Sigmoid volvulus

Sigmoid volvulus

Description, Causes and Risk Factors:

Sigmoid volvulus occurs when the last part of the large bowel just before the rectum (the sigmoid shaped sigmoid colon) twists on its self. In the US sigmoid volvulus accounts for < 10% of intestinal obstruction cases. In Bolivian and Peruvian Andes, sigmoid volvulus accounts for 80% of obstruction cases. In US and Western Europe, sigmoid volvulus is associated with chronic constipation and laxative abuse. In developing countries, sigmoid volvulus is associated with diets high in vegetable fiber.

In the US, a long, redundant sigmoid colon - commonly seen in patients with illnesses such as Parkinson's disease (PD), multiple sclerosis (MS), spinal cord injuries, and psychiatric disorders - is the major cause of sigmoid volvulus. Inhibition of colonic motility by psychotropic medications as well as the possible inherent colonic dysmotility properties of the primary disease leads to sigmoid elongation. This redundant, enlarged bowel cause the approximation of 2 limbs of sigmoid colon and predisposes the limbs to twist around the mesenteric axis. Similarly, the patient with congenitally narrow sigmoid mesentery is predisposed to sigmoid volvulus due to increased mobility of the colon. Hirschsprung's disease affects the myenteric plexus of the colon also predisposes the patient to sigmoid volvulus.

Chronic constipation most often resulting from the low physical activity levels seen in resident of nursing care facilities, is also a cause of sigmoid volvulus secondary to sigmoid enlargement. Another important etiologic factor is the repetitive use of laxatives, cathartic agents, and enemas. The etiology of sigmoid volvulus in younger patients has been thought to be a congenital megasigmoid with additional stimuli such as purgation, diet, fecal loading, active peristalsis, or pregnancy.

Outside US, sigmoid volvulus may be caused by diet or infectious etiologies. Patients in non-industrialized countries often have high-residue diets that may results in overloading and enlargement of the sigmoid colon, prompting rotation around the root of the mesentery. The myenteric plexus of the bowel is affected by Chagas' disease, resulting in megacolon and predisposing the patient to sigmoid volvulus. Roundworm infestation is prevalent in more than 1 million people worldwide and causes sigmoid enlargement secondary to constipation.

Risk factors:

    The elderly (it is most common in those aged over 50 years but the next most commonly affected group is children).

  • Chronic constipation.

  • Megacolon, large redundant sigmoid colon and excessively mobile colon.

  • It is more common in men.

Prevention of volvulus is basically a matter of preventing chronic constipation. A diet too high in high fibre diet would lead to elongation of the bowel, and large redundant sigmoid or mega colon.


Signs and symptoms may include:

    Abrupt onset of severe, continuous crampy abdominal pain with colicky component due to peristalsis.

  • Constipation versus absence of stools versus absence of flatus.

  • Nausea plus vomiting with consequent dehydration.

  • Abdominal tenderness with tympanitic distension.

  • Peritoneal signs, fever, tachycardia ischemia or infarction, 7% of patient present with gangrene.

  • Young patients may have recurrent attacks due to spontaneous torsion and detorsion.


Differential diagnosis (DDx) may include:

    Colorectal carcinoma.

  • Diverticular disease with sigmoid formation.

  • Intussusception.

  • Ogilvie syndrome.

  • Distal small bowel obstruction.

Doctors may wish to do a combination of the following investigations to confirm the presence of a sigmoid volvulus:

    X-ray: A normal plain abdominal x-ray will demonstrate a huge air filled distended bowel like the shape of an inverted U, with the convexity of the U facing the right upper abdominal quadrant. This shape has been described as the kidney bean shape, coffee bean shape, bent inner tube shape, ace of spades or `Omega loop Sign'.

  • Barium Enema: With a water soluble barium enema, the dilatation in the sigmoid colon can be demonstrated to be due to a twist, as it will show an area of complete obstruction with some twisting in the so called bird beak or bird of prey sign.

  • Colonoscopy could be done in rare cases, which would help to confirm diagnosis, as well as treating the obstruction.


Urgent hospital admission and treatment are required. Acute sigmoid volvulus is a surgical emergency. Any delay in treatment increases the risk of bowel ischemia, perforation, and fecal peritonitis.

If strangulation is not suspected:

    Rigid sigmoidoscopy reduces the volvulus 85-95% of time. Advance to 25-30 cm. Successful if meet a gush of air/stool. Use colonoscopy if volvulus beyond length of rigid scope. Flexible sigmoidoscope is not as good.

  • Rectal tube placed beyond area of torsion (48-72 hrs) until bowel function resumes prevents immediate recurrence.

  • Elective sigmoid resection with primary anastomoses to prevent recurrence which is 50-90% in hours to weeks. Do a bowel prep. Recurrence after sigmoid resection is less than 3%.

  • If rigid sigmoidoscopy fails: Operative reduction. Unless necrosis is found, do not remove unprepped bowel due to increase risk of anastomotic leak. If necrosis is found on sigmoidoscopy then stop to prevent perforation. Perform Hartmann's procedure (sigmoid resection with end-descending colostomy and stapling of the rectal stump). Do reanastomosis later with bowel prep. If patient cannot tolerate elective resection then case reports of endoscopic sigmoidopexy (fix sigmoid to abdominal wall).

If strangulation is suspected (mortality of 30-60%): Do not use sigmoidoscope since perforation may occur. Perform lower anterior resection to remove affected segment.

NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.

DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.


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