What are the causes of duodenal obstruction?

Causes of Duodenal Obstruction

Duodenal obstruction results from intrinsic or extrinsic mechanisms, with duodenal atresia being the most common intrinsic cause in neonates, while malrotation with midgut volvulus, annular pancreas, and duodenal webs represent other critical etiologies that require urgent recognition. 1

Intrinsic Causes

Congenital Anomalies

• Duodenal atresia is the most common cause of congenital duodenal obstruction, accounting for the majority of cases presenting with the classic "double bubble" sign on radiography 1, 2
• Duodenal stenosis represents a partial obstruction that may present later than complete atresia 2, 3
• Duodenal web is a rare intrinsic cause that creates a membranous obstruction within the duodenal lumen 1
• Duplication cysts can cause obstructing lesions within the duodenal wall 1

Acquired Intrinsic Lesions

• Crohn's disease can manifest as duodenal obstruction through stricture formation, stenotic areas, or inflammatory changes, though this is an unusual presentation 4
• Primary duodenal adenocarcinoma can cause malignant stricture, particularly in the distal duodenum (D3-D4), representing a rare but significant cause in adults 5
• Peptic ulcer disease with chronic scarring can lead to duodenal stenosis, requiring surgical intervention in complicated cases 3

Extrinsic Causes

Vascular and Anatomic Compression

• Malrotation with midgut volvulus is a surgical emergency that must be excluded urgently in any neonate with bilious vomiting, as 20% of infants with bilious vomiting in the first 72 hours have midgut volvulus 1
• Annular pancreas represents pancreatic tissue encircling the duodenum, causing external compression 6
• Superior mesenteric artery (SMA) syndrome causes compression of the third portion of the duodenum between the SMA and aorta, typically managed conservatively 5
• Internal hernia can cause duodenal obstruction, particularly in post-bariatric surgery patients 1

Malignant Extrinsic Compression

• Metastatic disease or adjacent organ malignancies (such as caecal carcinoma) can invade retroperitoneal structures and compress D3-D4 5
• Carcinomatosis peritoneal can cause extrinsic compression of the duodenum 7

Post-Surgical Causes

• Adhesive disease following abdominal surgery can cause duodenal obstruction, though this is less common than small bowel obstruction from adhesions 7
• Jejuno-jejunostomy stenosis or kinking after Roux-en-Y gastric bypass can present with features of duodenal obstruction 1

Critical Diagnostic Considerations

Neonatal Presentation

• Bilious vomiting within the first 2 days of life with the "double bubble" sign and no distal gas indicates duodenal atresia in 91% of cases (32 of 35 patients in one series) 1
• However, malrotation with volvulus must be excluded as it accounted for 2 of 35 cases with double bubble sign and requires emergency surgery 1
• About 15% of proximal bowel obstructions present with nonbilious vomiting, which can delay diagnosis 1

Adult Presentation

• Distal duodenal obstruction (D3-D4) presents with gastric outlet obstruction symptoms plus bilious vomiting, requiring endoscopic or radiological confirmation of post-bulbar obstruction 5
• Upper GI series is the gold standard for diagnosing malrotation/midgut volvulus with 96% sensitivity 8
• CT imaging is essential for identifying transition points, masses, and extrinsic compression in adult patients 5

Common Pitfalls to Avoid

• Never assume a double bubble sign is always benign duodenal atresia—malrotation with volvulus can present identically and requires immediate surgical intervention 1
• In young females with duodenal obstruction, consider ovarian masses, endometriosis, or pelvic inflammatory disease as potential causes 9
• Duodenal strictures in inflammatory bowel disease require endoscopic biopsies to exclude malignancy before proceeding with medical or endoscopic management 9
• Late complications occur in 12% of patients after repair of congenital duodenal anomalies, with 6% late mortality, necessitating long-term follow-up into adulthood 3