BLUNT BOWEL AND MESENTERIC INJURIES: THE ROLE OF SCREENING COMPUTED TOMOGRAPHY.

Malhotra AK, et al. J Trauma 2000 Jun;48(6):991-8; discussion 998-1000.

BACKGROUND: Early generation scanners have demonstrated poor sensitivity detecting blunt bowel/mesenteric injuries (BBMI). This study was aimed at determining the accuracy and role of helical scanners in BBMI.

METHODS: Retrospective chart review of patients with BBMI, or computed tomographic scans suspicious of BBMI, from August of 1995 to December of 1998.

RESULTS: One hundred of 8,112 scans (1.2%) were suspicious of BBMI. Of these suspicious scans, 53 patients had BBMI (true positive-TP) and 47 patients did not (false positive-FP). Seven patients with negative scans had BBMI (false negative-FN). Computed tomography contributed toward early surgery in 77% of patients who may have been delayed. Six patients developed intra-abdominal abscess. The abscess group had a significantly longer time interval from injury to surgery. Multiple findings were seen in 57% of true positive scans, whereas in 13% of false positive scans (p < 0.0001). An algorithm for management of BBMI is presented.

CONCLUSION: Helical scanners have high accuracy in detecting BBMI. Single versus multiple findings are useful in managing these injuries.

HELICAL COMPUTED TOMOGRAPHY OF BOWEL AND MESENTERIC INJURIES.

Killeen KL, et al. J Trauma 2001 Jul;51(1):26-36.

BACKGROUND: The role of computed tomography in diagnosing hollow viscus injury after blunt abdominal trauma remains controversial, with previous studies reporting both high accuracy and poor results. This study was performed to determine the diagnostic accuracy of helical computed tomography in detecting bowel and mesenteric injuries after blunt abdominal trauma in a large cohort of patients.

METHODS: One hundred fifty patients were admitted to our Level I trauma center over a 4-year period with computed tomographic (CT) scan or surgical diagnosis of bowel or mesenteric injury. CT scan findings were retrospectively graded as negative, nonsurgical, or surgical bowel or mesenteric injury. The CT scan diagnosis was then compared with surgical findings, which were also graded as negative, nonsurgical, or surgical.

RESULTS: Computed tomography had an overall sensitivity of 94% in detecting bowel injury and 96% in detecting mesenteric injury. Surgical bowel cases were correctly differentiated in 64 of 74 cases (86%), and surgical mesenteric cases were correctly differentiated from nonsurgical in 57 of 76 cases (75%).

CONCLUSION: Helical CT scanning is very accurate in detecting bowel and mesenteric injuries, as well as in determining the need for surgical exploration in bowel injuries. However, it is less accurate in predicting the need for surgical exploration in mesenteric injuries alone.

PERFORMANCE OF CT IN DETECTION OF BOWEL INJURY.

Butela ST, et al. AJR Am J Roentgenol 2001 Jan;176(1):129-35.

OBJECTIVE. The objective of our study was to identify relevant and reliable CT signs of bowel injury, to determine the overall performance of CT in detection of bowel injuries, and to establish the effect of the training level of radiologists on this performance.

MATERIALS AND METHODS. Abdominal CT scans of 112 patients with blunt abdominal trauma were prospectively and retrospectively reviewed. Fifty patients had proven bowel injuries (with or without other visceral injuries), whereas 62 patients had no bowel injury and comprised the comparison or control group. Thirty-one of the 62 patients in the comparison group had surgical proof of abdominal but not bowel or mesenteric injuries. The retrospective review of the 112 CT scans was performed randomly and individually by nine radiologists unaware of the diagnosis, including three faculty abdominal radiologists, three senior residents in training, and three junior residents in training. Individual performance and group performance were evaluated by receiver operating characteristic analysis, and interobserver agreement was tested. Individual CT signs as relevant predictors of bowel injury were identified by logistic regression.

RESULTS. Relevant predictors of bowel injury included mesenteric infiltration, bowel wall thickening, extravasation of vascular or enteric contrast agent, and the presence free air. In the retrospective blinded review, CT showed good to excellent interobserver reliability for individual CT signs as well as for diagnosis of bowel and visceral injuries. Faculty radiologists tended to diagnose injuries with greater accuracy and confidence, but they showed significantly better performance than residents only in diagnosing duodenal perforation. For the prospective CT diagnosis of bowel injury, CT had a sensitivity of 64%, an accuracy of 82%, and a specificity of 97%.

CONCLUSION. Bowel injuries are challenging to diagnose on CT. Radiologists with various levels of experience and expertise can achieve accurate and reproducible results using a variety of CT criteria.

COMMENTS: CT represents an excellent tool in evaluating blunt abdominal trauma. However, it is still prudent to get surgical consultation in those patients with “negative” CT, but a high suspicion of bowel injury, eg. extreme pain, unable to tolerate PO.