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ABCRS practice questions

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Question 1Colon and Rectal Neoplasia

A 62-year-old man undergoes colonoscopy for screening and is found to have a single 6 mm sessile polyp in the sigmoid colon, which is removed by cold snare. What is the most appropriate surveillance interval?

  1. Repeat colonoscopy in 5 years Correct answer.
  2. Repeat colonoscopy in 3 years
  3. Repeat colonoscopy in 1 year
  4. Repeat colonoscopy in 10 years

Explanation

Low-risk findings (1-2 tubular adenomas under 10 mm) warrant surveillance at 5 years under current US guidance. A 10-year interval is reserved for average-risk screening with no adenomas. Shorter intervals apply to high-risk adenoma findings.

Question 2Colon and Rectal Neoplasia

Which histologic feature defines a sessile serrated lesion (sessile serrated adenoma/polyp) of the colon?

  1. Hyperplastic epithelium limited to the upper crypt
  2. Crypt distortion with basal dilation and horizontal growth at the crypt base Correct answer.
  3. Villous architecture with more than 75% villous component
  4. Dysplastic epithelium with pseudostratified nuclei

Explanation

Sessile serrated lesions are characterized by crypt architectural distortion, including basal crypt dilation, branching, and horizontal (boot-shaped) growth at the base. Hyperplastic polyps show proliferation limited to the upper crypt without basal distortion.

Question 3Colon and Rectal Neoplasia

A patient is diagnosed with a T1 rectal adenocarcinoma that has invaded the submucosa. Which feature on pathologic review most strongly predicts lymph node metastasis and would push toward radical resection rather than local excision?

  1. Absence of perineural invasion
  2. Tumor diameter of 1.5 cm
  3. Presence of lymphovascular invasion Correct answer.
  4. Well-differentiated histology

Explanation

Lymphovascular invasion is among the strongest predictors of nodal disease in T1 rectal cancer and is a high-risk feature favoring radical surgery. Depth of submucosal invasion, poor differentiation, and tumor budding are other high-risk features.

Question 4Colon and Rectal Neoplasia

Which germline mutation is associated with Lynch syndrome, and which cancer spectrum does it predispose to?

  1. STK11 mutation with hamartomatous polyps and perioral pigmentation
  2. BRAF V600E mutation with serrated polyposis
  3. Mismatch repair gene mutation with right-sided colon and endometrial cancer Correct answer.
  4. APC mutation with hundreds of colonic polyps

Explanation

Lynch syndrome results from germline mutations in mismatch repair genes (MLH1, MSH2, MSH6, PMS2, or EPCAM) and predisposes to early-onset right-sided colorectal cancer and endometrial cancer, among others. Tumors typically show microsatellite instability.

Question 5Colon and Rectal Neoplasia

A 45-year-old woman with a strong family history of colorectal cancer in a first-degree relative diagnosed at age 52 undergoes screening. When should she begin colonoscopy?

  1. At age 60, since her risk is only modestly elevated
  2. At age 50, like average-risk patients
  3. At age 45 with no adjustment for family history
  4. At age 40 or 10 years before the relative's diagnosis, whichever is earlier Correct answer.

Explanation

For a first-degree relative with colorectal cancer, screening begins at age 40 or 10 years before the youngest affected relative's diagnosis, whichever comes first. For a relative diagnosed at 52, this means starting at age 40.

Question 6Colon and Rectal Neoplasia

Which of the following is the most common site of distant metastasis from colorectal cancer?

  1. Liver Correct answer.
  2. Bone
  3. Brain
  4. Lung

Explanation

The liver is the most common site of hematogenous metastasis from colorectal cancer because venous drainage of the colon enters the portal circulation. Lung metastases occur but are less frequent at presentation.

Question 7Colon and Rectal Neoplasia

A 70-year-old man has a 2 cm rectal neuroendocrine tumor with invasion into the muscularis propria and no distant metastases. What is the most appropriate management?

