CT proves its worth for investigating bowel obstruction

Two and a half years worth of data suggest that CT is the most accurate, cost-effective imaging modality for diagnosing the causes of large bowel obstruction, according to investigators in the U.K.

CT scanning has taken hold as the established imaging modality for the diagnosis of patients with suspected small bowel obstruction. When it comes to large bowel obstruction, however, barium enema and contrast-enhanced fluoroscopy remain the standard of care.

Large bowel obstruction can be difficult to pin down with conventional imaging. Some techniques could be too invasive for frail patients, since the condition usually occurs as a byproduct of cancer, gallstones, hernias, and other painful, debilitating gastrointestinal conditions.

CT can address this problem, according to principal investigator Dr. Sathi Sukumar, a consultant radiologist at the University Hospital of South Manchester.

"Previously, and even now, contrast enema is used, and this can be highly unpleasant in this group of patients," Sukumar said.

CT can be performed with no bowel preparation. The patient can be transported straight from the emergency room to generate a rapid diagnosis, he said.

Sukumar and colleagues retrospectively reviewed 2400 CT reports on inpatient cases of suspected large bowel obstruction, large bowel dilatation, or pseudo-obstruction spanning 30 months of clinical practice. They identified 42 on whom clinical, endoscopic, and surgical follow-up data were available.

The investigators found that CT was highly sensitive and specific in identifying the causes of dilated large bowel loops in these patients. They released their findings at the 2008 American Roentgen Ray Society meeting.

Of these 42 cases, CT identified 31 as mechanical large bowel obstructions and eight as pseudo-obstructions. CT was unable to determine the causes of three cases of large bowel obstruction, two of which were later confirmed as carcinomas.

The most frequent causes of large bowel obstruction were carcinomas, volvulus, diverticular strictures, hernias, inflammatory strictures, and gallstone obstructions. Sensitivity and specificity of CT diagnoses of large bowel obstructions were, respectively, 94% and 100%.

"The results of this study could simplify the diagnostic process dramatically. A large number of patients in our study were frail or unwell, so it is particularly important in this group that diagnosis is achieved with the least invasive and quickest method possible," Sukumar said.

CT can help referring physicians confirm or rule out large bowel obstruction as well as provide important information for management, such as impending perforation. Early intervention in these patients could reduce morbidity and even save lives. Findings also suggest that fewer patients may need to undergo unpleasant contrast enemas, said coauthor Sam Byott, who presented the study.

Radiologists will see their lives become easier as well, Byott said. Fast CT scanning and image reconstruction will help busy radiologists as well as trainees get more accurate reporting.

"The straightforward nature of the test and the one-test diagnosis strategy will eventually save time and resources for the hospital trust," he said.

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