Volvulus

Etiology

Volvulus is associated with intestinal malrotation, an enlarged colon, a long mesentery, Hirschsprung disease, pregnancy, abdominal adhesions, and chronic constipation. In adults, the sigmoid colon is the most commonly affected part of the gut, followed by the cecum. In children, the small intestine is more commonly involved.[2] In most cases, sigmoid volvulus is an acquired disorder. On the other hand, cecal volvulus may occur due to incomplete dorsal mesenteric fixation of the right colon or cecum or an elongated mesentery. Sigmoid volvulus is more common in individuals with neuropsychiatric disorders, multiple sclerosis, and Parkinsons disease.

Neuroleptic drugs can also interfere with colonic motility and may trigger volvulus. Nursing home patients who are bedridden and have chronic constipation have a greater risk of developing sigmoid volvulus. A higher incidence of volvulus is also noticed among patients with associated myopathy like Duchene muscular dystrophy or visceral myopathy. In developing countries, a high-fiber diet leads to overloading of the sigmoid colon, causing it to twist around the mesentery. Similarly, Chagas disease or megacolon can also predispose to sigmoid volvulus. Rarely, appendicitis or surgery may lead to excessive adhesions leading to volvulus.

Epidemiology

Colonic volvulus constituted nearly 2% of all the cases of bowel obstructions admitted in the United States between 2002 and 2010. Sigmoid volvulus, accounting for 8% of all intestinal obstructions, occurs between the third and the seventh decades of life. This condition is more frequent in older men, Black individuals, adults with chronic constipation, and those with associated neuropsychiatric disorders. On the other hand, cecal volvulus is more common in younger women.[3] The age group of midgut volvulus is strikingly different from colonic volvulus; it is typically seen in babies with rotation anomalies of the intestine. Segmental volvulus of other gut portions can occur in people of any age, usually because of abnormal intestinal contents or adhesions. 

Pathophysiology

Sigmoid volvulus is typically caused by 2 mechanisms: chronic constipation and a high-fiber diet. In both instances, the sigmoid colon becomes dilated and loaded with stools, making it susceptible to torsion. The direction of the volvulus is counterclockwise. With repeated attacks of torsion, there is a shortening of mesentery due to chronic inflammation. Subsequently, adhesions develop, which then entrap the sigmoid colon into a fixed twisted position. Cecal volvulus can be either organoaxial (cecocolic or true cecal volvulus) or mesentericoaxial (cecal bascule). In the organoaxial variety, the ascending colon and distal ileum twist around each other clockwise. However, in the mesentericoaxial sub-type, the caecum is not completely fixed and is located anteriorly over the ascending colon at a right angle to the mesentery. Since there is no twisting of the vascular pedicle, vascular compromise is rarely associated with cecal volvulus.[4] In contrast to colonic volvulus, midgut volvulus in children is invariably due to rotation anomalies of the intestine.[5] 

History and Physical

Patients with sigmoid volvulus are usually older adult men with a history of chronic constipation. Although most patients have an acute onset of symptoms, nearly one-third may have an insidious presentation. Signs and symptoms of volvulus include abdominal pain, distension, vomiting, constipation, obstipation, hematochezia, or fever.[6] Patients presenting to the hospital after a significant delay may have diffuse tenderness, guarding, and rigidity, suggesting perforation peritonitis. In severe abdominal distension, patients often develop hemodynamic instability and respiratory compromise. In contrast, newborns with midgut volvulus have sudden onset bilious emesis, upper abdominal distension, hematochezia, or inconsolable crying. Older children with midgut volvulus may also present with features including episodic abdominal pain, diarrhea, and failure to thrive.[5] 

Evaluation

Diagnosis of colonic volvulus is clinical; however, radiological investigations are often required for diagnostic confirmation due to overlapping clinical features with other diseases. The first investigation to be performed is a plain radiograph of the abdomen. Specific signs, including a "bent inner tube" or a "coffee bean" sign, are characteristics of sigmoid volvulus. These refer to the appearance of the air-filled closed loop of the colon, which forms the volvulus, revealing a thick inner and a thin outer wall. Similarly, plain radiographs of cecal volvulus patients reveal distended small and large bowel. Contrast enema should be performed only after perforation peritonitis is ruled out. Demonstration of a "bird's beak" at the point where the colon rotates to form the volvulus is characteristic of sigmoid volvulus. 

