Duodenal Atresia

Intrinsic causes (within the duodenum)

These are the most common after duodenal atresia.

1. Duodenal Stenosis

• Partial obstruction rather than complete
• Mild Polyhydramnios may be milder
• May present later

2. Duodenal Web

• Thin mucosal membrane obstructing lumen
• Can produce a “windsock deformity” postnatally

3. Annular Pancreas

• Pancreatic tissue encircles the duodenum
• Often associated with Duodenal Atresia

4. Malrotation with Midgut Volvulus

• May show double bubble plus:
  • Dilated proximal bowel
  • Abnormal SMA/SMV relationship

5. Ladd Bands

• Fibrous bands compressing the duodenum

6. Preduodenal Portal Vein

• Often associated with Heterotaxy Syndrome

7. Enteric Duplication Cyst (duodenal duplication)

• Can appear as cyst near second part of duodenum

Functional or transient causes

8. Megaduodenum

• Functional dilatation

9. Transient duodenal dilatation

• Seen occasionally in early gestation
• May resolve on follow-up

Mimics of double bubble

10. Choledochal Cyst

• Usually separate from stomach

11. Cystic Biliary Atresia

12. Pancreatic Cyst

Associations

• Trisomy 21 (25–40%)
• Congenital Heart Defects (especially AV canal)
• Malrotation
• Esophageal Atresia
• VACTERL Association
• Heterotaxy Syndrome

Classic features of Duodenal Atresia

• Double bubble sign
• Dilated stomach
• Dilated proximal duodenum
• No distal bowel dilatation
• Progressive polyhydramnios
• Usually detected after 24 weeks

Feature	Suggests
Persistent double bubble	True obstruction
Distal bowel seen	Stenosis/web rather than atresia
Separate cystic structure	Duplication cyst / biliary cyst
Changing bowel pattern	Malrotation/volvulus

Genetic association

• Trisomy 21 - ~25–40% risk