Sigmoid Volvulus

Sigmoid volvulus is axial twisting of a redundant sigmoid colon and its mesentery, producing large bowel obstruction with risk of vascular compromise, gangrene and perforation.

It is particularly important in Africa and other regions within the recognised volvulus belt. Predisposing factors include a long redundant sigmoid colon with narrow mesenteric base, chronic constipation and megacolon.

The critical initial distinction is uncomplicated viable volvulus versus ischaemic or perforated volvulus.

• Marked abdominal distension, colicky pain and absolute constipation are typical. Vomiting is often late.
• The abdomen may be dramatically distended while tenderness remains modest if bowel is viable.
• Severe continuous pain, focal or generalised peritonism, fever, haemodynamic instability or metabolic deterioration suggests gangrene or perforation.

Check renal function, electrolytes, blood count and lactate.

CT abdomen and pelvis: confirms twisted sigmoid mesentery and assesses viability and perforation.

Plain abdominal radiography may show the characteristic massively dilated inverted U or coffee bean configuration but cannot adequately determine bowel viability.

If there is no peritonitis, perforation or suspected bowel ischaemia, perform urgent flexible sigmoidoscopic or colonoscopic detorsion and decompression. The endoscopist should assess mucosal viability and pass beyond the torsion. Leave a rectal or decompression tube after successful detorsion where appropriate. WSES reports initial endoscopic success in approximately 60 to 95 percent of uncomplicated cases.

Do not attempt endoscopic detorsion when there is clear gangrene, perforation, diffuse peritonitis or septic shock.

Failed endoscopic detorsion or nonviable bowel requires urgent sigmoid resection. Ischaemic bowel should be resected with minimal unnecessary manipulation.

The choice after emergency resection is determined by physiology and contamination. A stable patient with viable bowel ends may undergo primary colorectal anastomosis. Severe sepsis, shock, acidosis, heavy contamination or poor tissue perfusion favours an end colostomy and rectal stump.

Successful endoscopic decompression is not definitive therapy. Recurrence after detorsion alone is high, commonly around 45 to 71 percent. Sigmoid colectomy should therefore be offered during the same admission or as early as feasible after stabilisation.

Nonresectional operations such as operative detorsion alone or sigmoidopexy have higher recurrence and are inferior to sigmoid colectomy.