  1. Radical resection with oncologic lymphadenectomy Correct answer.
  2. Observation with annual imaging
  3. Local excision with observation
  4. Endoscopic mucosal resection alone

Explanation

Rectal neuroendocrine tumors larger than 2 cm or with invasion beyond the submucosa carry substantial nodal metastatic risk and warrant radical oncologic resection. Small (<1 cm) lesions confined to the submucosa may be managed endoscopically.

Question 8Colon and Rectal Neoplasia

Which molecular pathway is most characteristic of the serrated neoplasia pathway leading to colorectal cancer?

  1. Mismatch repair gene deletion with intact BRAF
  2. APC inactivation followed by KRAS mutation and p53 loss
  3. BRAF mutation with CpG island methylation and microsatellite instability Correct answer.
  4. Beta-catenin nuclear accumulation without methylation

Explanation

The serrated pathway typically begins with BRAF V600E mutation and CpG island methylator phenotype, leading to MLH1 promoter methylation and microsatellite instability. This contrasts with the chromosomal instability (adenoma-carcinoma) pathway.

Question 9Colon and Rectal Neoplasia

A 55-year-old patient has a 1.2 cm pedunculated sigmoid polyp removed completely by snare polypectomy. Pathology shows tubular adenoma with clear margins. What is the recommended surveillance interval?

  1. 5 years
  2. 3 years Correct answer.
  3. 1 year
  4. 10 years

Explanation

An adenoma 10 mm or larger places the patient in the high-risk category, warranting surveillance at 3 years. Size at or above 10 mm is one of the defining high-risk criteria.

Question 10Colon and Rectal Neoplasia

Which of the following best describes the role of KRAS mutation testing in metastatic colorectal cancer?

  1. It predicts response to anti-EGFR antibodies
  2. It determines eligibility for immune checkpoint inhibitors
  3. It predicts resistance to anti-EGFR antibodies Correct answer.
  4. It predicts response to fluoropyrimidines

Explanation

KRAS (and NRAS) mutations are predictive of resistance to anti-EGFR monoclonal antibodies such as cetuximab and panitumumab, so testing guides therapy selection. Patients with mutated RAS do not benefit from these agents.

Question 11Colon and Rectal Neoplasia

A 68-year-old woman with a locally advanced rectal cancer (T3N1) is being planned for neoadjuvant therapy. What is the standard initial approach for locally advanced rectal cancer?

  1. Neoadjuvant chemotherapy alone without radiation
  2. Immediate surgery followed by adjuvant chemotherapy
  3. Neoadjuvant chemoradiation followed by surgery Correct answer.
  4. Surgery alone with no additional therapy

Explanation

Locally advanced rectal cancer (T3-4 or node-positive) is typically managed with neoadjuvant chemoradiation (or total neoadjuvant therapy) before surgery to reduce local recurrence. Surgery follows after restaging.

Question 12Colon and Rectal Neoplasia

A patient with colorectal cancer is found to have deficient mismatch repair (dMMR) on tumor testing. What is the significance of this finding?

  1. It indicates a poor prognosis and contraindicates immunotherapy
  2. It predicts response to immune checkpoint inhibitors Correct answer.
  3. It predicts resistance to fluoropyrimidines
  4. It rules out Lynch syndrome

Explanation

dMMR/MSI-high colorectal cancers are highly responsive to immune checkpoint inhibitors such as pembrolizumab, particularly in the metastatic setting. dMMR also prompts evaluation for Lynch syndrome.

Question 13Colon and Rectal Neoplasia

A 30-year-old man presents with rectal bleeding and is found to have hundreds of adenomatous polyps on colonoscopy. Which syndrome should be suspected?

  1. Juvenile polyposis syndrome
  2. Lynch syndrome
  3. Peutz-Jeghers syndrome
  4. Familial adenomatous polyposis Correct answer.

Explanation

Hundreds to thousands of adenomatous polyps in a young patient are characteristic of familial adenomatous polyposis, caused by germline APC mutation. Prophylactic colectomy is often required.

