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Colonic Volvulus

Sean C. Glasgow, MD, FACS

San Antonio Military Medical Center

Fort Sam Houston, TX

 

Volvulus involves a twisting of any hollow viscus and can occur throughout the gastrointestinal tract. In the colon, volvulus can lead to obstruction and sometimes ischemia and perforation. Progressive proximal bowel distension occurs as a result of the obstruction, while gas distension of the closed loop increases intraluminal pressure over venous pressure leading to vascular congestion and eventual ischemia. Twisting of the mesenteric vessels can also produce arterial insufficiency and venous thrombosis. Ischemia affects the mucosa initially but can progress to full-thickness necrosis and perforation. The most common anatomic locations for volvulus in the colon are the non-fixed regions, specifically the cecum, sigmoid and occasionally transverse portions.

Etiology

 

By definition a sigmoid volvulus arises due to rotation around the mesentery (meso-axial), and it occurs in a counter-clockwise direction in 70% of patients. In order to volvulize, the sigmoid colon must be freely mobile and not tethered by peritoneal attachments, and the mesentery must be of sufficient length to permit at least 180 degrees of rotation. Additionally, the mesosigmoid root must be disproportionately narrow relative to the mesenteric length. In case-control studies, the ratio of mesenteric root width to overall length is the strongest anatomic predictor for volvulus. However, it is unclear whether this dolichomesocolic arrangement is congenital or acquired.

In support of a congenital etiology are the strong male predominance in endemic regions of the world and the persistently elevated incidence of volvulus among settlers who originate from those areas. However, sigmoid volvulus is very rare in children and young adults despite the presence of a relatively floppy colon during these ages, suggesting that other factors besides congenital colonic mobility are involved. In non-endemic areas of the world, chronic constipation is a strongly correlated risk factor. The increased fecal load is believed to dilate the sigmoid lumen and produce elongation of the mesentery. Likewise, in endemic regions, large amounts of dietary fiber prevent constipation but this undigested fiber may result in excessively bulky stools. Higher incidence is also observed after periods of fasting, with more cases of volvulus observed following bountiful harvests or the Muslim holy month of Ramadan. Ultimately, a cause-and-effect relationship between chronic constipation, excessive fecal burden and sigmoid volvulus is difficult to discern.

Other predisposing factors for sigmoid volvulus include various causes of megacolon. Congenital colonic aganglionosis (Hirschsprung’s disease) occasionally can produce the rare volvulus in children. In Brazil, trypanosomiasis (Chagas’ disease) causes degeneration of the myenteric neuronal plexus, chronic aperistalsis, and a reported incidence of volvulus approximating 27% of those infected. There also is some association between sigmoid volvulus and higher elevations. The lower atmospheric pressure at elevation creates an increased gradient relative to endoluminal pressure that may result in colonic distension. However this does not explain the male predilection in these regions. Others have hypothesized that the wider female pelvis permits more frequent spontaneous detorsion of the volvulus. Supporting this concept is the finding that sigmoid volvulus is the second most common cause of intestinal obstruction during pregnancy, and that the majority of these occur during the third trimester when the gravid uterus fills the pelvis.

Cecal volvulus results from either meso-axial or organo-axial rotation. When meso-axial, the rotation is typically around the ileocolic vessels, creating a volvulus comprised of ascending colon and terminal ileum, not just the cecum. Organo-axial rotation causes the cecal bascule, in which the cecum is flipped anteriorly over the ascending colon to produce obstruction at the ileocecal valve and a closed looped of proximal ascending colon. The major risk factor for either type of cecal volvulus is lack of peritonealization of the right colon, typically due to mobilization during prior abdominal or pelvic surgery. Other forms of colonic volvulus include ileo-sigmoid knotting, transverse colon volvulus and post-resection volvulus around an anastomosis. These comprise <1% of all cases.

Incidence

 

Although colonic volvulus is infrequent in North American and European populations, it accounts for the majority (up to 80%) of large bowel obstructions in certain areas of the world. The so-called “volvulus belt” extends across the equator and southern hemisphere from Brazil to sub-Saharan Africa, the Middle East, India, and Russia. In these regions, the male:female ratio for sigmoid volvulus is 4:1. The peak incidence occurs around 41 – 50 years of age. The younger age at presentation in endemic regions compared to Western countries helps explain the finding that mortality from sigmoid volvulus is actually higher in more developed countries. Furthermore, presentation of sigmoid volvulus in endemic areas is typically fulminant, leading to more timely surgical treatment compared to the more indolent course common to patients in the US. Unlike the sigmoid version, cecal volvulus does not follow any geographic distribution, although it is more prevalent in developed countries where patients are more likely to have had previous abdominal surgery.

