Sigmoid Volvulus

Occurs in cases of long standing chronic constipation where patients develop a large, elongated, relatively atonic colon particularly in the sigmoid segment. Often referred to as acquired or idiopathic megacolon. In sigmoid volvulus a large sigmoid loop full of faeces and distended with gas twists on its mesenteric pedicle to create a closed-loop obstruction. If uncorrected, venous infarction leads to perforation and faecal peritonitis.

• Uncommon although there may be under-diagnosed cases of incomplete volvulus.
• However the sigmoid colon is the most common part of the gastrointestinal tract to be affected by volvulus and accounts for up to 10% of all cases of intestinal obstruction.
• Sigmoid volvulus is more common in developing parts of the world with diets very high in fibre.

Risk factors

• Elderly (most common in those aged over 50 years but next most common affected group is children)
• Chronic constipation
• Megacolon, large redundant sigmoid colon and excessively mobile colon
• More common in men

• Most often presents with sudden onset colicky lower abdominal pain associated with gross abdominal distension and a failure to pass either flatus or stool.
• May present insidiously with chronic abdominal distension, constipation, vague and usually colicky lower abdominal discomfort and vomiting.
• May be a history of recurrent mild attacks relieved by passage of large amounts of stool and/or flatus.
• Vomiting occurs late, when the distension may be very severe.
• Abdominal examination reveals a tympanitic, distended (but usually non-tender) abdomen, and a palpable mass may be present.
• Shock and an elevation of temperature may be present if colonic perforation has occurred.
• Rectal examination shows only an empty rectal ampulla.
• Delay in diagnosis and treatment results in colonic ischaemia with features of perforation and peritonitis.

• Plain abdominal X-ray: single grossly dilated sigmoid loop commonly reaching the xiphisternum.
• May need limited barium enema without bowel preparation (can result in decompression itself).
• CT scanning is the least invasive imaging technique that allows assessment of bowel wall ischaemia.¹

• Other forms of large-bowel obstruction, especially carcinoma of the sigmoid colon
• Pseudo-obstruction (reduced colonic motility and dilatation)
• Giant sigmoid diverticulum
• Severe constipation

Urgent hospital admission and treatment. Any delay in treatment increases the risk of bowel ischaemia, perforation and faecal peritonitis.

• Decompression:
  • With the patient in the left lateral position, decompression and untwisting of the sigmoid loop may be achieved by passing a sigmoidoscope gently into the rectum as far as possible and a flatus tube passed alongside the sigmoidoscope. This is then gently manoeuvred into the obstructed loop through the twisted bowel producing a rush of liquid faeces and flatus with relief of the obstruction.
  • This procedure allows for rapid decompression of the distended colon, with the immediate relief of symptoms. Tube is left in place for 24 hours to maintain decompression, prevent recurrence and give time for vascular supply to bowel wall to recover.²
  • The patient should be observed for persistent abdominal pain and bloodstained stools, which may indicate ischaemia and the need for surgical intervention.
• Surgery:
  • Usually double-barrelled colostomy where both divided ends of bowel are brought out on to the abdominal wall (Paul-Mickulicz procedure).
  • Is indicated for patients in whom tube decompression fails or for those who have signs suggesting bowel ischaemia.
  • After conservative treatment, further episodes of volvulus occur in approximately 60% of patients and elective surgery is then frequently required to prevent further recurrence.
  • When condition recurs after non-surgical decompression, elective sigmoid colectomy or suturing of bowel to abdominal wall to prevent twisting.³

• Reported mortality rates are as high as 20-25%, depending on the interval between diagnosis and treatment.¹