Intestinal Atresia

Intestinal atresia is a congenital anomaly in which there is a blockage of the intestine or bowel.  The intestine is categorized as small bowel which starts immediately after the stomach and the large bowel which starts immediately after the small bowel and ends as the rectum and anus. 

Intestinal atresia is a congenital anomaly in which there is a blockage of the intestine or bowel.  The intestine is categorized as small bowel which starts immediately after the stomach and the large bowel which starts immediately after the small bowel and ends as the rectum and anus. 

The small bowel is further divided into 3 parts: the duodenum which starts immediately after the stomach and then connects to the jejunum which then transitions into the ileum. The duodenum serves as the portion of the small bowel that mixes food, bile from the liver and digestive enzymes from the pancreas. The jejunum and ileum serve as the portion of the bowel where nutrients are absorbed into the body. The colon is the site where the bulk of water is absorbed in the intestinal tract. 

Duodenal atresia

Diagnosis

Duodenal atresia occurs in approximately 1 in 10,000 births and is usually diagnosed prenatally. on prenatal ultrasound there is a characteristic double bubble appearance as well as polyhydramnios or excess amniotic fluid.  Duodenal atresia is sometimes associated with Down’s syndrome or Trisomy 21 as well as cardiac abnormalities. When infants with duodenal atresia are born, they will have vomiting which may either be green (bilious) or clear (non-bilious). Patients with suspected duodenal atresia should have an abdominal x-ray to look for a double bubble signand also an echocardiogram to look for cardiac abnormalities. In addition, testing for trisomy 21 may also be appropriate. 

Classification

Duodenal atresia is classified depending on whether the blockage is before as pre-ampullary in which case the infant has non-bilious vomit or post-ampullary (bilious) in which case the vomit will be green.

Treatment

Treatment for duodenal atresia is surgical. The two ends of the duodenum are opened and sewn together. Care has to be taken to avoid injury to the ampulla of Vater where the bile duct drains into the duodenum. 

Outcomes

Outcomes are usually good with duodenal atresia. Often infants may stay in the intensive care nursery for several weeks to months while waiting for the intestines to return to normal function. We follow these patients long-term in our LIFE clinic. 

Jejuno-ileal atresia

Atresias of the jejunum and ileum are classified together.  They occur in approximately 1 in 10,000 births. Jejunoileal atresias may also occur in patients with other congenital anomalies such as gastroschisis, internal hernias, malrotation and meconium ileus, which is usually associated with cystic fibrosis. 

Diagnosis

Diagnosis may be made prenatally on ultrasound with the presence of dilated loops of bowel. Polyhydramnios is also often present. Infants with jejuno-ileal atresia will have green or bilious vomiting after birth. Xrays will show dilated loops of intestine. Contrast placed into the rectum after birth will show a narrow colon. This rules out other causes of intestinal blockage such as meconium plug, meconium ileus or Hirschsprung’s disease. 

Classification

Jejuno-ileal atresias are classified by the type of blockage in the intestinal tract. 

Type I consists of a membrane occluding the lumen of the intestine although the intestine has no visible gaps on the outside. 

Type II is a gap in the intestine with a fibrous remnant connecting the proximal and distal segments of intestine.

Type IIIA is a gap between the segments of the intestine as well as a gap in the mesentery.

Type IIIB is jejunal atresia usually due to blockage of the artery that goes to the small bowel, the superior mesenteric artery. The small bowel after the blockage has the appearance of a curled apple peel.  Often in these patients, there is a risk of inadequate small bowel potentially leading to small bowel syndrome.

Type IV consists of multiple atresias leading to the appearance of multiple sausage links. 

Treatment

Treatment is surgical. The ends of the small bowel are reconnected.  In more complicated cases such as type IIIB or IV multiple surgeries are required. 

Outcomes: Outcomes are dependent on the amount of bowel that is present.  

Colon or large bowel atresia

Colon and large bowel atresias are very rare with an incidence of approximately 1 in 40,000 births. Treatment is surgical either by creating a diverting ostomy and subsequently connecting the ends of the intestines at a later operation or by connecting the ends of the intestine at the first operation. Patients with colon atresia should also be worked up for Hirschsprung’s disease as they are high risk for Hirschsprung’s disease in addition to the colon atresia.