NBME 22 Answers : Block 1 : #29 = A 28-year-old man comes to the emergency department ...

nbme22/Block 1/Question#29

A 28-year-old man comes to the emergency department ...

Jejunum

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submitted by usmleuser007(84),

Intussusception is generally caused by a blockage in the GI tract caused by a tumor, polyp, diverticulum, or just immobility at part of the tract.

1) My thought was that the patient had a Meckel diverticulum yes it happens in 2 feet from the ileocecal valve; but that is in about %2 of the population

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submitted by mcl(167),

These images are useful in combination.

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submitted by iviax94(5),

CT shows mass on the left side of his abdomen and you’re told it’s intussusception. Asks which part of the GI tract is most likely to cause the pain. I immediately looked for ileocecal junction ... not an answer choice. Why is the answer jejunum (vs. duodenum)?

liverdietrying The picture is key here. You’re right that ileocecal is most common, but ileo-ileal and jejuno-jejunal are the next most common (I think I might just know this from having done clerkships already, not sure). Ileo-ileal isn’t an answer, so that rules that out. Look at where the arrows are pointing in the picture as well. Its on the L, ruling out appendix and cecum. And the slice is not at the level of the duodenum, ruling out that answer. So by process of elimination based on the picture you could get this one too. +2

dr.xx Duodeno-duodenal intussusception is a rare because of the retroperitoneal fixation of the duodenum. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4529645/ +1

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submitted by lnsetick(28),

How are you able to tell that the CT slice is not at the level of duodenum?

zelderonmorningstar I think the small intestine narrows as you go along, so jejunum would most likely intuss into the duodenum. +

yotsubato Duodenum is fixed to the retroperitoneal wall, and also has lots of named vessels attached to it, along with the pancreaticobiliary duct and ampulla. It cant really intussuscept. +

gh889 You should also know that the duodenum is almost purely on the right side of the body +3

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submitted by wolvarien(0),

I have answered this question with this method the CT is showing a mass on the left appendix is on the right so this choice is wrong Ceacum is on the right so this choice is wrong stomach is on the middle so this choice is wrong duodenum intussusception never heard of it so the only thing left is Jejunum

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submitted by hello(49),

Please help - how are you able to tell that the CT image is not at the level of duodenum?

I don't know what I'm looking for to compare and contrast a CT at the level of the duodenum vs the CT given in this Q.