(Congenital Megacolon; Hirschsprung's Disease)
(See also Overview of Digestive Tract Birth Defects.)
In Hirschsprung disease, a section of the large intestine is missing the nerve network that controls the intestine's rhythmic contractions. Symptoms of intestinal obstruction occur.
This defect affects the large intestine so that normal bowel contractions do not occur.
Typical symptoms include delayed passage of meconium in the newborn, vomiting, refusing to eat, and a swollen abdomen in later infancy.
The diagnosis is based on a rectal biopsy and measurement of the pressure inside the rectum.
Surgery is done to restore the normal passage of food through the intestines.
The large intestine depends on a network of nerves within its walls to synchronize rhythmic contractions and move digested material toward the anus, where the material is expelled as feces. In Hirschsprung disease, the affected section of intestine cannot contract normally. Without these normal contractions, material in the intestines builds up. Sometimes, Hirschsprung disease can lead to life-threatening enterocolitis, which is inflammation of the large intestine (colon).
Normally, 98% of newborns pass a dark green fecal material called meconium in the first 24 hours of life. Delayed passage of meconium raises the suspicion of Hirschsprung disease.
Later in infancy, children with Hirschsprung disease can have symptoms that suggest intestinal obstruction, such as bile-stained vomit, a swollen abdomen, and refusal to eat. If only a small section of the intestine is affected, a child may have milder symptoms and may not be diagnosed until later in childhood. These children may have ribbonlike stools and a swollen abdomen, and they often fail to gain weight. In rare cases, constipation is the only symptom.
Hirschsprung enterocolitis causes sudden fever, a swollen abdomen, and explosive and, at times, bloody diarrhea.
Initially, a barium enema is done to evaluate the defect. During a barium enema, the doctor instills barium and air into the child's rectum and then takes x-rays.
Rectal biopsy (removal of a piece of tissue from the rectum for examination under a microscope) and measurement of the pressure inside the rectum (manometry) are the only tests that can be used reliably to diagnose Hirschsprung disease.
Severe Hirschsprung disease must be treated quickly to lower the risk of enterocolitis.
Hirschsprung disease is usually treated with surgery to remove the abnormal section of intestine and to connect the normal intestine to the rectum and anus.
In some cases (for example, if the child is quite ill), the surgeon connects the lower end of the normal part of the intestine to an opening made in the abdominal wall (colostomy). Stool can thus pass through the opening into a collection bag, restoring normal movement of food through the intestines. The abnormal section of intestine is left disconnected from the rest of the intestine. When the child is older and healthier, the colostomy is closed, the abnormal section of intestine is removed, and the normal part of the intestine is reconnected to the rectum and anus in a so-called pull-through procedure.
Children who develop Hirschprung enterocolitis are hospitalized and are given fluids and antibiotics by vein. Then a long, thin tube is passed through the nose and placed in the stomach or intestine (nasogastric tube) and another tube is placed in the rectum. Saline is inserted into the rectum to wash away stool (called rectal irrigation) that has built up in the intestines. Surgery is done to remove the section of the intestines that is not functioning.