Risk factors for sigmoid volvulus in the US include advanced age, male gender, and history of neuropsychiatric disease. African-Americans are also at slightly increased risk relative to Caucasians. Traditionally sigmoid volvulus was believed to account for approximately 60% of all colonic volvulus cases, with meso-axial cecal (35%) and cecal bascule (5%) comprising the remainder. However, a recent study from the University of Minnesota examining their 7-year experience with colonic volvulus in 92 patients challenges this belief. Swenson and colleagues found that cecal volvulus was actually more common, occurring in 57.6% of patients compared to only 42.4% with sigmoid volvulus. Females comprised 81% of those with cecal volvulus and tended to be younger and healthier. Conversely, sigmoid volvulus was more frequent in men (72%), with nursing home residency, chronic constipation and history of neurologic disorders being significant risk factors.

Diagnosis

 

Patients with colonic volvulus typically present with acute-on-chronic abdominal distension that may be insidious and develop over 3 – 4 days. They will report obstipation and loss of appetite. Nausea and emesis are late symptoms of the complete bowel obstruction, although early vagally-mediated emesis is reportedly a poor prognostic sign of colonic gangrene. Abdominal pain tends to be diffuse and non-focal until perforation, at which point peritoneal signs are apparent. Physical exam findings include a hypertympanitic abdomen. Tachycardia, peritoneal signs, lactic acidosis and multisystem organ failure are late findings that suggest colon ischemia. Urgent evaluation by the surgeon must include functional assessment of the anal sphincters, as patients with longstanding fecal incontinence may be best served with resection and colostomy.

Plain abdominal radiographs depicting a dilated, gas-filled loop of colon are suggestive of volvulus in up to 70% of cases. For sigmoid volvulus, the “bent inner tube” or “coffee bean” signs will show the loop pointing towards the right upper quadrant. The “northern exposure” sign occurs when the distended sigmoid loop extends cephalad to the transverse colon. Traditionally, contrast enema studies were the preferred method of diagnosing sigmoid volvulus, with the “bird’s beak” appearance of the twisted rectosigmoid junction being diagnostic. However, instilling contrast under pressure rarely reduces the volvulus and may exacerbate mucosal ischemia. Obtaining these studies at night can also be difficult. For these reasons, barium enemas have been supplanted by computed tomography (CT) scanning.

The sensitivity of CT for diagnosing sigmoid volvulus is >95% and only slightly lower for cecal volvulus. In both instances, the “whirl” sign of the twisted mesocolon frequently is observed. Likewise, the “X marks the spot” sign represents the crossing of the superior and inferior transition points within the colon. Also commonly seen is the “split wall” sign, created by interposition of the mesenteric fat between two adjacent colonic walls. Evidence on CT of colonic pneumatosis, portal venous gas, free fluid or loss of bowel wall enhancement are all concerning for necrosis.

The differential diagnosis for sigmoid volvulus involves excluding other more common causes of large intestinal obstruction, including neoplasm and diverticular stricture, as well as other etiologies of abdominal pain such as diverticulitis, mesenteric ischemia, and colonic pseudo-obstruction (Ogilvie’s). More likely to occur in younger and female patients, cecal volvulus should be differentiated from appendicitis, ruptured ovarian cyst or pelvic inflammatory disease, inflammatory bowel disease and the various causes of distal small bowel obstructions.

All patients with suspected colonic volvulus require aggressive IV fluid resuscitation, as dehydration from fluid sequestration is common. Electrolyte derangements should be corrected. Nasogastric tube and Foley placement are also indicated. Empiric antibiotics covering gut flora are reasonable for patients with suspected colon ischemia, and for those who require operative intervention or with a history of cardiac valve abnormalities or implanted hardware.

Management – Sigmoid Volvulus

 

Colonoscopy and attempted endoscopic detorsion of the sigmoid volvulus should be the initial therapeutic step for all patients without suspected frank necrosis. Although the transition is often within 20 cm of the anal verge and thus reachable by a rigid proctoscope, the fiber optic colonoscope provides better visualization and the ability to easily aspirate and irrigate. The endoscope is gently inserted with minimal insufflation. Once at the spiral transition point of the volvulus, gentle pressure is applied and the scope advanced through the volvulus. There is typically a rush of gas and fluid as the closed loop is decompressed. Careful inspection of the mucosa can determine whether ischemia has occurred. Endoscopic detorsion is successful in 70 – 90% of patients with sigmoid volvulus. Some surgeons advocate placement of a long rectal tube in an attempt to prevent immediate re-volvulization. However, scant data exists supporting this practice and most patients will undergo semi-elective surgery within 48 – 72 hours.

Immediate laparotomy is indicated for cases when endoscopic detorsion is not successful or in patients with signs and symptoms suggestive of full-thickness necrosis. The volvulized sigmoid should be resected back to viable margins and any contamination thoroughly irrigated from the peritoneal cavity. Whether to perform a Hartmann’s procedure or resect and anastomose with a diverting stoma are surgeon- and patient-dependent. Even with prompt surgical treatment the mortality rate for colonic gangrene ranges from 30 – 52%.

