Pediatr Radiol DOI 10.1007/s00247-014-3196-5

PICTORIAL ESSAY

Pitfalls in pediatric radiology Dawn R. Engelkemier & George A. Taylor

Received: 21 May 2014 / Revised: 20 September 2014 / Accepted: 25 September 2014 # Springer-Verlag Berlin Heidelberg 2014

Abstract This essay depicts some of the diagnostic errors identified in a large academic pediatric imaging department during a 13-year period. Our aim is to illustrate potential situations in which errors are more likely to occur and more likely to cause harm, and to share our difficult cases so other radiologists might learn without having to experience those situations themselves. Keywords Diagnostic errors . Heuristics . Pediatric . Radiology

7]. According to Larson [8], knowledge of errors can improve performance through feedback and learning. In that spirit, we present a series of diagnostic errors in imaging children, and discuss them within the context of perceptual/cognitive research associated with failures in perception, failed heuristics and biases [9, 10]. Suggestions are made for potential minimization of future errors based on available literature.

Identification and classification of errors Introduction Errors in clinical medicine have received a great deal of attention since the publication of the report entitled “To Err is Human” by the Institute of Medicine [1]. A great deal of literature exists on the types of errors encountered in adult radiology [2–5]. However, the disease entities encountered in pediatric radiology practice vary considerably from adult practice, and the types and causes of diagnostic errors in pediatric radiology have not been extensively studied [2–4, 6, D. R. Engelkemier (*) : G. A. Taylor Department of Radiology, Boston Children’s Hospital, Harvard Medical School, 300 Longwood Ave., Boston, MA 02115, USA e-mail: [email protected] D. R. Engelkemier Kern Radiology, 2301 Bahamas Dr., Bakersfield, CA 93309, USA

Between December 1998 and D ecember 2011, 168,400 cases were reviewed as part of our ongoing quality assurance process. This study was approved by our institution’s Internal Review Board and the requirement for informed consent was waived. Cases were identified using five general mechanisms of reporting: A hospital-wide sentinel event reporting system (SERS), radiologist double-read process, reports from weekly multidisciplinary conferences, reporting by individual radiologists identifying their own or other radiologists’ discrepancies, and daily review of trainee interpretations occurring after hours [3]. A total of 4,084 disagreements in diagnosis were identified. We limited our review to 484 cases that were initially classified as a disagreement in diagnosis that would have led to a minor change in therapy (Class III) or a disagreement in diagnosis that, if left uncorrected, would have led to a major change in therapy (Class IV) [3]. We defined a diagnostic error as a diagnosis that was delayed (sufficient information

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was available to make the diagnosis earlier), wrong (another diagnosis was made before the correct one) or missed (no diagnosis was ever made) [3, 11]. In all cases, the correct diagnosis was proved by clinical or imaging follow-up or by subsequent surgical or image-guided intervention. Most diagnostic errors are considered multifactorial in nature. However, for the educational purpose of this presentation, we characterized each error according to the most salient, primary error identified during a retrospective review. Errors were classified as primarily perceptual or primarily cognitive in order to better depict examples of each. Perceptual errors were defined as non-recognition of an imaging abnormality. Errors were defined as primarily cognitive in nature when they resulted from faulty information processing (overinterpretation of an imaging finding, misinterpretation of a finding or failure to consider a different diagnosis for a given finding [premature closure]), faulty data gathering (poorly performed imaging examination, inadequate review of patient history or lack of consideration of a patient’s underlying condition) or insufficient knowledge base [3, 11–13]. System-related errors were defined as technical (due to equipment failure) or organizational (ineffective policies, inadequate training or supervision, or defective communication). Repeated instances of the same error (clustering) were also included as a system-based error. An error was considered unavoidable when abnormal imaging findings were absent or masked, or findings were so atypical that arriving at a correct diagnosis would not be expected.

