Meconium ileus usually results from cystic fibrosis.
Typically, newborns vomit, have an enlarged abdomen, and do not have a bowel movement during the first several days of life.
The diagnosis is based on symptoms and x-ray results.
The blockage is treated with enemas, and surgery is needed if enemas do not work.
Meconium, a dark green substance, is a newborn's first stool. Newborns expel meconium almost always in the first 24 hours of life. If the meconium is abnormally thick or tarlike, it can block the last part of the small intestine, called the ileum. This blockage is referred to as meconium ileus. Above the blockage, the small intestine is enlarged (dilated), resulting in abdominal swelling (distention). Below the blockage, the large intestine (colon) is narrow (called microcolon) because nothing is passing through it.
Causes of Meconium Ileus
Meconium ileus is most often an early sign of cystic fibrosis Cystic Fibrosis (CF) Cystic fibrosis is a hereditary disease that causes certain glands to produce abnormally thick secretions, resulting in tissue and organ damage, especially in the lungs and the digestive tract... read more . Cystic fibrosis is an inherited disorder that causes intestinal secretions to be abnormally thick and sticky, and the secretions stick to the lining of the intestine, causing an obstruction of the small intestine. These extremely sticky secretions are the first indication of illness in 10 to 20% of children with cystic fibrosis. Newborns with meconium ileus almost always develop other symptoms of cystic fibrosis later.
Meconium plug syndrome Meconium Plug Syndrome Meconium plug syndrome is blockage of the large intestine with thick intestinal contents (meconium). Meconium plug syndrome may result from Hirschsprung disease or cystic fibrosis. Typically... read more is similar to meconium ileus except that it is the large intestine that is blocked by meconium.
Complications of meconium ileus
Meconium ileus is sometimes complicated by
Perforation of the small intestine
Twisting of the intestine on itself
The small intestine can perforate or tear because it is very distended or because the dilated small intestine has twisted on itself (volvulus Intestinal Obstruction An obstruction of the intestine is a blockage that completely stops or seriously impairs the passage of food, fluid, digestive secretions, and gas through the intestines. The most common causes... read more ), which blocks the intestine's blood supply.
Perforation Perforation of the Digestive Tract Any of the hollow digestive organs may become perforated (punctured), which causes a release of intestinal contents and can lead to sepsis (a life-threatening infection of the bloodstream) and... read more is a dangerous condition because it causes meconium to leak into the abdominal cavity. If perforation occurs before birth, the affected part of the small intestine may be shrunken and narrow (intestinal atresia), which may require surgery after birth. If perforation occurs after birth, leakage of meconium causes inflammation and infection (peritonitis Peritonitis Abdominal pain is common and often minor. Severe abdominal pain that comes on quickly, however, almost always indicates a significant problem. The pain may be the only sign of the need for surgery... read more ), which can lead to shock and death.
Symptoms of Meconium Ileus
After birth, newborns usually pass meconium in the first 12 to 24 hours. However, newborns with meconium ileus do not pass meconium within this time frame and also have symptoms of intestinal blockage, including vomiting and abdominal swelling.
Doctors may be able to feel enlarged loops of small bowel through the abdominal wall.
Diagnosis of Meconium Ileus
Before birth, prenatal imaging tests
After birth, symptoms of intestinal blockage
Abdominal x-rays and sometimes contrast enema
Tests for cystic fibrosis
If doctors do a prenatal ultrasound Ultrasonography Prenatal diagnostic testing involves testing the fetus before birth (prenatally) to determine whether the fetus has certain abnormalities, including certain hereditary or spontaneous genetic... read more , they sometimes can see signs that the fetus's intestine is blocked.
However, doctors usually first suspect the diagnosis after birth, when the newborn has symptoms of intestinal blockage. Doctors strongly suspect meconium ileus if the newborn has a family history of cystic fibrosis or if routine newborn screening tests Newborn Screening Tests Screening tests are done to detect health conditions that are not yet causing symptoms. Many serious disorders that are not apparent at birth can be detected by various screening tests. Early... read more are positive for cystic fibrosis.
If doctors suspect meconium ileus, they do abdominal x-rays, which show enlarged loops of the small intestine. Sometimes they also take x-rays after giving an enema using a liquid substance that is visible on x-rays (radiopaque contrast agent X-rays with a radiopaque contrast agent X-rays are a type of medical imaging that use very low-dose radiation waves to take pictures of bones and soft tissues. X-rays may be used alone (conventional x-ray imaging) or combined with... read more ). The enema shows that the colon is narrower than normal (called a microcolon) and that there is a blockage near the end of the small intestine.
Treatment of Meconium Ileus
Infants who have a perforated or twisted intestine need immediate surgery.
If there is no perforation or twisting, doctors try to wash out the meconium blockage using an enema. The enema may contain N-acetylcysteine, which breaks down and softens the thick meconium to allow it to pass through the intestine and out the rectum.
If the enema does not remove the blockage, doctors do surgery to cut open the intestine and remove the meconium. Usually they bring the open ends of the intestine out through the wall of the abdomen (ileostomy). They do more enemas through the open ends of the intestine until the meconium is completely removed. Later, the doctors do another operation to put the ends of the intestine back together.
After the blockage is removed and stool begins passing through the area, the narrowed colon eventually widens out to its normal diameter.