Question 14Colon and Rectal Neoplasia

Which is the most appropriate initial management for a 1 cm benign-appearing rectal carcinoid (neuroendocrine tumor) confined to the submucosa?

  1. Observation with no intervention
  2. Abdominoperineal resection
  3. Endoscopic resection Correct answer.
  4. Neoadjuvant chemoradiation

Explanation

Small (<1-2 cm) rectal neuroendocrine tumors confined to the submucosa without muscularis invasion or nodal disease can be managed with endoscopic resection. Larger or invasive lesions require more extensive surgery.

Question 15Colon and Rectal Neoplasia

A 72-year-old man has a large, laterally spreading sessile polyp in the cecum that cannot be removed en bloc. What is the most important reason to schedule early surveillance after piecemeal resection?

  1. High risk of incomplete resection and local recurrence Correct answer.
  2. Requirement to repeat biopsy for staging
  3. Need to assess for inflammatory bowel disease
  4. Risk of distant metastasis from residual polyp

Explanation

Piecemeal resection of large lesions carries a substantial risk of incomplete removal and local recurrence, so surveillance colonoscopy is typically performed at 3-6 months to detect and treat residual tissue.

Question 16Colon and Rectal Neoplasia

Which of the following is a recognized risk factor for colorectal cancer?

  1. Low red meat consumption
  2. High dietary fiber intake
  3. Regular physical activity
  4. Long-standing inflammatory bowel disease Correct answer.

Explanation

Long-standing extensive inflammatory bowel disease (especially ulcerative colitis) increases colorectal cancer risk through chronic inflammation and dysplasia. High fiber, physical activity, and low red meat intake are protective or neutral.

Question 17Colon and Rectal Neoplasia

In a patient with a T2N0 rectal cancer, what is the most appropriate surgical approach for curative intent?

  1. Wide local excision with radiation alone
  2. Endoscopic submucosal dissection
  3. Local excision with observation
  4. Total mesorectal excision Correct answer.

Explanation

T2 rectal cancer invades the muscularis propria and carries nodal risk, so total mesorectal excision with adequate margins is the standard curative approach. Local excision is generally reserved for selected T1 lesions.

Question 18Colon and Rectal Neoplasia

Which of the following best characterizes the recommended follow-up for a patient after curative resection of stage II colon cancer?

  1. History, physical, and CEA with periodic imaging Correct answer.
  2. Immediate adjuvant radiation to the colon
  3. No follow-up needed after surgery
  4. Annual colonoscopy only

Explanation

Post-resection surveillance for stage II colon cancer includes history and physical examination, CEA monitoring, and periodic imaging (often CT of chest, abdomen, and pelvis) for several years. Colonoscopy is also performed at intervals.

Question 19Colon and Rectal Neoplasia

A 58-year-old patient is found to have a flat, depressed lesion in the right colon with a Kudo pit pattern suggesting invasive cancer. What is the most appropriate next step?

  1. Cold snare polypectomy
  2. Endoscopic mucosal resection
  3. Observation in 1 year
  4. Surgical resection with oncologic margins Correct answer.

Explanation

Endoscopic features suggesting deep submucosal invasion (flat depressed morphology, abnormal pit pattern) warrant surgical resection because of the risk of nodal metastasis and incomplete endoscopic clearance.

Question 20Colon and Rectal Neoplasia

Which of the following statements about the adenoma-carcinoma sequence is correct?

  1. It involves direct transition from normal mucosa to carcinoma without precursor lesions
  2. It is driven primarily by BRAF mutation and CpG island methylation
  3. It typically requires inactivation of the APC tumor suppressor gene as an early event Correct answer.
  4. It is independent of chromosomal instability

Explanation

The classic adenoma-carcinoma sequence begins with APC inactivation, followed by KRAS mutation and later p53 loss, with chromosomal instability. This contrasts with the serrated pathway.