Fig. 1 Perceptual error: visual isolation. Lumbosacral spine radiograph from a scoliosis series in a 13-year-old girl shows physeal widening and posterior medial displacement of the right femoral head due to slipped capital femoral epiphysis (arrow). Finding was initially missed. Subsequent radiographs showed progressive displacement

Perceptual errors Although some findings may be quite subtle and difficult to readily identify, many of the errors we encountered were missed despite being visually obvious. These misses have been related to at least three visual phenomena: “satisfaction of search,” during which the detection of an abnormality satisfies the search for meaning and results in premature termination of further search; “visual isolation,” where attention is selectively focused on a main area of the image while little or no attention is given to secondary areas, and “visual distractors” in the form of overlying clutter or anatomical structures that simulate a pathological lesion [14–17] (Figs. 1, 2, 3, 4 and 5).

Fig. 2 Perceptual error: visual isolation. Coronal inversion recovery MR image in a 5-month-old boy with a left shoulder mass (not shown) shows multiple left posterior medial rib fractures (arrows). The rib fractures were unsuspected, only visualized on some sequences, and located near the edge of the images. Additional imaging showed multiple fractures of different ages, and multifocal intracranial hemorrhage, highly concerning for inflicted injury

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Fig. 3 Perceptual error: visual isolation. PA chest radiograph in a 3-yearold girl who swallowed a battery (a) shows the battery in the mid-thoracic esophagus. The rounded right paraspinal opacity (arrow) was missed on this study and on a subsequent upper GI performed after removal of the foreign body (b, arrow). Chest CT showed a right posterior mediastinal

soft tissue mass with calcifications, diagnosed as neuroblastoma. The contour of the mass mimics the right heart border on chest radiograph. The mass is only partially visualized and located at the edge of the upper GI image

Fig. 4 Perceptual error: satisfaction of search. Lateral hand radiograph in an 11-year-old girl with wrist pain after a fall shows a mildly angulated fracture through the distal radial metadiaphysis. The dorsal dislocation at the fifth digit proximal interphalangeal joint (arrow) was missed

Cognitive errors

Fig. 5 Perceptual error: distractor. AP pelvis radiograph in a 22year-old man with a history of hip impingement post right femoroacetabular osteochondroplasty shows a retained guidewire fragment from cannulated screw placement (arrow). The fragment was missed and migrated on subsequent radiographs. The guidewire fragment projects over the cannulated screws, which serve as distractors

Cognitive processes are complex and include a large number of mental shortcuts (known as heuristics) and biases potentially affecting clinical reasoning [9, 10, 18]. According to Croskerry [19], more than 75% of diagnostic failures in medicine are related to thinking failures. Rational, effortful thinking is estimated to account for less than 5% of overall cognition time [20]. The majority of thinking is intuitive and unconscious, which is efficient, but may be more prone to bias and error than rational thinking [21]. The numerous heuristics utilized by physicians to quickly arrive at diagnoses may result in diagnostic errors [22]. For purposes of this essay, we simplify the categorization of cognitive errors into those most commonly relating to information processing and faulty data gathering (Table 1, Figs. 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 and 17).

Pediatr Radiol Table 1 Categorization of cognitive errors Cognitive error Faulty information processing Faulty interpretation of test

Overinterpretation of test Premature closure Faulty context generation

Faulty knowledge Faulty data gathering (faulty or incomplete performance of test)

Definition

Diagnostic finding is correctly identified, but incorrect conclusion is drawn. Importance or relevance of diagnostic finding is overemphasized. Failure to consider other diagnostic possibilities. Lack of consideration of the clinical context of a patient’s situation relevant to the diagnosis. Insufficient knowledge of relevant condition. Failure to collect appropriate information prior to initiation of diagnostic test. Diagnostic test is conducted incorrectly or incompletely.

