IBD Knowledge 3 — Questions and Answers
Question 1: Which IBD medication requires testing for TPMT enzyme activity before initiation?
- Infliximab
- Azathioprine (Correct answer)
- Mesalamine
- Budesonide
Correct answer: Azathioprine
TPMT (thiopurine methyltransferase) deficiency increases the risk of severe myelosuppression with azathioprine and 6-mercaptopurine, so testing is required before use.
Question 2: What is the primary indication for performing a proctocolectomy with ileal pouch-anal anastomosis (IPAA) in UC?
- Mild UC unresponsive to mesalamine
- Medically refractory UC or dysplasia/cancer (Correct answer)
- Perianal Crohn's disease
- Clostridium difficile superinfection
Correct answer: Medically refractory UC or dysplasia/cancer
IPAA (J-pouch surgery) is the curative procedure for UC, indicated in medically refractory disease, high-grade dysplasia, or colorectal cancer.
Question 3: Fistula-in-ano associated with Crohn's disease is best initially evaluated by which imaging modality?
- CT scan of abdomen
- MRI of the pelvis (Correct answer)
- Transabdominal ultrasound
- Plain abdominal X-ray
Correct answer: MRI of the pelvis
MRI pelvis is the gold standard for evaluating perianal fistulas in Crohn's disease because it provides superior soft tissue delineation without radiation.
Question 4: Which cytokine is the primary therapeutic target of ustekinumab?
- TNF-alpha
- IL-6
- IL-12 and IL-23 (shared p40 subunit) (Correct answer)
- IL-17A
Correct answer: IL-12 and IL-23 (shared p40 subunit)
Ustekinumab targets the shared p40 subunit of IL-12 and IL-23, blocking both cytokines involved in Th1 and Th17 inflammatory pathways.
Question 5: What is the recommended interval for surveillance colonoscopy in a patient who has had extensive UC for 8 years?
- Every 5 years
- Every 1-2 years (Correct answer)
- Every 10 years
- No surveillance needed
Correct answer: Every 1-2 years
After 8-10 years of extensive UC, annual or biennial surveillance colonoscopy is recommended due to significantly elevated colorectal cancer risk.
Question 6: Which of the following is a known trigger for flares in IBD patients?
- Regular aerobic exercise
- NSAIDs such as ibuprofen (Correct answer)
- High-fiber diet
- Adequate sleep
Correct answer: NSAIDs such as ibuprofen
NSAIDs can disrupt intestinal mucosal integrity and inhibit prostaglandin synthesis, precipitating or worsening IBD flares.
Question 7: Primary sclerosing cholangitis (PSC) is most frequently associated with which IBD phenotype?
- Crohn's ileitis
- Crohn's colitis
- Ulcerative colitis (pancolitis) (Correct answer)
- Microscopic colitis
Correct answer: Ulcerative colitis (pancolitis)
PSC occurs in approximately 2-7% of UC patients, with the strongest association seen in those with extensive or pancolitis phenotype.
IBD Knowledge 3
Which IBD medication requires testing for TPMT enzyme activity before initiation?