Computed tomography of the abdomen and pelvis is generally not indicated in patients with colonic volvulus, however, when performed an upward displacement of the appendix with large and small bowel obstruction is suggestive of cecal volvulus.[7] Similar to colonic volvulus, in children with midgut volvulus, radiological features include a paucity of gas throughout the intestine with few scattered air-fluid levels on plain radiograph and an abnormally placed duodenojejunal junction with the small bowel looping entirely on the right side of the abdomen on upper gastrointestinal series.[5] Laboratory studies, including complete blood count and serum biochemistry, may show a left shift with leucocytosis and electrolyte abnormalities. However, these are non-specific. 

Treatment / Management

In all the cases of volvulus, patients need to be resuscitated before surgery. Broad-spectrum antibiotics should also be administered in these patients preoperatively. Vitals monitoring, including measurement of the urine output, should be done periodically. Some clinicians also advocate nursing the patient in a left lateral position to avoid compression over the vena cava. The initial treatment for sigmoid volvulus is sigmoidoscopy, which can also help in establishing a diagnosis of sigmoid volvulus. Spiraling of the mucosa and difficulty negotiating the scope beyond the site of obstruction are classical features of sigmoid volvulus on sigmoidoscopy.[8] For endoscopic treatment, gentle insertion of the endoscope just below the site of torsion and air insufflation is attempted. If unsuccessful, the endoscope tip can be used to follow the twisted mucosa and reach the apex. Alternatively, a soft flatus tube or red rubber tube can be inserted. This leads to detorsion and decompression. The success rate of sigmoidoscopic reduction lies between 50% to 100%.[8] A flatus tube is kept in situ after the endoscopic reduction to prevent an early recurrence. Due to a high recurrence rate, a bowel resection within 2 days is recommended. Contraindications to endoscopic reduction include suspicion of bowel gangrene manifesting as fever, persistent hematochezia and features of sepsis, and perforation peritonitis. Immediate resuscitation and surgery are recommended in these cases. 

Surgical options for sigmoid volvulus include bowel resection and bowel conservative surgery. Bowel resection is recommended over conservative surgery (sigmoidopexy or mesenteric plication) as recurrence rates are higher with the latter. If there is no faecal peritonitis, a primary resection can be done. If there is bowel perforation, then a Hartmann procedure can be performed. A minimally invasive approach for sigmoid volvulus can be considered depending on the surgeon's preference and experience. Older adult patients may benefit from minimally invasive procedures.[9]

Endoscopic decompression for cecal volvulus has low success rates (nearly 20%) and is also associated with high recurrence rates. In a cecal volvulus, the cecum can be detorsed and cecopexy can be performed. However, a part of the cecum often needs to be removed. The ideal procedure for cecal volvulus right hemicolectomy. If the bowel is necrotic, then resection with an ileostomy or a colostomy is necessary. If the patient is critically ill and is not fit for general anesthesia, a percutaneous tube cecostomy can be performed as an interim procedure. A definite procedure can be attempted when the anesthesia team declares the patient fit. 

Differential Diagnosis

The differential diagnoses for volvulus include the following:

• Abdominal hernia
• Appendicitis
• Acute mesenteric ischemia
• Colon cancer
• Constipation
• Colonic polyps
• Diverticulitis
• Intestinal perforation
• Intestinal pseudo-obstruction
• Intussusception
• Megacolon, chronic
• Megacolon, toxic
• Mesenteric artery ischemia
• Ogilvie syndrome
• Pseudomembranous colitis
• Rectal cancer

Prognosis

Any delay in the diagnosis of cecal or sigmoid volvulus can be associated with high morbidity and mortality. Mortality rates appear to be much higher for cecal volvulus than sigmoid volvulus. When volvulus is treated non-surgically, recurrence rates are very high, approaching 40% to 60%. When surgery is done in unstable patients, mortality rates of 12% to 25% have been reported.

Complications

If untreated, volvulus can cause bowel strangulation, gangrene, perforation, and peritonitis. Complications of surgery include the following:

• Recurrence (if conservative surgery is performed)
• Anastomotic leak
• Wound infection
• Pelvic abscess
• Sepsis
• Fecal fistula
• Complications of colostomy and/or ileostomy