INFLAMMATORY BOWEL DISEASE (IBD) EXAM
QUESTIONS AND CORRECT ANSWERS (VERIFIED
ANSWERS) PLUS RATIONALES 2026
Questions 1–15: Definitions, Epidemiology, and Classification
Question 1
What is the fundamental difference between Crohn's disease (CD) and ulcerative
colitis (UC)?
A. CD affects only the colon; UC affects the small bowel
B. CD is a transmural, granulomatous inflammation that can affect any part of
the GI tract (skip lesions); UC is a continuous, mucosal inflammation limited to
the colon and rectum
C. CD is infectious; UC is autoimmune
D. UC is more common in males
Rationale: Crohn's disease is characterised by transmural (full-thickness)
inflammation, skip lesions, and can affect any part of the GI tract (mouth to anus).
Ulcerative colitis is a continuous mucosal (not transmural) inflammation starting
at the rectum and extending proximally (limited to the colon).
Question 2
What is the approximate prevalence of IBD in Western countries?
A. 1 in 10,000
B. 1 in 1,000
C. 1 in 200-400 (0.25-0.5%)
D. 1 in 20
,*Rationale: IBD prevalence in Western populations (Europe, North America) is
approximately 0.3-0.5% (1 in 200-400). Crohn's disease and ulcerative colitis have
similar prevalence. Incidence is increasing in newly industrialised countries.*
Question 3
What is the age distribution of IBD?
A. Only elderly
B. Bimodal: peak at 15-30 years (second decade), second smaller peak at 50-70
years
C. Only children
D. Uniform across all ages
*Rationale: IBD most commonly presents in young adults (age 15-30). A second,
smaller peak occurs in older adults (50-70 years). Some patients present in
childhood (5-10%).*
Question 4
What is the male-to-female ratio in ulcerative colitis?
A. 2:1 male predominance
B. 1:1 (equal)
C. 2:1 female predominance
D. 5:1 male
*Rationale: UC has an equal gender distribution. Crohn's disease has a slight
female predominance (1.2-1.5:1).*
Question 5
Which of the following is a known environmental risk factor for IBD?
A. Appendectomy (protective for UC)
B. Smoking (risk factor for Crohn's disease; protective for UC)
C. Western diet (high fat, low fibre)
D. All of the above
,Rationale: Smoking increases risk of Crohn's disease but is protective against
ulcerative colitis. Appendectomy before age 20 is protective against UC (not CD).
Western diet (high saturated fat, low fibre, processed foods) increases IBD risk.
Question 6
What is the most common extra-intestinal manifestation of IBD?
A. Primary sclerosing cholangitis (PSC)
B. Peripheral arthritis (type 1 – pauciarticular, associated with disease activity)
C. Erythema nodosum
D. Uveitis
*Rationale: Arthritis is the most common extra-intestinal manifestation, affecting
up to 30% of IBD patients. Type 1 (pauciarticular, <5 joints, asymmetrical, lower
limbs) is associated with disease activity and improves with treatment of IBD.*
Question 7
Which of the following is associated with ulcerative colitis but NOT with Crohn's
disease?
A. Fistulas
B. Primary sclerosing cholangitis (PSC)
C. Perianal disease
D. Granulomas on histology
*Rationale: PSC is strongly associated with UC (70-80% of PSC patients have UC). It
is rare in CD (<10%). Fistulas, perianal disease, and granulomas are more
characteristic of Crohn's disease.*
Question 8
What is the lifetime risk of colorectal cancer in patients with extensive ulcerative
colitis (pancolitis) after 30 years of disease?
A. 1%
B. 5%
C. 10%
D. 15-30% (in historical cohorts, lower with modern surveillance and treatment)
, *Rationale: Risk of colorectal cancer is increased in long-standing UC (and Crohn's
colitis). After 30 years of pancolitis, the cumulative risk is 15-30% (though modern
surveillance and mesalazine may reduce risk).*
Question 9
What is the classification of ulcerative colitis by extent?
A. Ileal, colonic, perianal
B. Proctitis (E1), left-sided (E2, up to splenic flexure), extensive (E3, proximal to
splenic flexure), pancolitis (E4)
C. Mild, moderate, severe
D. Inflammatory, fibrostenotic, penetrating
*Rationale: The Montreal classification for UC: E1 – ulcerative proctitis (limited to
rectum), E2 – left-sided (up to splenic flexure), E3 – extensive (proximal to splenic
flexure), E4 – pancolitis.*
Question 10
What is the classification of Crohn's disease by behaviour (Montreal
classification)?
A. Proctitis, left-sided, extensive
B. B1 – non-stricturing, non-penetrating (inflammatory); B2 – stricturing; B3 –
penetrating (fistulising); p – perianal disease modifier
C. Mild, moderate, severe
D. Active, remission
Rationale: The Montreal classification for CD behaviour: B1 (inflammatory), B2
(stricturing – luminal narrowing, obstructive symptoms), B3 (penetrating – fistulas,
abscesses). Perianal disease is added as 'p'.
Question 11
What is the approximate proportion of Crohn's disease patients who develop
perianal fistulas?