Question 21Colon and Rectal Neoplasia

A 40-year-old woman with a family history meeting Amsterdam criteria is being evaluated for Lynch syndrome. Which cancer screening is most important in addition to colonoscopy?

  1. Endometrial cancer screening and consideration of risk-reducing hysterectomy Correct answer.
  2. Annual mammography starting at age 25
  3. Routine brain MRI
  4. Annual chest CT for lung cancer

Explanation

Women with Lynch syndrome have a markedly elevated risk of endometrial cancer, so endometrial surveillance and discussion of risk-reducing hysterectomy are recommended in addition to colonoscopy.

Question 22Colon and Rectal Neoplasia

Which of the following is the most appropriate treatment for a patient with a completely obstructing left-sided colon cancer and a stable clinical condition?

  1. Chemotherapy alone without surgery
  2. Immediate primary anastomosis without decompression
  3. Staged resection or stenting followed by resection Correct answer.
  4. Observation with serial imaging

Explanation

Obstructing left-sided colon cancer is often managed with decompression (stent) or staged resection to allow bowel preparation and avoid high-risk primary anastomosis in the unprepared bowel.

Question 23Colon and Rectal Neoplasia

Which of the following best describes the purpose of the Bethesda guidelines?

  1. To classify serrated polyps
  2. To stage colorectal cancer
  3. To determine surveillance intervals after polypectomy
  4. To identify patients who should undergo testing for Lynch syndrome Correct answer.

Explanation

The Bethesda guidelines identify patients whose colorectal tumors should be tested for microsatellite instability or mismatch repair deficiency to screen for Lynch syndrome. They guide who should undergo further genetic evaluation.

Question 24Colon and Rectal Neoplasia

A patient with a 3 cm villous adenoma of the rectum is found to have high-grade dysplasia but no invasive cancer on biopsy. What is the most appropriate management?

  1. Radiation therapy alone
  2. Observation with annual biopsy
  3. Endoscopic resection or local excision with close surveillance Correct answer.
  4. Immediate abdominoperineal resection

Explanation

Villous adenomas with high-grade dysplasia but no invasive cancer can be managed with complete endoscopic or local excision and close surveillance, provided clear margins are achieved. Radical surgery is reserved for invasive cancer.

Question 25Colon and Rectal Neoplasia

Which of the following is a recognized complication of total mesorectal excision for rectal cancer?

  1. Anterior resection syndrome Correct answer.
  2. Peptic ulcer disease
  3. Hyperthyroidism
  4. Nephrolithiasis

Explanation

Anterior resection syndrome, characterized by frequency, urgency, and incontinence after sphincter-preserving rectal surgery, is a well-recognized functional complication of total mesorectal excision.

Question 26Colon and Rectal Neoplasia

A 62-year-old man undergoes screening colonoscopy and is found to have a 2.5 cm sessile polyp in the ascending colon. Biopsy shows a tubular adenoma with high-grade dysplasia. What is the most appropriate next step in management?

  1. Repeat colonoscopy in 1 year
  2. Endoscopic mucosal resection or piecemeal polypectomy Correct answer.
  3. Surgical resection of the right colon
  4. Refer for genetic testing for familial adenomatous polyposis

Explanation

Large sessile polyps with high-grade dysplasia but no invasive cancer can often be managed endoscopically with advanced resection techniques such as endoscopic mucosal resection (EMR) or piecemeal polypectomy, followed by close surveillance. Surgery is reserved for lesions that cannot be completely resected endoscopically or those with invasive cancer.

Question 27Colon and Rectal Neoplasia

Which of the following is the most common histological type of colorectal cancer?

  1. Adenocarcinoma Correct answer.
  2. Mucinous adenocarcinoma
  3. Neuroendocrine tumor
  4. Squamous cell carcinoma

Explanation

Adenocarcinoma accounts for approximately 90-95% of colorectal cancers. Mucinous, signet-ring, squamous, and neuroendocrine tumors are less common variants.

