Duodenal diverticula

Epidemiology

• Relatively common - second most common site after colon
• Found on 1-5% of radiographic studies, and 9-23% of ERCPs, and 15-20% of autopsies

Risk factors

• Twice as common in women
• Rare in patients younger than 40

Pathophysiology

• Congenital vs acquired
• Extra-luminal vs intra-luminal
  • Extra-luminal - much more common, acquired, consist of mucosal or submucosal outpouchings herniated through a muscle defect in the bowel wall
    • Usually occur in D2 (62%), D3 (30%) or D4 (8%). D1 <1%.
    • Mostly on the medial wall (88%) when found in D2, around the ampulla
  • Intra-luminal - also known as 'windsock diverticula' - congenital - occur as a single saccular structure that is connected to the entire circumference or part of the wall of the duodenum, to create a duodenal web. Caused by incomplete recanalization of the duodenum during foetal development. Extremely rare.
• True vs false

Presentation

• Overwhelming majority are asymptomatic
• Usually noted incidentally on imaging
• Complications
  • Bleeding
    • Can be caused by inflammation, leading to erosion of a branch of SMA
  • Obstruction of the biliary and pancreatic ducts - can cause pancreatitis or cholangitis - Lemmel syndrome
    • Only seen in diverticula associated with ampulla of Vater
    • Ampulla usually enters the duodenum at the superior margin of the diverticulum, rather than through the diverticulum itself
    • Possibly caused by the diverticulum distorting the CBD as it enters the duodenum, resulting in partial obstruction and stasis
  • Blind loop syndrome (rare)
    • Stasis of intestinal contents -> overgrowth, malabsorption, steatorrhoea, megaloblastic anaemia
  • Iatrogenic injuries during procedures - haemorrhage or perforation
  • Non-specific epigastric complaints
    • Probably not related to the diverticulum

Investigation

• Endoscopy
  • Identified 75%, but more if a side-viewing scope is used
• AXR - atypical gas bubble
• CT
  • Large diverticula seen as a mass-like structure interposed between the duodenum and pancreatic head, containing air, air-fluid levels, fluid contrast material, or debris
• MRCP
  • Good for demonstrating the relationship between the diverticulum and the biliary and pancreatic ducts, and associated pathologic changes in the biliary system and pancreas
• CTA/99mTc-RBC scan - good for diagnosing haemorrhage

Management

• Asymptomatic diverticula should be left alone
• Symptomatic or complicated extra-luminal diverticula can be resected either endoscopically or via laparotomy and duodenotomy
• Intra-luminal diverticula generally require treatment regardless
  • Can be endoscopic or open
  • Even large diverticula >3cm or obstructing can be treated endoscopically, but haemorrhage or perforation generally means open is best

Diverticulectomy

• Can be done open or laparoscopic
• Wide Kocher manoeuvre to expose the duodenum
• Identify ampulla and protect
• Diverticulum excised (may need to do duodenotomy for diverticula embedded within the head of pancreas)
• Duodenum closed in a transverse or longitudinal fashion
• Omental patch can be used

Perforated diverticulum

• Excise diverticulum
• Close duodenum with a serosal patch from jejunal loop
• May be necessary to divert with a gastrojejunostomy or duodenojejunostomy if there is significant inflammation