Table modified from Taylor et al. [3]

Fig. 7 Cognitive error: faulty interpretation of a test. Transverse sonographic image of the mid-pelvis in a 17-year-old girl with abdominal pain (a) shows two fluid-filled structures misinterpreted as urinary bladder (BLD) and free fluid (FF). Sagittal contrast-enhanced CT image (b) shows a large midline paraovarian cyst with the bladder compressed inferiorly (arrow) and the right ovary positioned superiorly (arrowhead). Repeat US confirmed the right paraovarian cyst and right ovarian torsion. The posterior fluid-filled structure demonstrates the typical contour of the urinary bladder wall while the anterior structure is more ovoid

System errors

Fig. 6 Cognitive error: marked physical deformity. Frontal radiograph of the lower chest and abdomen in a 12-year-old girl with marked thoracolumbar scoliosis shows an enteric tube to the right of the spine (arrow), interpreted to be in the distal esophagus. The tube was intrabronchial. Anatomical structures may be distorted in such a way that suboptimally implanted tubes or catheters may be perceived, but misinterpreted as being in correct location

Technical errors, equipment failures or errors in communication resulting in absent, confusing, incomplete or erroneous medical history are classified as system errors (Figs. 18 and 19).

Strategies for reduction of error Errors have been a part of diagnostic radiology since the beginning of our specialty. Due to the strong

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Fig. 9 Cognitive error: faulty interpretation of a test. Abdominal radiograph in a 13-year-old boy for feeding tube placement evaluation shows the tube tip superior to the right hemidiaphragm (arrow), but it was reported as not present. Chest radiograph revealed intrabronchial placement. The feeding tube was not in its expected location and interpreted as not present. The scattered oral contrast may have visually distracted from the small metallic density of the feeding tube tip

Fig. 8 Cognitive error: faulty interpretation of a test. Chest and abdomen radiograph in a newborn girl shows relative lucency of the liver interpreted as a large pneumoperitoneum. Findings were due to high attenuation ascites from intravenous contrast administration during a cardiac catheterization in the setting of renal failure. Observing the contrast in the collecting system and knowing the patient’s history may have prevented this error

effects of hindsight bias, simply looking at an error in retrospect and stating what should have been done to prevent the error is insufficient to prevent future errors from occurring. However, research in human factors suggests that human errors tend to occur in relatively predictable ways and with relatively predictable frequency [8, 23, 24]. A more effective approach focuses on improvement of the entire organization rather than individual poor performers, by identifying, sharing and learning from errors. Essential components of this approach include individual feedback, learning from others’ mistakes and focused education and training based on each error [8]. One strategy to minimize the recurrent satisfaction of search error uses checklists as aids to reduce

failure rates by promoting consistency and shifting mental tasks from subconscious to conscious [25, 26]. Self-prompting verbalization of the focus of attention has been shown to reduce this type of error [27]. Other strategies may seem obvious and self-evident, such as the routine use of window and level tools, review of prior imaging studies, and availability and review of appropriate patient history [3, 4, 28]. Yet, we have encountered frequent and recurrent failures in accomplishing these tasks during our ongoing peer review process. According to Larson and Nance [8], retrospective reviews of errors are important by themselves, but they do not lead to consistent exceptional performance. Identification and sharing of common errors in pediatric radiology is only the first step in a long path toward quality improvement. Rigorous, prospective performance improvement efforts are also required [8].

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Fig. 10 Cognitive error: premature closure. Transverse sonographic image of the scrotum with color Doppler in a 1-year-old boy with an enlarged testicle on physical exam (a) shows asymmetrical enlargement and hyperemia of the left testicle. The left epididymis showed similar changes. Sagittal sonographic image of the left scrotum (b) shows heterogeneity of the left testicle. Findings were interpreted as epididymo-orchitis. The discrete

Fig. 11 Cognitive error: premature closure. Sagittal proton density fat-saturated MR image of the left knee in a 9-year-old girl for evaluation of an osteochondral defect (a) shows a lobulated high signal intensity structure in the soft tissues superolateral to the knee joint thought to represent a benign cystic lesion (arrow). Sagittal post-contrast T1-weighted fat-saturated image from an MRI 3 months later for increased swelling (b) shows enlargement of the enhancing mass, a synovial sarcoma. Although, the lesion appeared cystic, no contrast was administered and so the possibility of a solid and potentially malignant lesion should not have been excluded initially. Earlier follow-up examination with US or contrast-enhanced MRI may have facilitated appropriate management

testicular mass (arrowheads) was not appreciated. Follow-up after antibiotic treatment showed enlargement of the mass, which was a yolk sac tumor. Although infection and inflammation are much more common causes for a hyperemic testicle and epididymis, other possible diagnoses must be considered, especially when the imaging and/or clinical scenario are atypical