Question 28Colon and Rectal Neoplasia

A 55-year-old woman undergoes colonoscopy for rectal bleeding and is found to have a 2 cm rectal lesion. Biopsy shows a well-differentiated neuroendocrine tumor (carcinoid) with invasion into the submucosa but not the muscularis propria. There is no evidence of metastasis. What is the most appropriate management?

  1. Low anterior resection
  2. Abdominoperineal resection
  3. Endoscopic resection with surveillance
  4. Local excision with clear margins Correct answer.

Explanation

Rectal neuroendocrine tumors that are 1-2 cm in size and invade the submucosa but not the muscularis propria have a low risk of metastasis and can be treated with local excision achieving clear margins. Endoscopic resection may be inadequate for tumors >1 cm or with deeper invasion.

Question 29Colon and Rectal Neoplasia

Which of the following best describes the recommended surveillance interval after curative resection of stage II colon cancer?

  1. Colonoscopy at 5 years, then every 10 years if normal
  2. Colonoscopy at 3 years, then every 5 years if normal
  3. Colonoscopy at 1 year, then every 3 years if normal Correct answer.
  4. No further colonoscopy unless symptoms develop

Explanation

After curative resection for stage II or III colorectal cancer, guidelines recommend a colonoscopy at 1 year to detect metachronous lesions. If this is normal, the next colonoscopy is typically in 3 years, and then every 5 years.

Question 30Colon and Rectal Neoplasia

A 45-year-old man undergoes colonoscopy for screening and is found to have a 1.5 cm sessile polyp in the sigmoid colon. The polyp is removed by snare polypectomy. Pathology reveals a tubular adenoma with low-grade dysplasia and negative margins. What is the recommended follow-up interval?

  1. Repeat colonoscopy in 3 years Correct answer.
  2. Repeat colonoscopy in 10 years
  3. Repeat colonoscopy in 5 years
  4. Repeat colonoscopy in 1 year

Explanation

For a patient with a 1.5 cm adenoma (advanced adenoma, defined as ≥1 cm), the recommended surveillance interval is 3 years after complete removal. This is based on an increased risk of metachronous advanced neoplasia.

Question 31Colon and Rectal Neoplasia

Which of the following is a recognized hereditary syndrome associated with the development of hundreds to thousands of colorectal adenomas?

  1. Juvenile polyposis syndrome
  2. Familial adenomatous polyposis Correct answer.
  3. Lynch syndrome
  4. Peutz-Jeghers syndrome

Explanation

Familial adenomatous polyposis (FAP) is characterized by the development of hundreds to thousands of adenomatous polyps in the colon and rectum, typically beginning in adolescence. It is caused by germline mutations in the APC gene.

Question 32Colon and Rectal Neoplasia

A 60-year-old woman is diagnosed with a T3N0 rectal cancer located 5 cm from the anal verge. She undergoes neoadjuvant chemoradiation followed by total mesorectal excision (TME). Which of the following is the most important factor in determining the need for adjuvant chemotherapy?

  1. The presence of lymphovascular invasion
  2. The pathologic stage of the resected specimen Correct answer.
  3. The patient's age
  4. The distance of the tumor from the anal verge

Explanation

After neoadjuvant therapy and surgery for rectal cancer, adjuvant chemotherapy decisions are primarily guided by the pathologic stage (ypT and ypN) of the resected specimen. Patients with residual nodal involvement or higher yp stage are more likely to benefit from adjuvant chemotherapy.

Question 33Colon and Rectal Neoplasia

Which of the following best describes the role of microsatellite instability (MSI) testing in colorectal cancer?

  1. It is used to screen for familial adenomatous polyposis
  2. It identifies patients with Lynch syndrome and predicts response to immunotherapy Correct answer.
  3. It determines the need for neoadjuvant chemoradiation in rectal cancer
  4. It predicts response to anti-EGFR therapy

Explanation

MSI testing is used to screen for Lynch syndrome (via mismatch repair deficiency) and also has predictive value: high MSI (MSI-H) tumors are more likely to respond to immune checkpoint inhibitors. It does not predict anti-EGFR response or guide neoadjuvant therapy in rectal cancer.

