Intussusception

Intussusception is a medical emergency in which one portion of the intestine (bowel) slides or “telescopes” into another section of bowel, cutting off the blood supply and blocking the flow of materials through the digestive system.

In the process of intussusception, one part of the intestine infolds into another section the intestine. The most common place for this to occur is at the junction where the end of the small intestine (the ileum) meets the large intestine (the colon). Here, the small intestine slides into the large intestine. Occasionally one part of the small intestine will slide into another part of the small intestine, but this is much less common.

Once the infolding begins, the blood supply to the intestines and the tissue (mesentery) that surrounds and holds them in place is cut off. The intestines are a long tube. The infolding tissue creates an obstruction that blocks the passage of material through the intestine. The walls of the intestine and the surrounding tissue begin to swell, increasing the blockage. The intestine may bleed or rupture, and eventually gangrene develops as the tissue dies.

Intussusception occurs most often in infants and toddlers. It is the leading cause of intestinal obstruction in children ages 3 months to 5 years. The highest rate of intussusception occurs in children ages 3 to 12 months. Two-thirds of cases occur before the child's first birthday. Intussusception is the leading cause of abdominal surgery in children age 5 and younger.

As infants, three boys develop intussusception for every two girls that do, but as children age, the rate changes sharply and the disorder becomes much more common in boys. By age 4, the boy:girl ratio is 8:1. There is no difference in the rate of intussusception among races or ethnic groups. Internationally, although few statistics are available, the rate seems to be about the same as in the United States.

Adults can develop intussusception, but the condition is rare.

Another theory of why intussusception develops suggests that the process is set off by uncoordinated bowel contractions (peristalsis). Viral infection may also play a role. There is an association between recent viral infection and intussusception, but no clear cause and effect relationship has been determined. At one time, it appeared that vaccination for rotavirus, a virus that causes severe diarrhea in young children, increased the rate of intussusception. The vaccine in question was withdrawn from the U.S. market. Its replacement vaccine, RotaTeq, has been found in some studies to show a slight association with increased intussusception rates in certain populations, but there have been no definitive patterns, and the benefits far outweigh the risk.

Intussusception is a medical emergency. Symptoms of intussusception usually appear suddenly in an otherwise healthy child. The classic symptoms of intussusception are abdominal pain, vomiting, and passing reddish, jelly-like stools called “currant jelly” stools. The jelly-like material comes from a shedding of mucus from the intestinal wall, and the red is from fresh blood. However, this constellation of three symptoms is present in only about 20% of children. About 50% of children have abdominal pain and currant jelly stools without vomiting.

An infant with intussusception appears healthy but may suddenly draw up his or her legs and scream or cry frantically in pain. The child may vomit. This is followed by a period when the pain disappears and the child appears normal. Painful episodes return, however, at roughly 10–20 minute intervals. The child may have loose watery stools at first. Over time, the stools become reddish and jelly-like. Eventually the child becomes lethargic between bouts of pain and may develop a swollen abdomen and fever. If left untreated, intussusception is fatal.

Adults can also experience intussusception, although the disorder is uncommon to rare. In adults, the cause is often an unsuspected tumor or polyp growing in the intestine. Symptoms often appear much more gradually in adults and may come and go over a long period. Adult symptoms of intussusception include changes in bowel frequency, urgent desire to have a bowel movement, abdominal cramps, pain in a single area of the abdomen, rectal bleeding, nausea, and vomiting. These symptoms resemble the symptoms of other gastrointestinal disorders, complicating diagnosis.

Diagnosis is made on the basis of patient history and imaging studies. X-ray images of the abdominal region will show a mass or obstruction in the bowels. Computed tomography (CT) scans or ultrasound may be done in addition to x-rays. If there is no sign that the bowel has torn (perforated) or ruptured, a contrast x-ray is done on the large intestine. In a contrast colon x-ray, a liquid containing barium is inserted through the rectum and into the colon. The barium contrasts with the surrounding tissue to provide clearer x-ray images of the affected area.

Diagnosis of intussusception sometimes results in treatment. Forcing barium into the colon may reduce the intussusception as pressure from the barium pushes the infolded piece of bowel back out of the large intestine. This occurs in as many as 75% of cases. Sometimes the procedure needs to be repeated to get complete reversal of the infolding. When a barium enema provides effective treatment, the pain stops immediately and the child becomes dramatically better. The child is usually hospitalized for observation for about 18–24 hours. This precaution is taken because most recurrences of the intussusception occur within that time.

If the initial x-rays show that the bowel has ruptured or has a perforation or if massive infection is present (peritonitis), a barium enema cannot be used and emergency surgery is required. Surgery is also required if the barium enema is ineffective in reversing the blockage. About 25% of children require surgery. Recovery after surgery is usually complete and no complications are expected.

Individuals whose intussusception is successfully treated without surgery can return to a normal diet immediately. Individuals who require surgery will initially be fed intravenously (IV), followed by a clear liquid diet, then progressing to soft foods until normal bowel function is established. At this time they can return to their regular diet.

Untreated intussusception is fatal, usually within two to five days. Death is caused by complications from gangrene and massive infection. Individuals who are successfully treated for intussusception usually recover without complications. Repeat intussusception can be as high as 10% in individuals whose intussusception is cleared by barium enema. Most of the time, if there is a recurrence it happens within the first 24 hours, although a longer time frame is always possible.

There is no way to prevent intussusception. However, prompt medical care can prevent death.

Tish Davidson, AM