Makindo Medical Notes

Duodenal Atresia is a congenital malformation of the duodenum, usually presenting in neonates with early bilious vomiting. It is classically associated with the “double bubble” sign on abdominal X-ray and is one of the few neonatal surgical emergencies where outcome is excellent after prompt surgery.

About 🚼

• Definition: Congenital obstruction of the duodenum due to failure of recanalisation in fetal life.
• Onset: Presents in the neonatal period, often within hours of the first feed.
• Prognosis: Excellent with surgical correction; without surgery, it is uniformly fatal due to inability to establish enteral nutrition.

Aetiology & Associations 🧬

• Embryological defect: Failure of duodenal lumen to recanalise between weeks 8–10 of gestation.
• Genetic links: ~30–40% associated with Trisomy 21 (Down syndrome).
• Other syndromes: Can be part of VACTERL (vertebral, anal, cardiac, tracheoesophageal, renal, limb anomalies).
• Polyhydramnios: Common antenatal finding due to impaired fetal swallowing.
• Other anomalies: Cardiac defects (ASD, VSD) and renal tract malformations often coexist.

Epidemiology 📊

• Incidence: 1 in 6,000–10,000 live births worldwide.
• Sex ratio: ~1:1 (no clear male predominance).
• Most cases are sporadic (non-inherited).

Clinical Features 👶

• Vomiting: Bilious (green) vomiting within hours of birth (distal to ampulla of Vater).
• Abdominal distension: Especially upper abdomen due to duodenal dilatation.
• Electrolyte imbalance: Hypochloraemic metabolic alkalosis from loss of gastric acid.
• Failure to thrive: Dehydration, weight loss if diagnosis delayed.

Investigations 🔬

• Abdominal X-Ray: “Double bubble” sign – gas in stomach + proximal duodenum, no distal gas.
• Prenatal ultrasound: May reveal polyhydramnios and double bubble sign, allowing antenatal diagnosis.
• Contrast study: Considered if obstruction site uncertain.
• Echocardiogram: Screen for congenital heart disease (especially in Down syndrome).

Differential Diagnosis 🩺

• Pyloric stenosis: Later presentation, non-bilious vomiting, hypertrophied pylorus on ultrasound.
• Malrotation with volvulus: Bilious vomiting with acute abdominal compromise – surgical emergency.
• Jejunoileal atresia: Multiple dilated loops of bowel, not classic double bubble.
• Annular pancreas: Pancreatic tissue encircling duodenum causing obstruction.

Management 💉

• Antenatal planning: If diagnosed in utero → delivery at tertiary neonatal surgical centre.
• Initial stabilisation:
  • NG tube insertion for gastric decompression.
  • IV fluids + electrolyte correction (esp. hypochloraemia, hypokalaemia).
• Surgery: Standard = duodenoduodenostomy (end-to-side anastomosis). Sometimes duodenojejunostomy or bypass depending on anatomy.
• Post-op care:
  • Gradual reintroduction of feeds.
  • Parenteral nutrition until full enteral tolerance.
  • Monitor for leaks, strictures, delayed gastric emptying.

Prognosis 🌟

• Survival >95% in high-resource settings with early surgery.
• Outcomes depend on presence of associated anomalies (esp. congenital heart disease).

Classic Exam Pearls 📖

• Newborn with bilious vomiting + double bubble sign → duodenal atresia until proven otherwise.
• Association with Down syndrome is a high-yield exam fact.
• Polyhydramnios in antenatal scan → think duodenal obstruction.

References 📚

• NHS – Duodenal Atresia
• Merck Manual – Duodenal Atresia
• NORD – Duodenal Atresia