Adhesive small bowel obstruction is mechanical obstruction developing from postoperative peritoneal adhesions narrowing or kinking the small bowel, and is the most common cause of small bowel obstruction (60-75%). Prior abdominal surgery is the most important risk factor. On CT, dilated proximal small bowel loops (>3 cm), collapsed distal bowel, and a definite transition point are identified — the adhesive band is usually not directly visible at the transition point but its location is determined by inference. 'Small bowel feces sign' (fecal material appearance in small bowel) may be observed near the transition point, supporting obstruction localization. Strangulation (vascular compromise) findings: wall enhancement defect, mesenteric edema, 'whirl sign', and free fluid — these findings indicate surgical emergency.
Age Range
25-85
Peak Age
55
Gender
Equal
Prevalence
Common
Postoperative adhesions are a pathological result of the healing process based on fibrin deposition after peritoneal trauma (surgical manipulation, inflammation, ischemia). Normal peritoneal fibrinolysis mechanism (tPA) is suppressed by surgical trauma, and the fibrin matrix organizes into fibrous band structures. These bands connect small bowel loops to each other or peritoneal surfaces, causing kinking, compression, or internal herniation. At the obstruction point, bowel lumen narrows and fluid/gas accumulation with dilatation develops proximally — this 'transition point' is detected on CT as the clear boundary between dilated proximal and collapsed distal. 'Small bowel feces sign' results from intestinal content at the obstruction site taking fecal appearance due to prolonged stasis with partial absorption and bacterial fermentation — water absorption leaves concentrated particulate material creating mixed gas-particulate pattern on CT. Strangulation develops when the band compresses bowel wall or mesenteric vascular pedicle — venous return is first impeded (congestion, wall edema, mesenteric fluid), then arterial flow is compromised and transmural ischemia-necrosis begins. Wall enhancement defect reflects vascular perfusion loss of ischemic wall; 'whirl sign' reflects axial rotation of mesentery (volvulus).
Clear caliber change between dilated proximal and collapsed distal bowel (transition point) with fecal material-like intestinal content near the transition point — highly suggestive combination for adhesive small bowel obstruction.
On CT, a definite transition point between dilated proximal small bowel loops (>3 cm diameter) and collapsed distal bowel is identified. Bowel caliber changes abruptly at the transition point. Adhesive band is rarely directly visible — adhesive obstruction is diagnosed when no tumor, hernia, or other mechanical cause is present at the transition point.
Report Sentence
Transition point identified at [location] level in the small bowel with proximal segments dilated up to [value] cm and collapsed distal segments — consistent with adhesive obstruction.
Near the transition point, mixed gas-particulate content resembling fecal material is observed in the small bowel lumen. This finding supports obstruction localization and aids transition point identification.
Report Sentence
Small bowel feces sign is observed in the small bowel loop adjacent to the transition point, supporting obstruction localization.
In strangulation, the wall of the affected bowel segment shows no enhancement or markedly decreased enhancement. This finding reflects transmural ischemia and is the most reliable indicator of surgical emergency. Contrast difference forms with normally enhancing adjacent bowel segments.
Report Sentence
Wall enhancement defect in the [location] small bowel segment, consistent with strangulation/ischemia — EMERGENCY surgical consultation.
On axial CT, rotated, twisted appearance of mesenteric vessels and fat ('whirl sign') is observed. This finding suggests mesenteric torsion (volvulus) or internal herniation and indicates closed-loop obstruction with strangulation risk.
Report Sentence
Whirl sign in the [location] mesentery, consistent with mesenteric torsion and closed-loop obstruction — high strangulation risk.
In closed-loop obstruction, transition points form at both ends of a bowel segment, and the segment appears dilated in U or C shape. If both transition points converge at the same point, 'beak sign' forms. This pattern carries the highest strangulation risk.
Report Sentence
C/U-shaped isolated dilated segment in [location] small bowel with transition points at both ends, suggesting closed-loop obstruction — EMERGENCY surgical evaluation.
On non-contrast CT, dilated, fluid and gas-filled small bowel loops are observed. Fluid levels reflect obstruction duration. Wall density increase (>20 HU) suggests intramural hemorrhage or edema.
Report Sentence
[Number] small bowel loops dilated up to [value] cm with fluid-gas content on non-contrast CT, consistent with mechanical obstruction.
Criteria
Transition point present, no strangulation findings. Normal wall enhancement.
Distinct Features
Resolves with conservative treatment (nasogastric decompression + IV fluid) in 65-80%. Low surgical need.
Criteria
Vascular compromise findings: wall enhancement defect, mesenteric edema/fluid, pneumatosis.
Distinct Features
SURGICAL EMERGENCY. Mortality 25-30% with conservative treatment, 5-8% with early surgery.
Criteria
Obstruction points at both ends of bowel segment. U/C-shaped isolated dilated segment.
Distinct Features
Highest strangulation risk (70-80%). Whirl sign may accompany. Early surgical indication.
Distinguishing Feature
Hernia bowel segment passing through defect; in adhesive obstruction no hernia defect, adhesive band identified by inference
Distinguishing Feature
Tumor annular mass/wall thickening at transition point; in adhesive obstruction no mass at transition point
Distinguishing Feature
Intussusception target/sausage sign, telescoping bowel; adhesive obstruction caliber change at transition point
Distinguishing Feature
Crohn's segmental wall thickening, skip lesions, fistula/abscess; adhesive obstruction no inflammatory wall thickening at transition point
Urgency
emergentManagement
surgicalBiopsy
Not NeededFollow-up
no-follow-upConservative treatment (nasogastric decompression, IV fluid, nil per os) is first-line in simple adhesive obstruction — 65-80% success rate. If no improvement within 48-72 hours, surgery is evaluated. Strangulation or closed-loop findings are EMERGENCY surgical indications — delay leads to transmural necrosis and perforation. Surgery: laparoscopic or open adhesiolysis. Adhesion prevention strategies: minimally invasive surgery preference, anti-adhesion barriers, early mobilization. CT diagnoses obstruction with 90-95% sensitivity and 95-96% specificity and detects strangulation findings with high accuracy.
Adhesive small bowel obstruction requires either emergency surgery or conservative management. Strangulation signs (loss of wall enhancement, pneumatosis, portal venous gas) are emergency surgical indications. Surgical adhesiolysis is performed if resolution does not occur.