Sigmoid Volvulus

General Considerations

• Twisting of loop of intestine around its mesenteric attachment site may occur at various sites in the GI tract
• Most commonly: sigmoid & cecum
• Rarely: stomach, small intestine, transverse colon
• Results in partial or complete obstruction
• May also compromise bowel circulation resulting in ischemia
• Sigmoid volvulus most common form of GI tract volvulus
• Accounts for up to 8% of all intestinal obstructions
• Most common in elderly persons (often neurologically impaired)
• Patients almost always have a history of chronic constipation

Pathophysiology

• Redundant sigmoid colon that has a narrow mesenteric attachment to posterior abdominal wall allows close approximation of 2 limbs of sigmoid colon à twisting of sigmoid colon around mesenteric axis
• Other predisposing factors
  • Chronic constipation
  • High-roughage diet (may cause a long, redundant sigmoid colon)
  • Roundworm infestation
  • Megacolon (often due to Chagas dz)
• 20-25% mortality rate
• Peak age > 50 yrs.
• Second largest group à children
• Torsion usually counterclockwise ranging from 180 – 540 degrees
• Luminal obstruction generally @ 180 degrees
• Venous occlusion generally @ 360 degrees à gangrene & perforation
• Signs and symptoms
• May present as abdominal emergency
• Acute distension
• Colicky pain (often LLQ)
• Failure to pass flatus or stool (constipation is prevailing feature)
• Vomiting is late sign
• Distention may compromise respiratory & cardiac function
• May also present with surprisingly few signs and symptoms in bedridden and debilitated
• Physical examination
• Tympanitic abdomen
• Abdominal distention
• +/- palpable mass

Diagnosis

• Abdominal plain films usually diagnostic
  • Inverted U-shaped appearance of distended sigmoid loop
    • Largest  and most dilated loops of bowel are seen with volvulus
  • Loss of haustra
  • Coffee-bean sign à midline crease corresponding to mesenteric root in a greatly distended sigmoid
    • Sigmoid volvulus – bowel loop points to RUQ
    • Cecal volvulus – bowel loop points to LUQ
      • Dilated cecum comes to rest in left upper quadrant
  • Bird’s-beak or bird-of-prey sign à seen on barium enema as it encounters the volvulated loop
• CT scan useful in assessing mural wall ischemia

Differential Diagnosis

• Large bowel obstruction due to other causes à sigmoid colon CA
• Giant sigmoid diverticulum
• Pseudo-obstruction
• Colonic ischemia
• Perforation
• Sepsis

Treatment

• Laparoscopic de-rotation or laparotomy +/- bowel resection
• De-rotation & decompression by barium enema or with rectal tube, colonoscope, or sigmoidoscope if no signs of bowel ischemia or perforation
• Cecopexy à suture fixation of bowel to parietal peritoneum may prevent recurrence
• Recurrence rate after decompression alone à 50%

Sigmoid Volvulus. Dilated loop of sigmoid colon has a "coffee-bean" shape and
the wall between the two volvulated loops of sigmoid (black arrow) "points" towards the right upper quadrant. There is a considerable amount of stool in the colon from chronic constipation.
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Sigmoid Volvulus. Photo on left shows large, dilated loop of large bowel with an inverted U-shape
with walls between two volvulated loops pointing from LLQ toward RUQ;
Photo on right shows same patient with decompressed sigmoid volvulus following insertion of rectal tube