Question 34Colon and Rectal Neoplasia

A 70-year-old man presents with a large, obstructing sigmoid colon cancer. He is hemodynamically stable and has no evidence of perforation. What is the most appropriate initial management?

  1. Placement of a self-expanding metallic stent as a bridge to surgery Correct answer.
  2. Immediate primary resection with anastomosis
  3. Creation of a diverting colostomy
  4. Neoadjuvant chemotherapy followed by surgery

Explanation

For left-sided obstructing colon cancer in a stable patient, a self-expanding metallic stent can be used as a bridge to surgery, allowing for optimization and a one-stage resection. This approach reduces the need for emergency surgery and stoma formation.

Question 35Colon and Rectal Neoplasia

Which of the following is the most appropriate treatment for a patient with a 4 cm villous adenoma of the rectum with high-grade dysplasia and no evidence of invasive cancer on biopsy?

  1. Endoscopic piecemeal resection
  2. Local excision with clear margins Correct answer.
  3. Observation with repeat biopsy in 6 months
  4. Abdominoperineal resection

Explanation

A large villous adenoma with high-grade dysplasia but no invasive cancer can be treated with local excision to achieve clear margins. This preserves the rectum while adequately treating the benign but premalignant lesion.

Question 36Colon and Rectal Neoplasia

Which of the following is a recognized complication of total mesorectal excision (TME) for rectal cancer?

  1. Small bowel obstruction
  2. Ureteral injury
  3. Sexual dysfunction Correct answer.
  4. Fecal incontinence

Explanation

Sexual dysfunction (erectile dysfunction and ejaculatory problems in men, dyspareunia in women) is a well-recognized complication of TME due to injury to the pelvic autonomic nerves. Fecal incontinence can occur but is less specific; ureteral injury and small bowel obstruction are possible but not the most characteristic complications.

Question 37Colon and Rectal Neoplasia

A 35-year-old woman is diagnosed with colon cancer. Her father had colon cancer at age 45, and her paternal aunt had endometrial cancer at age 50. Which of the following is the most appropriate next step in genetic evaluation?

  1. Test the tumor for mismatch repair deficiency or microsatellite instability Correct answer.
  2. Reassure the patient that this is likely sporadic
  3. Recommend colonoscopy every 10 years
  4. Perform germline testing for APC mutations

Explanation

The family history of early-onset colon cancer and endometrial cancer suggests Lynch syndrome. Guidelines recommend tumor testing for mismatch repair deficiency (dMMR) or microsatellite instability (MSI) as the initial step, followed by germline testing if positive.

Question 38Colon and Rectal Neoplasia

A 50-year-old man undergoes colonoscopy and is found to have a flat, depressed lesion in the right colon. Chromoendoscopy reveals a Kudo pit pattern type V. Biopsy confirms intramucosal carcinoma. What is the most appropriate management?

  1. Argon plasma coagulation
  2. Surveillance colonoscopy in 6 months
  3. Surgical resection Correct answer.
  4. Endoscopic mucosal resection

Explanation

A flat, depressed lesion with a Kudo type V pit pattern and confirmed intramucosal carcinoma has a high risk of submucosal invasion and lymph node metastasis. Surgical resection is recommended because endoscopic resection may be inadequate for cure.

Question 39Colon and Rectal Neoplasia

A 65-year-old woman with a history of stage II colon cancer treated with surgery alone 3 years ago presents with a rising CEA level. CT scan of the chest, abdomen, and pelvis is unremarkable. What is the most appropriate next step?

  1. Repeat CEA in 3 months
  2. Colonoscopy
  3. PET-CT scan Correct answer.
  4. Initiate chemotherapy

Explanation

A rising CEA with negative conventional imaging warrants further evaluation with PET-CT to detect occult recurrence or metastasis. PET-CT can identify lesions not seen on CT and guide further management.

