What is the most likely cause of jejunoileal atresia in a neonate?

Etiology of Jejunoileal Atresia in Neonates

The most likely cause of jejunoileal atresia in a neonate is an intrauterine mesenteric vascular accident. This vascular event leads to ischemia and subsequent necrosis of the affected bowel segment during fetal development, resulting in the formation of an atretic segment.

Clinical Presentation and Diagnosis

Jejunoileal atresia typically presents with:

• Bilious vomiting within the first 2 days of life due to proximal intestinal obstruction 1
• Abdominal distension from accumulation of fluid and gas proximal to the obstruction 1
• Failure to pass meconium, which is characteristic of distal bowel obstruction 1

Diagnostic imaging findings include:

• Abdominal radiographs showing multiple air-fluid levels and distended small bowel loops, which are characteristic of intestinal obstruction 1
• In cases of jejunal atresia, a "triple bubble" sign may be visible on radiographs 1
• Contrast enema is the diagnostic imaging procedure of choice for suspected distal obstruction, which can demonstrate a microcolon due to lack of contents moving through the bowel 1

Pathophysiology of Jejunoileal Atresia

Jejunoileal atresia results from:

• An intrauterine mesenteric vascular accident that causes ischemia and necrosis of the affected bowel segment 2, 3
• This vascular compromise typically occurs after the intestine has formed, rather than during early embryologic development 4
• The compromised blood supply leads to resorption of the affected bowel segment, resulting in complete obstruction 5

Distinguishing Features from Other Causes

Jejunoileal atresia must be differentiated from other causes of neonatal intestinal obstruction:

• Abnormal rotation of midgut (malrotation) - typically presents with bilious vomiting but is caused by abnormal intestinal rotation during embryologic development rather than a vascular accident 1
• Failure of recanalization of primitive gut lumen - this is the mechanism for duodenal atresia, not jejunoileal atresia 1
• Neural crest migration failure - this is associated with Hirschsprung disease, not jejunoileal atresia 1
• Persistence of cloacal membrane - this is associated with anorectal malformations, not jejunoileal atresia 1

Management and Prognosis

Management of jejunoileal atresia involves:

• Prompt surgical intervention with resection of the atretic segment and primary anastomosis when possible 4, 5
• In type IIIB (apple-peel) atresia, more extensive bowel involvement may be present, increasing the risk for short bowel syndrome 2
• Postoperative care in a neonatal intensive care unit with close monitoring for complications 3

Prognosis considerations:

• Overall mortality rate is approximately 4%, with most deaths related to associated anomalies or postoperative complications 4
• Long-term gastrointestinal quality of life is generally good for isolated jejunoileal atresia 4
• Concomitant gastrointestinal anomalies are associated with impaired outcomes 4
• Unlike duodenal atresia, jejunoileal atresia is less commonly associated with other congenital anomalies 6

Important Clinical Considerations

• Early diagnosis and surgical intervention are crucial to prevent complications such as perforation, sepsis, and death 3
• Prenatal diagnosis via ultrasound is possible but may be missed, as occurred in several reported cases 3
• Postoperative complications include anastomotic leak, bowel obstruction, and infection 4