Intestinal Atresia and Stenosis

Intestinal Atresia/Stenosis - Embryo's Oopsie Daisy

• Definitions:
  • Atresia: Complete congenital obstruction of intestinal lumen; a gap.
  • Stenosis: Incomplete obstruction or narrowing of intestinal lumen.
• Incidence: Affects ~1 in 1500-5000 live births.
• General Embryological Basis:
  • Failure of recanalization: Fetal gut's solid cord stage (Weeks 8-10) fails to re-open.
  • Vascular accidents: Intrauterine ischemic events cause bowel segment resorption.

⭐ Intestinal atresia is the most common cause of congenital intestinal obstruction in newborns.

Duodenal Atresia - Double Bubble Classic

• Embryology: Failure of recanalization of duodenum (typically 8th-10th week gestation).
• Clinical Features:
  • Bilious vomiting (85%) within hours of birth.
  • Epigastric fullness/distension.
  • Polyhydramnios in utero (50%).
• Associations:
  • Down syndrome (Trisomy 21) (~30%).
  • 📌 VACTERL (Vertebral, Anal, Cardiac, Tracheo-Esophageal, Renal, Limb defects).
  • Annular pancreas, malrotation.
• Diagnosis:
  • X-ray: Classic "double bubble" sign (stomach and proximal duodenum).
  • Absence of distal gas (indicates complete obstruction).

⭐ Approximately 30% of infants with duodenal atresia have Down syndrome (Trisomy 21).

Jejunoileal & Colonic Atresia - Vascular Event Aftermath

• Etiology: In-utero mesenteric vascular accident (ischemic insult) → bowel necrosis & resorption.

  ⭐ Jejunoileal atresias are most commonly caused by an in-utero mesenteric vascular accident.

• Jejunoileal (JI) Atresia Classification (Louw & Barnard):

  Type	Description
  I	Membranous web
  II	Fibrous cord between blind ends
  IIIa	Mesenteric gap, V-shaped
  IIIb	Apple-peel/Christmas tree deformity
  IV	Multiple atresias (string of sausages)

• Clinical: Bilious vomiting (first 24-48h), abdominal distension, failure to pass meconium.
• Diagnosis:
  • X-ray: Multiple air-fluid levels, no distal gas.
  • Contrast enema: Microcolon; rules out colonic atresia/meconium ileus.
• Colonic Atresia: Rarer; similar etiology; types (membranous, cord, separation).

Diagnosis & Management - Spot & Snip Strategy

• Antenatal Diagnosis: Ultrasound showing polyhydramnios.

  ⭐ Polyhydramnios is a significant antenatal indicator, especially for proximal intestinal atresias like duodenal atresia.

• Postnatal Diagnosis:
  • Plain abdominal X-ray (e.g., "double bubble" sign).
  • Upper GI contrast study if needed; contrast enema for distal obstruction.
• Preoperative Stabilization: NPO, nasogastric/orogastric tube decompression, IV fluids, electrolyte correction, prophylactic antibiotics.
• Surgical Principles:
  • Resection of dilated proximal bowel, primary end-to-end anastomosis.
  • Tapering enteroplasty for significant caliber discrepancy.
  • Stoma creation if primary anastomosis is unsafe.
• Postoperative Complications: Anastomotic leak, stricture formation, short bowel syndrome.

High‑Yield Points - ⚡ Biggest Takeaways

• Duodenal atresia is strongly associated with Down syndrome and presents with a classic "double bubble" sign on X-ray.
• Jejunoileal atresias typically result from in-utero vascular accidents or ischemic insults.
• The "apple peel" or "Christmas tree" deformity is characteristic of Type IIIb jejunal atresia.
• Bilious vomiting shortly after birth is a cardinal sign of intestinal obstruction distal to the ampulla of Vater.
• Maternal polyhydramnios is a common antenatal finding, especially with proximal intestinal atresias.
• Intestinal stenosis causes incomplete obstruction, often presenting with more subtle or delayed symptoms than atresia.
• Definitive management for all intestinal atresias and symptomatic stenosis is surgical repair.