Colonic Volvulus

Tracey D. Arnell, MD
Assistant Professor of Surgery &
Associate Chief of Colon and Rectal Surgery
UCLA School of Medicine
Torrance, CA

Definition

Large bowel volvulus generally occurs when a non-retroperitonealized segment of the colon twists, or in the case of a cecal bascule, folds along its mesentery. This results in obstruction and, potentially, ischemia from compromise of the vascular supply as well as luminal distention with increased wall tension and decreased transmural blood flow.(1) Our knowledge regarding the etiology and treatment of patients with colonic volvulus comes from retrospective reports therefore, recommendations are quite variable.

Epidemiology

The prevalence of volvulus as a cause of large bowel obstruction varies greatly geographically, from 1-2% in the United States to nearly 80% in the Andes.(2,3) Colonic volvulus is a major cause of large bowel obstruction worldwide and accounts for the majority of cases of large bowel obstruction in the so called "volvulus belt" which includes Africa, the Middle East and Brazil.(1) In the United States, sigmoid volvulus occurs more frequently than cecal, and transverse and splenic flexure volvulus are quite rare.

There does not appear to be a strong gender predilection, although most series report a slightly higher occurrence in men. Colonic volvulus is extremely rare in children and adolescents and is usually associated with cystic fibrosis, Hirschsprung's, and chronic constipation are common comorbidities in this group.(4) It is likely that colonic volvulus is an acquired condition as is supported by its occurrence primarily in the older population. The mean age in the United States for sigmoid volvulus is in the 7th decade, and is approximately 10 years younger for cecal volvulus.(1,2,5)

Etiology

Colonic volvulus results when the bowel twists about the mesentery. In the sigmoid, the classic finding is a redundant sigmoid twisted on the narrow mesentery of the inferior mesenteric artery. In volvulus of the cecum, the bowel most commonly twists counterclockwise around the ileocolic artery, although this is variable. It may also fold upward, and this is known as a bascule. There must be a lack of retroperitoneal fixation for this to occur. This may be congenital; hence the reason it occurs at a younger age. Various studies have found that the cecum is mobile enough in 11-25% of the population to allow volvulus or bascule to occur.(6,7)

Causative or contributing factors to the development of volvulus are thought to include high fiber diets, chronic constipation, and altered colonic motility as a result of aging or medications (elderly and psychiatric patients). The most common cause of large bowel obstruction in pregnancy is cecal volvulus, perhaps as a result of the gravid uterus elevating the cecum.

Diagnosis

Patients with colonic volvulus typically present with abdominal distention and obstipation. Nausea and vomiting occurs with increasing duration and cecal location. A minority of patients are in shock suggesting perforation or bowel gangrene. Physical exam findings include distention, "splashing" bowel sounds, visible peristalsis on the abdominal wall in thin patients, and emptiness of the left iliac fossa specific to sigmoid volvulus.(11) A digital rectal exam must be performed to evaluate for the presence of a low rectal obstruction as a result of impaction, stricture or neoplasm. The presence of fever, hemodynamic alterations, and peritoneal signs are more likely with ischemia and perforation. The majority of studies report a higher incidence of ischemic changes with cecal volvulus (40%) compared to sigmoid (<30%), but this is highly variable.(5,8-10)

Plain abdominal radiographs are usually diagnostic (68-90%), especially in sigmoid volvulus. The finding of a coffee bean or bent inner tube with the apex pointing towards the left lower quadrant suggests a sigmoid volvulus. The "Northern exposure sign" in which the sigmoid colon is cephalad to the transverse colon has also been described.(12) Cecal volvulus is frequently accompanied by distended small bowel loops that are usually to the right of the colon. If the diagnosis is unclear based on plain films, computed tomography (CT) or a gastrograffin enema may be useful. Findings on contrast enema may include a "bird beak" at the point of torsion, or fluoroscopic evidence of detorsion. The CT scan will demonstrate the distended colon and the mesenteric twist is visualized as a "whirl".(13) Contrast enemas and endoscopy may be diagnostic and therapeutic and will be discussed with reference to management. Obviously in cases of peritonitis or suspected ischemia, no additional evaluation is necessary.

Treatment

There has been and remains much debate as to the safest, most effective treatment of colonic volvulus. The controversy revolves around the balance between minimizing procedural morbidity and preventing recurrence. The management and potential recurrence rates differ for cecal and sigmoid volvulus and will be discussed separately. In all cases, resection is mandatory if gangrenous changes are present.

