[Closed loop intestinal obstruction: role of computerized tomography]

The obstruction of a bowel segment at both ends results in a closed loop obstruction. Progression to strangulation frequently occurs if surgical intervention is delayed. The role of plain radiography in the diagnosis of closed loop obstruction and strangulation has been shown to be limited, while the recent literature has demonstrated the growing role of computed tomography (CT). This paper reports our experience in the study of closed loop obstruction by CT.

The CT studies of 12 patients with surgically confirmed closed loop obstruction were retrospectively reviewed. The following CT signs were used for the diagnosis: a) fluid-filled distended loops, b) C-shaped incarcerated loop, c) radial distribution of several dilated bowel loops and mesenteric vessels converging toward the point of obstruction, d) triangular or fusiform tapering of the closed loop and/or whirl sign in the site of obstruction.

On the basis of these signs, the diagnosis was made in 11 of 12 patients. Only 1 patient, who had a negative CT study, was positive at a subsequent enteroclysis. CT findings of strangulation were associated in 3 cases: slight wall thickening with vascular congestion and mesenteric ascites, confirmed at surgery.

Small bowel obstruction can be distinguished into simple and closed loop obstructions. The latter is a more severe condition which is often complicated by strangulation with vascular impairment, edema and intramural and mesenteric hemorrhage. Consequent arterial insufficiency rapidly leads to ischemia, infarction and necrosis. The radiologist plays a role in the early recognition of the closed loop obstruction and of any sign of strangulation. The role of CT in the diagnosis and workup of patients with suspected intestinal occlusion has been analyzed in the literature with reported 63% sensitivity, 78% specificity and 66% accuracy. CT is also capable of revealing the causes of occlusion in 73-95% of cases. The above CT signs, as confirmed in our experience, allow to identify closed loop obstruction and also small bowel strangulation, thus supplying a valuable contribution to diagnosis and accurate preoperative evaluation. We conclude that CT can accurately demonstrate the presence of closed loop obstruction and can be the technique of choice in patients in whom obstruction is associated with clinical signs suggestive of strangulation.