Features on MDCT that predict surgery in patients with adhesive-related small bowel obstruction

Abstract

Purpose: The purpose of this study was to determine the contribution of multidetector-row computed tomography (MDCT) in the management of adhesion-related small bowel obstruction (SBO) and to identify its predictive value for surgery.

Methods: We conducted a retrospective review of 151 patients over a 5-year period with the diagnosis of SBO caused by adhesion. These patients were divided into two groups: surgery (n = 63) and observation group (n = 88). Two radiologists blinded to the outcome of the patients evaluated MDCT images retrospectively, recording the bowel diameter, bowel wall thickness, degree of obstruction, air-fluid level, mesenteric fatty stranding, transitional zone, intraperitoneal fluid, close loop, whirl sign, and faeces sign. Statistical analyses were performed using univariate and multivariable analyses.

Results: Multivariable analysis showed that MDCT demonstrated presence of intraperitoneal fluid (Odds ratio, OR, 4.38), high-grade or complete obstruction (OR, 3.19) and mesenteric fatty stranding (OR, 2.81), and absence of faeces sign (OR, 2.11) were the most significant predictors. When all of the four criteria were used in combination, high sensitivity of 98.4% and specificity of 90.9% were achieved for the prediction for surgery.

Conclusion: MDCT is useful to evaluate adhesion-related SBO and to predict accurately patients who require surgery. Use of the four MDCT features in combination is highly suggestive of the need for early surgical intervention.

Figure 1. Three degrees of SBO defined by MDCT images.

(a) “Low-grade partial” SBO. Note the moderate amount of gas and faeces in the ascending colon (arrows). (b) “ High-grade partial” SBO. Note the small amount of gas and fluid in the ascending colon (arrows). There is no evidence of small bowel wall thickening or ischemia. The maximal diameter of the obstructed fluid-filled small bowel (SB) is measured larger than 3.0 centimeter. (c) “Complete” SBO. Note the complete collapse of the ascending colon (arrows) with no appreciable gas or fluid.

Figure 2. Small bowel faeces sign.

Coronal MDCT image shows faeces-like material mixed with gas bubbles and fluid at the distal small bowel (SB). The finding is frequently seen proximal to the site of obstruction. Mesenteric fatty infiltration (arrows) and small amount of intraperitoneal fluid (asterisk) are also observed.

Figure 3. Closed-loop sign.

(a) Abdominal radiograph shows a C-shaped configuration of the bowel loops in the center of the abdomen, a finding that indicates closed-loop obstruction. (b) On coronal MDCT image, the affected loops (dotted line) are filled with gas. The stretched mesenteric vessels converging toward the site of torsion (arrow).

Figure 4. The “whirl” sign.

Axial MDCT image shows the whirl appearance of twisted mesenteric vessels (arrow), supplying the obstructed small bowel (SB) lying laterally to the colon.