT
abdominal or genitourinary injury and should be evaluated prospectively as part of a clinical
AC C
EP
TE D
M AN U
SC
prediction score that seeks to avoid unnecessary radiation exposure from CT imaging.
9
ACCEPTED MANUSCRIPT
Table 1 – Injury Patterns by Urinalysis Result -UA (810 Patients)
p Values
GU Injuries
51
2
0.0001
GU Injuries Requiring Intervention
10
0
0.007
IA Injuries
174
32
0.0001
IA Injuries Requiring Intervention
48
2
0.0001
SC
RI PT
+ UA (985 Patients)
AC C
EP
TE D
M AN U
Table 1 legend: UA – urinalysis, GU – genitourinary, IA – intra-abdominal
10
ACCEPTED MANUSCRIPT
Table 2 - Diagnostic Characteristics of Urinalysis after Blunt Abdominal Trauma Any GU Injury
GU Injury Requiring Intervention
Any IA Injury
Sensitivity
0.98
1
0.85
0.96
Specificity
0.46
0.45
0.49
0.46
Positive Predictive Value
0.05
0.01
0.175
0.05
Negative Predictive Value
0.99
1
0.96
0.99
Positive Likelihood Ratio
1.83
1.82
Negative Likelihood Ratio
0.04
0
RI PT
SC 1.65
1.78
0.31
0.09
M AN U
AC C
EP
TE D
Table 2 legend: GU – genitourinary; IA – intra-abdominal
11
IA Injury Requiring Intervention
ACCEPTED MANUSCRIPT
GU Injuries
GU Injuries Requiring Intervention
IA Injuries
>1000 (33 patients)
21
8
24
13
500-1000 (14 patients)
4
0
8
1
100-499 (69 patients)
12
0
27
6
50-99 (120 patients)
14
0
40
11
10-49 (162 patients)
4
3
24
5
5-9 (106 patients)
0
0
11
3
1-4 (366 patients)
7
M AN U 0
AC C
EP
TE D
Table 3 legend: GU – genitourinary; IA – intra-abdominal
12
IA Injuries Requiring Intervention
RI PT
RBCs/hpf (n)
SC
Table 3 – Injury and Interventions Stratified by Urinalysis Results
41
9
ACCEPTED MANUSCRIPT
References:
AC C
EP
TE D
M AN U
SC
RI PT
1. Knudson MM, McAninch JW, Gomez R, Lee P, Stubbs HA. Hematuria as a Predictor of Abdominal Injury After Blunt Trauma. Am J of Surg 1992 Nov;164(5): 482-486 2. Grieshop NA, Jacobson LE, Gomez GA, Thompson CT, Solotkin KC. Selective use of computed tomography and diagnostic peritoneal lavage in blunt abdominal trauma. J Trauma 1995 May;38(5): 727-31 3. Brewer ME, Wilmoth RJ, Enderson BL, Daley BJ. Prospective comparison of microscopic and gross hematuria as predictors of bladder injury in blunt trauma. Urology 2007 Jun;69(6):1086-9. 4. Holmes JF, Sokolove PE, Brant WE, Palchak MJ, Vance CW, Owings JT, Kuppermann N. Identification of Children with Intra-Abdominal Injuries after Blunt Trauma. Ann of Emerg Med 2002 May; 39(5); 500-509. 5. Holmes JF, Mao A, Awasthi S, McGahan JP, Wisner DH, Kuppermann N. Validation of a Prediction Rule for Identification of Children with Intra-abdominal Injuries after Blunt Torso Trauma. Ann of Emerg Med 2009 Oct;54(4); 528-533. 6. Holmes JF, Wisner DH. McGahan JP, Mower WR, Kuppermann N. Clinical Prediction Rules for Identifying Adults at Very Low Risk for Intra-abdominal Injuries after Blunt Trauma. Ann Emerg Med. 2009: 54(4);575-584. 7. Poletti PA, Mirvis SE, Shanmuganathan K, Takada T, Killeen KL, Perlmutter D, Hahn J, Mermillod B. Blunt abdominal trauma patients: can organ injury be excluded without performing computed tomography? J Trauma 2004 Nov;57(5);1072-1081. 