Intestinal atresia and stenosis involve narrowing or closure of the intestine. Food is blocked from passing through the intestine, which prevents normal feeding and intestinal function. Intestinal atresia and stenosis usually involve the small intestine, but can affect any part of the gastrointestinal tract.
Intestinal stenosis is a partial obstruction that causes the center opening of the intestine to become narrower, while intestinal atresia is a complete closure of the intestine.
There are different types of intestinal atresia, depending on where the closure occurs.
- Pyloric atresia – The obstruction is at the pylorus, which is the passage linking the stomach and the first portion of the small intestine (duodenum). Pyloric atresia is rare, and tends to run in families. Children with pyloric atresia vomit the contents of their stomachs; they also develop a swollen upper abdomen because of an accumulation of intestinal contents and gas.
- Duodenal atresia – The duodenum is obstructed. This is the first portion of the small intestine; it receives contents emptied from the stomach. Half of the infants with this condition are born prematurely; about two-thirds also suffer from cardiac, genitourinary, or other intestinal tract problems. Nearly 40% have Down syndrome. Infants with duodenal atresia usually vomit within hours after birth, and may develop a distended abdomen.
- Jejunoileal atresia – This involves an obstruction of the middle region (jejunum) or lower region (ileum) of the small intestine. The part of the intestine that is blocked off expands, which lessens its ability to absorb nutrients and pushl its contents through the digestive tract. There are four subtypes of jejunoileal atresia:
- Intestinal Atresia type I – A web-like membrane forms inside the intestine while the baby is forming in the uterus. The membrane blocks the intestine, but the intestine itself usually develops to a normal length.
- Intestinal Atresia type II – The dilated section of intestine forms a blind end. It is connected to a smaller segment of the intestine by scar tissue. The intestine develops to a normal length.
- Intestinal Atresia type III – Two blind ends of intestine are separated by a flaw in the intestinal blood supply. This significantly reduces the length of the intestine, which may result in long-term nutritional deficiencies or short gut syndrome.
- Intestinal Atresia type IV – Multiple sections of the intestine are blocked. This may result in a very short length of useful intestine.
- Infants with any of the four types of jejunoileal atresia usually vomit green bile within a day of their birth. However, those with obstructions farther down in the intestine may not vomit until two to three days later. A baby with jejunoileal atresia may develop a swollen belly, and not have a bowel movement during the first day of life the way most babies do.
- Colonic atresia – Less than 15% of babies with intestinal atresias experience this form. The bowel becomes massively dilated, and patients develop signs and symptoms similar to those associated with jejunoileal atresia. Colonic atresia may occur in conjunction with small bowel atresia, Hirschsprung's disease, or gastroschisis.
Intestinal Atresia and Stenosis Diagnosis
The methods used to diagnose intestinal atresia and stenosis vary depending on the type (or location) of the obstruction in the intestine. In newborns with the symptoms listed above, an abdominal X-ray is usually all that is needed to establish a diagnosis, sometimes accompanied by an X-ray contrast enema. More and more, intestinal obstructions are detected with prenatal ultrasonography. Using this imaging technique, doctors may find excess amniotic fluid, a sign that the intestine can not properly absorb the fluid. If excess amniotic fluid is found on an ultrasound, infant will be examined for intestinal atresia and stenosis after his or her birth using these methods: lower GI series, upper GI series, and abdominal ultrasound.
Because many newborns with intestinal atresia also have other life-threatening problems, echocardiography and other imaging studies of the heart and kidneys may also be performed after the infant is stabilized.
Intestinal Atresia and Stenosis Treatment
Children with intestinal atresia and stenosis need surgery to correct the problem. The type of operation they require depends on where the obstruction is located. Before the operation, a tube is placed into the stomach (through the mouth) to remove the excess fluid and gas. This prevents vomiting and aspiration, as well as providing babies with some relief from the discomfort caused by a swollen abdomen. Nutrients are provided intravenously, to replace what was lost through vomiting.
Babies with intestinal atresia feed through a tube that goes through their nasal passages directly into the stomach. This is left in place until their bowel function returns, a period of time which may vary from a few days to several weeks. Once the intestines can function normally, nutrition is given orally or through a feeding tube passed into the small intestine. During the period of bowel inactivity, nutrition is provided intravenously.
After the surgery, parents can expect their child's hospital stay to last from one to several weeks, until the child's diet is enough to provide a good level of nutrition. However, the hospital stay is often longer for premature infants.
Children will require continued regular follow-up to make sure they are growing and developing normally, and to ensure that their intestine is absorbing enough of the nutrients they need.
If a baby has a sufficient length of intestine, and there are no other associated problems, he or she generally does well after recovery. Complications after surgical therapy are rare, but may occur. During immediate postoperative and early recovery period, intestinal contents may leak at the suture line. This can cause an infection in the abdominal cavity and require additional surgery. Possible long-term complications include short gut syndrome, malabsorption syndromes, and segments of intestine that cannot function properly because they are dilated or paralyzed.
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