Bowel obstruction — closed-loop and volvulus

Closed-loop. Segment occluded at both ends (e.g. volvulus, some hernias, adhesive bands). Pressure rises rapidly; venous then arterial failure; strangulation within hours. Plain film may look deceptively mild — CT is definitive.^[1]

CT ischaemia signs. Wall thickening, mesenteric oedema/engorgement, reduced/absent wall enhancement, pneumatosis, portal venous gas, ascites, swirl/whirl of mesentery in volvulus.^[3]

Adhesive SBO without ischaemia. NBM, NG, IV saline+K, serial exams, possible gastrografin challenge; operate if failure/strangulation signs.^[1]

Sigmoid volvulus. Coffee-bean appearance; if no peritonism/ischaemia → endoscopic decompression then semi-elective definitive surgery; if ischaemic/peritonitic → emergency resection (often Hartmann). Caecal volvulus more often needs early surgery because endoscopic success is poor.^[1]