8. Deunk J, Brink M, Dekker HM, Kool DR, Blickman JG, van Vugt AB, Edwards MJ. Predictors for Selection of Patients for Abdominal CT After Blunt Trauma: A proposal for a Diagnostic Algorithm. Ann of Surgery 2010 Mar; 251(3); 512-520. 9. Olthof DC, Joosse P, van der Vlies CH, de Reijke TM, Goslings JC. Routine Urinalysis in Patients with a Blunt Abdominal Trauma Mechanism is Not Valuable to Detect Urogenital Injury. Emerg Med J 2015 Feb;32(2);119-23. 10. Caputo ND, Stahmer C, Lim G, Shah K. Whole –body computed tomographic scanning lead top better survival as opposed to selective scanning in trauma patients: a systematic review and metaanalysis. J Trauma Acute Care Surg 2014 Oct;77(4): 534-9. 11. Surendran A, Mori A, Varma DK, Fruen RL. Systematic Review of the benefits and harms of whole-body computed tomography in the early management of multitrauma patients: are we getting the whole picture? J Trauma Acute Care Suirg 2014 Apr;76(4):1122-30 12. Gordic S, Alkadhi H, Hodel S, simmen HP, Brueesch M, Frauemnfelder T, Wanner G, Sprengel K. Whole-body Ct-based imaging algorithm for multiple trauma patients: Radiation dose and time to diagnosis. Br J Radiol 2015 Mar;88(1047):20140616. 13. Jindal A, Velmahos GC, Rofougaran R. Computed Tomography for Evaluation of Mild to Moderate Pediatric Trauma, Are We Overusing It? World J Surg. 2002 Jan;26(1):13-16. 14. Holmes JF, McGahan JP, Wisner DH. Rate of Intra-abdominal Injury after a Normal Abdominal Computed Tomographic Scan in Adults with Blunt Trauma. Am J Emerg Med 2012 May;30(5):574-9. 15. Diercks DB, Mehrotra A, Nacarian DJ, Romes SB, Decker WW, Fesmire FM; American College of Emergency Physicians. Clinical policy:Critical Issues in the Evaluation of Adult Patients Presenting to the Emergency Department with Acute Blunt Abdominal Trauma. Ann Emerg Med 2001 Apr;57(4):387-404. 16. Richards JR, Derlet RW. Computed Tomography for Blunt Abdominal Trauma in the ED: A Prospective Study. Am J Emerg Med 1998;16(4);338-342.
13
ACCEPTED MANUSCRIPT
AC C
EP
TE D
M AN U
SC
RI PT
17. Corwin MT, Sheen L, Kuramoto A, Lamba R, Parthasarathy S, Holmes JF. Utilization of a Clinical Prediction Rule for Abdominal-Pelvic CT Scans in Patients with Blunt Abdominal Trauma. Emerg Radiol 2014 Dec; 21 (6):571-6. 18. Taylor GA, Eichelberger MR, Potter BM. Hematuria: A Marker of Abdominal Injury in Children after Blunt Trauma. Ann Surg 1988 Dec;208(6):688-93.
14
ACCEPTED MANUSCRIPT
M AN U
SC
RI PT
Figure 1: Percent of Patients with GU injury by RBCs/hpf Detected by RBCs/hpf Threshold Values
AC C
EP
TE D
GU = genitourinary RBCs/hpf = red blood cells per high-powered field.
ACCEPTED MANUSCRIPT
M AN U
SC
RI PT
Figure 2: Percent of Patients with IA Injury Detected by RBCs/hpf Threshold Values
AC C
EP
TE D
IA = intra-abdominal RBCs/hpf = red blood cells per high-powered field