Sigmoid Volvulus

Generally, ischemic changes are less frequent in cases of sigmoid volvulus, allowing for attempts at non-operative detorsion and consideration for less urgent surgery. Methods of detorsion include rigid proctoscope, flexible sigmoidoscopy and contrast enema, all of which are potentially diagnostic and therapeutic. The success rate for detorsion in most series approaches 90%.(9) Endoscopic methods are preferred as they allow for visualization of the mucosa for ischemic changes and allow passage of a tube to decrease the risk of early recurrence. When a rigid proctoscope is used, a thoracostomy tube may be used, and is of larger caliber than the catheters passed through the flexible endoscopes. If detorsion is unsuccessful, surgery is indicated. With successful decompression occurs, the question becomes the need for further surgical management. Documentation of recurrences in most studies is poor, but is likely >50% and increases with length of follow-up. Therefore, in all but the poorest risk patients, surgery is recommended.(2,5,8,9)

The options at the time of surgery include simple detorsion if unsuccessful preoperatively, suture pexy of the mesentery or sigmoid, resection with colostomy, and resection with primary anastomosis. Suture pexy, which may sound simple, can be very difficult in cases of a very redundant, distended colon. Obviously in cases of gangrenous bowel, resection is indicated. Mortality rates are lowest for non-resectional therapy, but are accompanied by high recurrence rates. Table 1 summarizes the procedures, advantages, disadvantages, and recurrence rates for the various procedures. Other factors that may influence the choice of surgery include patient's continence, the presence of a mega colon, which may increase the recurrence rate for segmental resection, and the mental status of the patients. Patients who are incontinent or otherwise unable to perform basic hygiene functions may be good candidates for creation of a stoma.

Table 1

Cecal Volvulus

Gangrenous changes in most series are more frequent in patients with cecal volvulus, as is an incorrect pre-operative diagnosis. For these reasons, these patients have traditionally undergone urgent or emergent operation. With the recognition that >50% of cases do not involve ischemic bowel, there has been an increase in the use of preoperative detorsion with contrast enemas or colonoscopy. There are high failure rates associated with these methods, though, and the benefit may be marginal. The recurrence rate for detorsion alone is unacceptably high (up to 75%), and the risk of gangrenous changes is significant; therefore, surgical intervention is almost always indicated.(5,14) Whereas preoperative detorsion of a sigmoid volvulus allows for decompression of a stool laden, distended proximal colon, this is unnecessary in cecal volvulus. Right colon resection or pexy is quite feasible and safe in the unprepped bowel. Surgical options depend on the viability of the cecum, but include cecopexy, cecostomy, and resection with stoma or anastomosis. As with sigmoid volvulus, the highest recurrence and lowest morbidity is with cecopexy, with the inverse true for resection. Again, cecopexy may be difficult in the presence of distended, thin or edematous colonic wall. Tube cecostomy is associated with significant complications including cecal necrosis, intraperitoneal leakage, difficult appliance placement with skin breakdown, and recurrence.

Other Colonic Volvulus

Volvulus of segments other than the sigmoid and cecum are very unusual. Reports consist of few patients and are anecdotal, therefore, it is not possible to make recommendations based on knowledge of recurrence risks and complications. As always, nonviable bowel should be resected.

Outcome

Mortality rates remain high for colonic volvulus, largely because patients tend to be elderly with significant comorbid conditions. In a recent large retrospective review of 228 patients, mortality for elective surgery in sigmoid volvulus was 6%, versus 24% for emergency procedures. The need for emergency surgery and the presence of gangrenous bowel were associated with increased morbidity and mortality. For cecal volvulus, Madiba et al reviewed 561 cases from the literature. The overall mortality was 18% for resection (viable 11% vs. non-viable 28%), and 15% for cecopexy and cecostomy.(5,9)

Conclusions

Colonic volvulus remains a significant cause of large bowel obstruction in the United States and throughout the world. Diagnosis is usually made based on clinical history, exam and plain abdominal films. If necessary, contrast enema and CT scan can be used. Endoscopy and contrast enema are potentially diagnostic and therapeutic, but are of limited use in cecal volvulus. In cases of peritonitis, shock or suspicion for gangrenous bowel, emergent surgery is performed without additional testing. In sigmoid volvulus, attempts at detorsion with placement of a decompressive rectal tube should be made, and are frequently successful. Because of high recurrence rates for detorsion alone, surgery is generally recommended. Operative management is determined based on the patient's general medical condition and the presence of ischemic bowel. Overall, surgical resection carries the lowest recurrence but has higher complication rates and mortality than pexy.

References

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