Why does Hirschsprung present with bilious vomiting?

[studylol]

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Hello friends,

Question in title. It affects the colon so I am not seeing why this condition might lead to bilious vomiting.

Thanks!

 

[RLSGrasshopper]

The bile duct joins the pancreatic duct & attaches to the first portion of the duodenum at the Ampulla of Vater (which can be constricted with opiates - another pathology worry here). Hirschprung effects the large colon. So when the patient vomits, bile is able to project backwards; hence, bilous vomit. However, the is not true for Hypertrophic Pyloric Sphincter (Olive Sign) given that the pylorus comes before the biliary tract, and there would be no bile projecting back into the stomach. Anatomy is key here. http://www.mumbaicancer.com/images/bile-duct1.jpg

Key facts about Hirschsprung Disease
- Rectum is always involved, so no stool in present in the rectum
- no meconium first 48 hrs
- bilous vomiting
- necrotizing enterocolits
- contains constrictions
- Biopsy the "Narrow" Submucosa portion because that's were the neural crest cells failed to migrate
- associated with Down Syndrome
- results in Toxic Megacolon (Ddx: Chaga's Disease & Ulcerative Colitis)

 

[pathologyDO]

As stated above, if the colon is blocked there is one way to go... Back up. Since bile is secreted proximal to the block, patients will have billious vomit