IBD Knowledge 4

Question 1

What is the significance of the 'string sign' seen on barium follow-through in Crohn's disease?

Accepted Answer

It represents severe luminal narrowing due to stricture or spasm

Answer

The string sign on barium studies indicates severe narrowing of the terminal ileum from stricture or intense spasm, a classic radiologic finding in Crohn's disease.

Question 2

Which of the following best describes the mechanism of corticosteroid resistance in IBD?

Accepted Answer

Overexpression of MDR1 p-glycoprotein effluxing steroids from cells

Answer

Overexpression of MDR1 (multidrug resistance gene 1) encodes p-glycoprotein, which pumps glucocorticoids out of target cells, reducing their anti-inflammatory effect.

Question 3

In UC, what does the term 'backwash ileitis' describe?

Accepted Answer

Inflammation of the terminal ileum due to reflux from a severely inflamed colon

Answer

Backwash ileitis occurs in ~17% of pancolitis UC patients when colonic contents and inflammation 'wash back' into the terminal ileum through an incompetent ileocecal valve.

Question 4

Which genetic variant in the NOD2 gene confers the highest risk for Crohn's disease?

Accepted Answer

NOD2 3020insC frameshift mutation

Answer

The NOD2 3020insC frameshift mutation (Leu1007fsinsC) produces a truncated, nonfunctional protein and is the variant most strongly associated with ileal Crohn's disease.

Question 5

What is 'pouchitis' and which IBD surgery predisposes patients to it?

Accepted Answer

Inflammation of the ileal pouch after IPAA surgery for UC

Answer

Pouchitis is inflammation of the ileal reservoir (J-pouch) created during IPAA surgery for UC, occurring in up to 50% of patients within 10 years.

IBD - Inflammatory Bowel Disease Practice Test

IBD - Inflammatory Bowel Disease Practice Test

IBD Knowledge 4