Other Bowel Issues

Question 1

Sigmoid volvulus

Answer 1

• Patients with longstanding chronic constipation tend to de­­velop a capacious, elongated and relatively atonic colon, especially in the sigmoid region.
• This is sometimes described as acquired or idiopathic megacolon.

Question 2

Pathophysiology of sigmoid volvulus

Answer 2

• Occasionally, a huge sigmoid loop, heavy with faeces and distended with gas, becomes twisted on its mesenteric pedicle (often abnormally narrow) to produce a closed-loop obstruction.
• If this volvulus is not corrected, venous infarction ensues, followed by perforation and catastrophic faecal peritonitis.
• This full picture is uncommon, but there is often a history of transient episodes of abdominal pain diagnosed as constipation.
• Note that volvulus elsewhere, of the caecum, small bowel or stomach is unrelated to constipation.

Question 3

Clinical features of sigmoid volvulus

Answer 3

• The patient with sigmoid volvulus is mildly unwell with abdominal distension and a variable degree of abdominal pain.
• There is absolute constipation (of both faeces and flatus) that has persisted for at least 24 hours. On digital examination, the rectum is empty but capacious. The abdomen is visibly distended and tympanitic to percussion but rarely tender.
• This is true even if the colon has reached the stage of venous infarction.
• Once perforation occurs, the full picture of faecal peritonitis will be evident.

Question 4

Management of sigmoid volvulus (1)

Answer 4

• Plain abdominal X-ray usually shows a single grossly dilated sigmoid loop, often reaching the xiphisternum.
• An erect film may reveal a characteristic ‘inverted U’ or ‘coffee-bean sign’ of bowel gas in the upper abdomen, with fluid levels at the same height in the two bowel limbs in the lower abdomen;
• a lateral decubitus X-ray may reveal two parallel fluid levels running the length of the abdomen.

Question 5

Management of sigmoid volvulus (2)

Answer 5

• A sigmoidoscope is gently passed as far as possible into the rectum and a flatus tube inserted through it.
• The end of the flatus tube is then gently manipulated through the twisted bowel into the obstructed loop.
• If this is successful, there is a gush of liquid faeces and flatus, relieving the obstruction.
• tube can be left in situ for 24 hours to maintain decompression, discourage re-twisting and allow recovery

Question 6

Sigmoid volvulus surgery

Answer 6

• sigmoid colectomy is usually required to prevent recurrence
• A safe alternative procedure is to excise the sigmoid and bring the divided ends of bowel out to form a double-barrelled colostomy
• For recurrent volvulus, sigmoid colectomy or suturing the bowel to the abdominal wall to prevent twisting may be performed electively