Following successful detorsion, some authors have advocated observation alone for poor surgical candidates. Older literature reports that 83% of elderly patients with sigmoid volvulus will die within 2 years from other causes, and the true incidence of recurrent sigmoid volvulus is not known. Recurrence rates in the medical literature range from 25 – 90%. However, non-operative therapy in the University of Minnesota experience failed in 48% of patients with a median time to recurrent volvulus of 106 days (range 8 – 374 days). Thus, most suitable patients should undergo semi-elective sigmoidectomy with primary anastomosis after their initial presentation. This can often be accomplished through a limited midline laparotomy or transverse celiotomy, since the sigmoid colon is markedly redundant and its usual peritoneal fixation is lacking. Likewise, a generous mesenteric resection is not required. The expected mortality rate for non-emergent sigmoid resection in this population is approximately 10% and the recurrence rate <5%.

Given the significant medical co-morbidities present in patients with sigmoid volvulus, there is continuing interest in developing minimally invasive approaches. Several authors have reported the use of percutaneous endoscopic colostomy (PEC) devices. The concept is to provide fixation at two separate positions within the redundant sigmoid using PEC tubes to prevent re-torsion (a third fixation point is naturally provided by the mesenteric root). Similar to percutaneous gastrostomy tubes, the PEC tubes are placed endoscopically using an over-the-wire technique. The required duration for the PEC tubes is unknown; while they have been removed as early as 8 weeks post-procedure, there are reports of recurrent volvulus upon removal of PEC tubes 7 months after placement. Others have combined laparoscopic visualization with these endoscopic fixation devices in order to prevent inadvertent mesenteric injury and ensure the correct orientation of the sigmoid colon. The downside to this approach is the requirement for general anesthesia. Long-term outcomes using these techniques do not exist, but the recurrence rate for the largely historical procedure of open sigmoidopexy range from 25 – 40%.

Management – Cecal Volvulus

 

Unlike in the sigmoid colon, cecal volvulus is less likely to be successfully detorsed by colonoscopy.  Swenson et al. attempted endoscopic reduction in 9.8% of patients with cecal volvulus, with no reported successes (0 for 5). Thus, any patient with cecal volvulus should proceed to the OR following resuscitation. The gold standard of treatment for either meso-axial volvulus or bascule is right hemicolectomy. In cases of frank colonic necrosis, care should be taken to avoid detorsion of the volvulus prior to obtaining vascular control in order to prevent the systemic release of potential toxins and translocated bacteria. Conversely, viable colon can be de-torsed, typically in a clockwise direction, to facilitate colectomy. Due to the nature of cecal volvulus (around the ileocolic vasculature), a significant length of terminal ileum may require resection. Ileocolic anastomosis can almost always be performed. In an unstable patient with colon gangrene, a prudent approach may be to resect and leave the bowel ends in discontinuity, temporarily close the abdomen and proceed with further resuscitation, then return to the OR in 1 – 2 days to restore continuity.

Both cecostomy and surgical cecopexy have been described. These techniques have the advantage of avoiding an anastomosis. However, placing sutures or a colostomy tube in the thin-walled cecum is difficult, and both procedures are associated with a not insignificant rate of fecal fistulization and infectious complications. The reported recurrence rates of these approaches are 0 – 30%, whereas recurrence is unheard of following formal resection. Additionally, given the low mortality rate of <5% in patients treated with right hemicolectomy, little is gained with these non-resectional techniques in terms of overall survival.

Conclusions

 

Volvulus of the cecum or sigmoid colon affects distinct patient populations and requires timely diagnosis and treatment to achieve good outcomes. CT imaging is the diagnostic modality of choice for these patients. An initial attempt at endoscopic reduction is indicated for sigmoid volvulus, however, it’s unlikely to successfully reduce a cecal volvulus. Most patients can be safely treated with resection and anastomosis of the involved segment of colon, although newer and less invasive techniques hold promise. Ultimately, the major predictors of poor outcome remain the common significant patient co-morbidities and the presence of gangrenous colon.

Suggested Reading

 

1. Akinkuotu A, Samuel JC, Msiska N, Mvula C, Charles AG. The role of the anatomy of the sigmoid colon in developing sigmoid volvulus: a case-control study. Clin Anat. 2011;24:634-637.

2. Gordon-Weeks AN, Lorenzi B, Lim J, Cristaldi M. Laparoscopic-assisted endoscopic sigmoidopexy: a new surgical option for sigmoid volvulus. Dis Colon Rectum. 2011;54:645-647.

3. Levsky JM, Den EI, DuBrow RA, Wolf EL, Rozenblit AM. CT findings of sigmoid volvulus. AJR Am J Roentgenol. 2010;194:136-143.

4. Mullen R, Church NI, Yalamarthi S. Volvulus of the sigmoid colon treated by percutaneous endoscopic colostomy. Surg Laparosc Endosc Percutan Tech. 2009;19:e64-e66.

5. Raveenthiran V, Madiba TE, Atamanalp SS, De U. Volvulus of the sigmoid colon. Colorectal Dis. 2010;12:e1-17.

6. Rosenblat JM, Rozenblit AM, Wolf EL, DuBrow RA, Den EI, Levsky JM. Findings of cecal volvulus at CT. Radiology. 2010;256:169-175.

7. Swenson BR, Kwaan MR, Burkart NE, et al. Colonic volvulus: presentation and management in metropolitan Minnesota, United States. Dis Colon Rectum. 2012;55:444-449.