Atresia of small intestine

Synonyms

11

Overview

It is a rare genetic disorder and defects of the small intestine include both atresia and stenosis. Atresia involves closure or disconnection of a portion or multiple portions of the small intestine while stenosis is a narrowing, webbing, or incomplete closure of a portion of the small intestine. Patients with this disorder are born with a partial absence of the fold of the stomach membrane that connects the small intestine to the back wall of the abdomen  (the mesentery). As a result, one of the three portions of the small intestine (the jejunal) twists around one of the arteries of the colon called the marginal artery and causes a blockage (atresia). It is sometimes compared to an apple peel in appearance.

Symptoms

• Constipation
• Failure to thrive 

Causes

It typically occurs sporadically in people with no family history of the condition; however, more than one family member can rarely be affected, suggesting that there may be a genetic component predisposition in some cases. The disease may be inherited as an autosomal recessive trait, or it may occur sporadically with no known cause.

The most common cause of non-duodenal intestinal atresia is a vascular accident in utero that leads to decreased intestinal perfusion and ischemia of the respective segment of bowel. This leads to narrowing, or in the most severe cases, complete obliterat.

Jejunal atresia occurs when the membrane that attaches the small intestines to the abdominal wall (called the mesentery) is partially or completely absent. As a result, a portion of the small intestines (the jejunum) twists around an artery that supplies blood to the colon (the marginal artery). This leads to an intestinal blockage or "atresia."

Scientists suspect that it may be a consequence of disruption of blood flow in the developing fetus, leading to the death of cells and tissue in the affected area (necrosis). There may be various reasons that blood flow becomes disrupted.

Diagnosis

Intestinal atresias are often discovered before birth: either during a routine sonogram which shows a dilated intestinal segment due to the blockage, or by the development of polyhydramnios (the build up of too much amniotic fluid in the uterus). 

In some cases, it may be diagnosed before birth on a prenatal ultrasound or fetal MRI. This is helpful because infants can be treated promptly after birth, reducing the risk of complications. Ultrasound findings that may suggest intestinal atresia include dilated loops of bowel, hyperechoic bowel (it appears brighter than it should), and accumulation of fluid (ascites). Because prenatal ultrasound is not always accurate, X-rays and imaging studies with contrast should be obtained after birth to confirm the diagnosis.

After birth, a diagnosis is often suspected based on the presence of characteristic signs and symptoms, which suggest intestinal obstruction. These may include abdominal distension, vomiting bile, and failure to pass stool. Imaging studies can then be ordered to confirm the diagnosis.

Prognosis

The long-term outlook (prognosis) for people with intestinal atresia is usually good, and in general, children do well post-operatively. Overall survival rates (including preterm babies) have reached 90%, with a surgical mortality of less than 1%. Most of the mortality occurs in infants with medical conditions such as prematurity or respiratory distress syndrome, associated anomalies, and complications related to short bowel syndrome.

Treatment

Fetal and neonatal intestinal atresia treated with using laparotomy after birth. If the area affected is small, the surgeon may be able to remove the damaged portion and join the intestine back together. Total parenteral nutrition (TPN) is generally necessary for a period of time following surgery until normal meals are tolerated.

Resources

• NIH