COMPUTED-TOMOGRAPHY COMPARED WITH SMALL-BOWEL ENEMA IN CLINICALLY EQUIVOCAL INTESTINAL-OBSTRUCTION

Objective: To compare the findings in computed tomography (CT) and sma ll bowel enema (SBE) in clinically equivocal small bowel obstruction i n order to identify the reasons for the limitation of CT evaluation. S ubject and Method: Over a period of 5 years, 49 patients who had both CT and SBE within a period of 1 week were analysed. The findings at SB E were categorized into partial low-grade, partial high-grade and comp lete obstruction and compared with the CT findings. A critical analysi s of the CT false-negative cases was made, The predictive values for t he determination of the presence of obstruction in CT were also obtain ed. Results: Forty-three out of the 49 patients had proven intestinal obstruction. CT correctly identified 34 cases including 19 of 20 with partial high-grade obstruction, two with complete obstruction and 13 o ut of 21 cases of partial low-grade obstruction. Among those cases wit h low-grade obstruction cases with complex or long segment narrowing o r with masses were correctly identified while six patients with short stenotic segment due to various causes were not, CT also had two false -positive findings of obstruction in patients with mesenteric infarcti on, SBE had neither false positive nor false negative. The sensitivity , specificity, positive predictive value and negative predictive value s for CT were 83%, 67%, 94% and 36%, respectively. Abrupt transition f rom dilated to collapsed loops in CT were caused by various intralumin al lesions apart from adhesions, CT was superior to SBE in showing ext raluminal masses, revealing abscesses, tuberculous lesions and maligna ncy anterior adhesions as well as features of strangulation. Conclusio n: Apart from degree of obstruction and the presence of masses, the le ngth of the stenotic part also affected CT detection, Abrupt change fr om dilated to collapsed segment could be due to various transmural and intraluminal lesions although adhesions was the commonest lesion, Whi le SBE is more accurate in identifying the presence and location of ob struction, CT is superior for detection of the cause of small bowel ob struction and also for the presence of strangulation, In places where CT is more widely used for intestinal obstruction, SBE evaluation coul d be prudently considered in CT negative cases of clinically equivocal intestinal obstruction.