A. 5%
B. 10%
QUESTIONS AND CORRECT ANSWERS (VERIFIED
ANSWERS) PLUS RATIONALES 2026
Questions 1–15: Definitions, Epidemiology, and Classification
Question 1
What is the fundamental difference between Crohn's disease (CD) and ulcerative
colitis (UC)?
A. CD affects only the colon; UC affects the small bowel
B. CD is a transmural, granulomatous inflammation that can affect any part of
the GI tract (skip lesions); UC is a continuous, mucosal inflammation limited to
the colon and rectum
C. CD is infectious; UC is autoimmune
D. UC is more common in males
Rationale: Crohn's disease is characterised by transmural (full-thickness)
inflammation, skip lesions, and can affect any part of the GI tract (mouth to anus).
Ulcerative colitis is a continuous mucosal (not transmural) inflammation starting
at the rectum and extending proximally (limited to the colon).
Question 2
What is the approximate prevalence of IBD in Western countries?
A. 1 in 10,000
B. 1 in 1,000
C. 1 in 200-400 (0.25-0.5%)
D. 1 in 20
,*Rationale: IBD prevalence in Western populations (Europe, North America) is
approximately 0.3-0.5% (1 in 200-400). Crohn's disease and ulcerative colitis have
similar prevalence. Incidence is increasing in newly industrialised countries.*
Question 3
What is the age distribution of IBD?
A. Only elderly
B. Bimodal: peak at 15-30 years (second decade), second smaller peak at 50-70
years
C. Only children
D. Uniform across all ages
*Rationale: IBD most commonly presents in young adults (age 15-30). A second,
smaller peak occurs in older adults (50-70 years). Some patients present in
childhood (5-10%).*
Question 4
What is the male-to-female ratio in ulcerative colitis?
A. 2:1 male predominance
B. 1:1 (equal)
C. 2:1 female predominance
D. 5:1 male
*Rationale: UC has an equal gender distribution. Crohn's disease has a slight
female predominance (1.2-1.5:1).*
Question 5
Which of the following is a known environmental risk factor for IBD?
A. Appendectomy (protective for UC)
B. Smoking (risk factor for Crohn's disease; protective for UC)
C. Western diet (high fat, low fibre)
D. All of the above
,Rationale: Smoking increases risk of Crohn's disease but is protective against
ulcerative colitis. Appendectomy before age 20 is protective against UC (not CD).
Western diet (high saturated fat, low fibre, processed foods) increases IBD risk.
Question 6
What is the most common extra-intestinal manifestation of IBD?
A. Primary sclerosing cholangitis (PSC)
B. Peripheral arthritis (type 1 – pauciarticular, associated with disease activity)
C. Erythema nodosum
D. Uveitis
*Rationale: Arthritis is the most common extra-intestinal manifestation, affecting
up to 30% of IBD patients. Type 1 (pauciarticular, <5 joints, asymmetrical, lower
limbs) is associated with disease activity and improves with treatment of IBD.*
Question 7
Which of the following is associated with ulcerative colitis but NOT with Crohn's
disease?
A. Fistulas
B. Primary sclerosing cholangitis (PSC)
C. Perianal disease
D. Granulomas on histology
*Rationale: PSC is strongly associated with UC (70-80% of PSC patients have UC). It
is rare in CD (<10%). Fistulas, perianal disease, and granulomas are more
characteristic of Crohn's disease.*
Question 8
What is the lifetime risk of colorectal cancer in patients with extensive ulcerative
colitis (pancolitis) after 30 years of disease?
A. 1%
B. 5%
C. 10%
D. 15-30% (in historical cohorts, lower with modern surveillance and treatment)
, *Rationale: Risk of colorectal cancer is increased in long-standing UC (and Crohn's
colitis). After 30 years of pancolitis, the cumulative risk is 15-30% (though modern
surveillance and mesalazine may reduce risk).*
Question 9
What is the classification of ulcerative colitis by extent?
A. Ileal, colonic, perianal
B. Proctitis (E1), left-sided (E2, up to splenic flexure), extensive (E3, proximal to
splenic flexure), pancolitis (E4)
C. Mild, moderate, severe
D. Inflammatory, fibrostenotic, penetrating
*Rationale: The Montreal classification for UC: E1 – ulcerative proctitis (limited to
rectum), E2 – left-sided (up to splenic flexure), E3 – extensive (proximal to splenic
flexure), E4 – pancolitis.*
Question 10
What is the classification of Crohn's disease by behaviour (Montreal
classification)?
A. Proctitis, left-sided, extensive
B. B1 – non-stricturing, non-penetrating (inflammatory); B2 – stricturing; B3 –
penetrating (fistulising); p – perianal disease modifier
C. Mild, moderate, severe
D. Active, remission
Rationale: The Montreal classification for CD behaviour: B1 (inflammatory), B2
(stricturing – luminal narrowing, obstructive symptoms), B3 (penetrating – fistulas,
abscesses). Perianal disease is added as 'p'.
Question 11
What is the approximate proportion of Crohn's disease patients who develop
perianal fistulas?
A. 5%
B. 10%
