A 68-year-old female patient came to our hospital with generalised abdominal pain and abdominal distension. The patient was haemodynamically stable.
Scanogram (Fig. 1) shows dilated bowel loops with classic inverted U configuration, "coffee bean sign".
CT abdomen and pelvis, axial section (Fig. 2a) and coronal section (Fig. 2b) show grossly dilated bowel loops with fluid levels in the region of the sigmoid.
Based on the radiological findings, laparotomy was indicated. At laparotomy, the sigmoid colon was grossly dilated, without any changes of gangrene.
The sigmoid loop was decompressed in its entirety (Fig. 3), followed by sigmoidopexy to prevent re-torsion.
A. Sigmoid volvulus is an abnormal twisting of the sigmoid colon along its mesenteric axis that causes closed-loop obstruction and can lead to ischaemia, perforation, and death. Sigmoid volvulus is believed to account for 2–5% of cases of large-bowel obstruction, which places it third in prevalence after cancer and diverticulitis . Sigmoid volvulus is the result of a closed-loop obstruction around a fulcrum point. Genesis of sigmoid volvulus requires the twist of a mobile loop around a fulcrum point, this typically occurs when there is a mobile loop with an elongated mesocolon and a narrowed base, and hence both ends of the loop are close together. Mobile segments that can be involved include the sigmoid, transverse colon and even caecum, which is mobile in 11–25% of the general population. Predisposing factors include congenital or acquired anatomical variations, such as a long redundant sigmoid with an elongated mesentery, a history of abdominal surgery, late-pregnancy and patient history factors, such as mental retardation, a high-fibre diet, chronic constipation and coincidental disease .
B. Sigmoid volvulus has a wide range of presentations ranging from a dramatic acute onset with abdominal pain and intestinal obstruction to recurrent minor episodes of intermittent partial volvulus in which the patients may be relatively asymptomatic. In addition, patients with acute complete sigmoid volvulus are believed to have mild recurrent episodes of partial sigmoid volvulus previously, which have resolved spontaneously .
C. Plain abdominal radiographs demonstrate a large, dilated loop of colon with inverted U shape showing the classic "coffee bean appearance". There may be few air-fluid levels.
Specific signs include:
- Coffee bean sign
- Frimann Dahl's sign - three dense lines that converge towards the site of obstruction and absent rectal gas .
Fluoroscopy: Although now uncommonly performed, a water-soluble contrast enema exquisitely demonstrates this condition, with the appearance described as the "bird of prey sign".
CT findings include a large gas-filled loop without haustral markings, forming a closed-loop obstruction.
Specific signs on CT:
- Whirl sign - twisting of the mesentery and mesenteric vessels
- Beak sign - if rectal contrast has been administered .
D. Operative techniques such as primary sigmoid resection and anastomosis, sigmoidopexy, and percutaneous endoscopic colostomy have been used to manage sigmoid colon volvulus .
Differential Diagnosis List
Large bowel obstruction