The name of this disease is derived from necrotizing, meaning damage and death of cells, entero, referring to the intestine, and colitis, meaning inflammation of the colon (lower part of the intestine). It can affect any portion of the gastrointestinal tract or the entire gastrointestinal tract.
Necrotizing enterocolitis is the most common gastrointestinal emergency in the neonatal intensive care unit. It develops in 2,000 to 4,000 newborns annually and affects 1% to 8% of all newborns admitted to neonatal intensive care units in North America. Newborns with birth weights less than 2,000 grams (approximately 4 1/2 pounds) comprise 80% of necrotizing enterocolitis cases.
While there appears to be no single cause of necrotizing enterocolitis, research has identified a number of risk factors, with prematurity being the most significant. Necrotizing enterocolitis predominantly affects premature infants, but is also seen in full-term infants. Although necrotizing enterocolitis usually occurs 3 to 12 days after birth, late onset can occur many weeks after birth.
Damage to the intestinal tissues can lead to a perforation in the intestines, allowing the bacteria normally present in the intestinal tract to leak out into the abdomen and cause infection. The damage may exist only in a small area or it may progress quickly to large areas of the intestine.
Infection in the intestines can be life-threatening, and even with treatment there may be serious complications, such as severe infection in the abdomen, a perforation in the intestine, and scarring or narrowing of the intestine. Patients who must undergo removal of a large segment of intestine also experience problems with food absorption.
Since the early symptoms of necrotizing enterocolitis may resemble other digestive conditions or medical problems, this disease is often difficult to diagnose. However, symptoms may include the following:
Physical examination generally reveals abdominal distention (swelling) and progressive abdominal tenderness. In some cases, a mass can be felt, indicating an area of perforated bowel. In other cases, a redness of the abdominal wall can be seen. This may also indicate perforation and inflammation of the membrane lining the abdominal cavity (peritonitis).
When necrotizing enterocolitis is suspected, abdominal X-rays are taken. An X-ray may show multiple small bubbles within the wall of the intestine (pneumatosis intestinalis). Repeated X-rays help to assess disease progression. In severe cases, the X-ray may reveal air or gas in the large veins of the liver. This air is produced by bacteria in the wall of the bowel. If the bowel is perforated, air may be seen outside the intestine, but within the abdominal cavity.
The management of necrotizing enterocolitis depends on the severity of the disease, the infant's response to medical treatment, and the degree of bowel involvement. Sixty to 80 percent of babies with necrotizing enterocolitis are managed medically and symptoms resolve without surgery.
Newborns with necrotizing enterocolitis that does not show indications for surgery are placed on a medical protocol. This protocol includes:
Approximately 50% of infants with necrotizing enterocolitis who receive nonoperative treatment have clinical resolution of their disease. They experience good recovery and are able to lead normal lives. Nevertheless, these infants often have complications such as intestinal stricture (narrowing), usually in the colon. This complication may require later corrective surgery and can occur even when medical management has been successful.
If medical management fails or if the bowel is perforated, surgery becomes necessary. During surgery, the pediatric surgeon may find a swollen, discolored bowel with several areas that have died due to a lack of blood supply, or the entire bowel may be involved. The aim of surgery is to remove only the bowel that has died and to leave any segments of the bowel that are likely to recover. A temporary opening in the wall of the abdomen, which is called an ostomy, is created to allow the bowel to recover and heal. Another operation to re-examine the abdomen may be required 24 to 48 hours later to determine if disease has progressed. In some cases, a drain is initially placed in the abdomen to remove the infected fluid and help stabilize the infant prior to more definitive surgery.
Of the newborns who undergo surgery, approximately two-thirds survive. The mortality rate is higher in infants with very low birth weights, particularly those with extensive necrosis of the bowel and overwhelming infection. At least 10% of children who are managed surgically have gastrointestinal problems, including short-gut syndrome, fat malabsorption, or intestinal strictures. The severity of these conditions correlates with the severity of their necrotizing enterocolitis.
Although limited information is available to evaluate the neurodevelopmental implications of necrotizing enterocolitis, long-term follow-up data indicate that up to 50% of infants who survive are developmentally impaired or delayed.