Fig. 12 Cognitive error: faulty context generation. Sagittal sonographic image of the left kidney in a 7-month-old girl with hemihypertrophy shows prominent isoechoic tissue in the middle third of the kidney (arrow) thought to represent a column of Bertin. Follow-up US 2 months later showed enlargement of the region due to a Wilms tumor. The patient’s history of hemihypertrophy must be taken into account to generate appropriate concern over the otherwise benign appearing imaging finding

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Fig. 13 Cognitive error: failure to use all tools. Chest radiograph in a 16year-old girl post pectus excavatum repair with pectus bar in place (a) shows small bilateral pleural effusions and atelectasis. The small bilateral pneumothoraces are difficult to appreciate on the standard display

Fig. 14 Cognitive error: faulty/ incomplete test performance. Abdominal radiograph in a 4-dayold girl (a) shows the tip of an enteric tube in the distal esophagus and a paucity of bowel gas. Initial radiograph from an outside institution prior to the tube placement (b) shows marked gaseous distention of the stomach and duodenal bulb. Surgery confirmed duodenal stenosis with annular pancreas. The outside study was reportedly normal but not reviewed

window and were not reported. They are more clearly seen on the soft tissue window preset (arrows) (b). Using all available tools such as preset window settings may have prevented this error

Pediatr Radiol Fig. 15 Cognitive error: faulty/ incomplete test performance. Fluoroscopic image from a voiding cystourethrogram in a 4year-old boy (a) shows bilateral grade five vesicoureteral reflux with megacystis and megaureter. The child was unable to void during the study. Bilateral ureteral implantation was performed, but worsening hydroureteronephrosis developed. Repeat exam almost 3 years later (b) shows a dilated posterior urethra with posterior urethral valves (arrow). The initial incomplete exam resulted in delay in diagnosis and appropriate surgery

Fig. 16 Cognitive error: ineffective review of history. Chest radiograph in a 20-monthold boy with tracheoesophageal fistula and long gap esophageal atresia post repair (a) shows lucency along the superomedial mediastinum interpreted as a medial pneumothorax (arrowheads). Prior esophagram (b) shows a long stricture of the distal esophagus with dilatation of the proximal esophagus resulting in the lucency seen on the chest radiograph

Fig. 17 Cognitive error: inadequate knowledge base. Chest radiograph in a 5-year-old boy with double outlet right ventricle who had recently undergone pacemaker revision through a median sternotomy shows a wire mesh projecting over the right chest, which was thought to be external to the child. Surgical exploration confirmed a retained sponge behind the right anterior chest wall. Retained sponges are an uncommon finding, not previously encountered by the interpreting radiologist

Fig. 18 System error: technical error. Axial T1 post-contrast image from a surveillance MRI in a 30-month-old boy with bilateral Wilms tumor post treatment shows a small subcentimeter hypoenhancing mass (arrow) in the upper pole of the right kidney, which was missed. The lesion was only visible on one image in the sequence due to scanning parameters of 6-mm slice thickness and 5-mm gap. The mass was larger on subsequent abdominal MRI and was found to be recurrent Wilms tumor. The scanning parameters in this case were not adequate to identify a small tumor recurrence; a smaller slice thickness with minimal or no gap would have been more appropriate for this child

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Fig. 19 System error: technical error. Axial post-contrast CT (40 mA and 120 kVp) in a 10-year-old girl with multiple hepatic lesions on US (not shown) (a) shows several faintly perceptible low attenuation hepatic masses on liver window, which were not visible on soft tissue window.

Axial post-contrast CT (120 mA and 140 kVp) performed the next day displayed on liver window (b) clearly demonstrates the lesions, which were Burkitt lymphoma. Inappropriately low scanning parameters resulted in too much noise obscuring the salient finding

Conflicts of interest None

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