Volvulus refers to the twisting of a portion of the intestine around itself or a stalk of mesentery tissue to cause an obstruction. Volvulus occurs most frequently in the colon, although the stomach and small bowel can also twist. The part of the digestive system above the volvulus continues to function and may swell as it fills with digested food, fluid, and gas. A condition called strangulation develops if the mesentery of the bowel is twisted so tightly that blood flow is cut off and the tissue dies. This condition is called gangrene. Volvulus is a surgical emergency because gangrene can develop quickly, cause a hole in the wall of the bowel (perforation), and become life-threatening.
In the colon, volvulus most often involves the caecum and sigmoid segment. Sigmoid volvulus is more common than cecal volvulus.
Sigmoid Volvulus The sigmoid is the last section of the colon. Two anatomic differences can increase the risk of sigmoid volvulus. One is an elongated or movable sigmoid colon that is unattached to the left sidewall of the abdomen. Another is a narrow mesentery that allows twisting at its base. Sigmoid volvulus, however, can occur even without an anatomic abnormality.
Risk factors that can make a person more likely to have sigmoid volvulus are Hirschsprung's disease, intestinal pseudo-obstructions, and megacolon (an enlarged colon). Adults, children, and infants can all have sigmoid volvulus. It is more common in men than in women, possibly because men have longer sigmoid colons. It is also more common in people over age 60, in African Americans, and in institutionalized individuals who are on medications for psychiatric disorders. In addition, children with malrotation are more likely to get sigmoid volvulus.
The symptoms can be acute (occur suddenly) and severe. They include a bowel obstruction (commonly seen in infants), nausea, vomiting, bloody stools, abdominal pain, constipation, and shock. Other symptoms can develop more slowly but increase over time, such as severe constipation, lack of passing gas, crampy abdominal pain, and abdominal distention. A doctor may also hear increased or decreased bowel sounds.
Several tests are used to diagnose sigmoid volvulus. X rays show a dilated colon above the volvulus. Upper and lower GI series help locate the point of obstruction and show whether malrotation of the rest of the colon is present. A CT scan may be used to show the degree of twisting and malrotation, and whether perforation has occurred.
In most instances, a sigmoidoscope, a tube used to look into the sigmoid colon and rectum, can be used to reach the site, untwist the colon, and release the obstruction. However, if the colon is found to be twisted very tightly or is twisted so tightly that blood flow is cut off and the tissue is dead, immediate surgery will be needed to correct the problem and, if possible, restore the blood supply. Dead tissue will be removed during surgery, and a portion of the colon may be removed as well—a procedure called a resection. Sigmoid volvulus can recur after untwisting with the sigmoidoscope, but resection eliminates the chance of recurrence. Prompt diagnosis of sigmoid volvulus and appropriate treatment generally lead to a good outcome.
Cecal volvulus is the twisting of the caecum and ascending segment of the colon. Normally, the caecum and ascending colon are fixed to the internal abdominal wall. If not, they can move and become twisted. The main symptoms of cecal volvulus are crampy abdominal pain and swelling that are sometimes associated with nausea and vomiting.
In testing, x rays will show the caecum out of its normal place and inflated with trapped air. The appendix may be filled with gas, but little or no gas is seen in other parts of the colon. Upper and lower GI series will locate the volvulus and the position of the colon. A CT scan may show how tightly the volvulus is twisted. A colonoscopy, which uses a small, flexible tube with a light and a lens on the end to see the inside of the colon, can sometimes be used to untwist the volvulus. If the caecum becomes gangrenous or holes develop in it, surgery will be needed.