Jejunal atresia is a birth defect in a newborn characterized by partial or complete absence of the membrane connecting the small intestines to the abdominal wall (the mesentery). It causes a portion of the small intestines (the jejunum) to twist around an artery that supplies blood to the colon (the marginal artery). This leads to an intestinal blockage or "atresia." Common symptoms in the newborn include feeding difficulties, failure to thrive, vomiting bile (a yellowish-green fluid), abdominal swelling, and/or absence of bowel movements after birth. 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 in some cases. Jejunal atresia is typically treated with surgery.

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.

Because jejunal atresia rarely occurs in more than one family member, there may be a genetic component or predisposition in some cases.

Most cases of jejunal atresia occur sporadically in people with no family history of the condition. However, it can rarely affect more than one family member. In these families, jejunal atresia is likely due to a genetic cause and appears to be inherited in an autosomal recessive or multifactorial manner.

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.

Jejunal atresia is typically treated with surgery as soon as possible. Total parenteral nutrition (TPN) is generally necessary for a period of time following surgery until normal meals are tolerated.

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.