Question 40Colon and Rectal Neoplasia

A 58-year-old man undergoes colonoscopy and is found to have a single 6 mm tubular adenoma in the transverse colon, which is completely removed. He has no family history of colorectal cancer and no other risk factors. According to current U.S. Multi-Society Task Force guidance, when should his next surveillance colonoscopy be performed?

  1. In 3 years
  2. In 5 years
  3. In 10 years Correct answer.
  4. In 1 year

Explanation

Patients with one or two small (<10 mm) tubular adenomas with low-grade dysplasia are considered low risk, and current U.S. Multi-Society Task Force guidance recommends returning to routine screening intervals, typically 10 years, rather than intensive surveillance. Surveillance intervals shorten as polyp number, size, or histology becomes more advanced.

Question 41Inflammatory Bowel Disease

Which cytokine pathway is the primary target of ustekinumab in the treatment of Crohn's disease?

  1. Tumor necrosis factor alpha
  2. The interleukin-6 receptor
  3. Alpha-4-beta-7 integrin
  4. The p40 subunit shared by interleukin-12 and interleukin-23 Correct answer.

Explanation

Ustekinumab is a monoclonal antibody directed against the p40 subunit common to IL-12 and IL-23, blocking signaling through both cytokines. Anti-TNF agents target TNF alpha, while vedolizumab targets the alpha-4-beta-7 integrin. Tocilizumab targets the IL-6 receptor.

Question 42Inflammatory Bowel Disease

A 28-year-old with ulcerative colitis has had symptoms for 10 days with six bloody stools per day, hemoglobin 10.5 g/dL, and CRP of 45 mg/L. Which classification best fits this presentation?

  1. Mild proctitis
  2. Irritable bowel syndrome overlap
  3. Chronic quiescent colitis
  4. Acute severe ulcerative colitis Correct answer.

Explanation

Acute severe ulcerative colitis is defined by six or more bloody stools per day plus systemic toxicity markers such as anemia or elevated inflammatory markers. Tenesmus and urgency are common but the stool frequency and inflammatory burden drive the classification. Quiescent disease describes patients without active symptoms.

Question 43Inflammatory Bowel Disease

Which finding on colonoscopy is most characteristic of Crohn's disease rather than ulcerative colitis?

  1. Continuous mucosal inflammation extending proximally from the rectum
  2. Loss of haustral markings throughout the colon
  3. Skip lesions with intervening normal mucosa Correct answer.
  4. Diffuse granularity confined to the rectum

Explanation

Crohn's disease is characterized by discontinuous, transmural inflammation with skip lesions and rectal sparing. Ulcerative colitis produces continuous, circumferential mucosal disease beginning in the rectum. Loss of haustra and diffuse granularity reflect chronic UC.

Question 44Inflammatory Bowel Disease

Which extraintestinal manifestation of IBD most closely parallels the activity of the underlying bowel disease?

  1. Ankylosing spondylitis
  2. Primary sclerosing cholangitis
  3. Pyoderma gangrenosum
  4. Peripheral arthritis of the large-joint type Correct answer.

Explanation

Peripheral arthritis in IBD generally fluctuates with bowel disease activity and often improves when the intestinal inflammation is controlled. Pyoderma gangrenosum, axial arthropathy, and primary sclerosing cholangitis typically follow an independent course.

Question 45Inflammatory Bowel Disease

A patient with moderate ulcerative colitis has failed conventional therapy and is being started on tofacitinib. Which monitoring is most important before and during treatment?

  1. Serial liver biopsy
  2. Lipid panel and assessment for latent tuberculosis and viral hepatitis Correct answer.
  3. Routine electrocardiography
  4. Serum ceruloplasmin

Explanation

Tofacitinib, a JAK inhibitor, requires screening for latent tuberculosis and hepatitis B, along with baseline and follow-up lipid panels because dyslipidemia is a recognized effect. Live vaccines should be avoided during therapy. Routine liver biopsy, ECG, and ceruloplasmin are not part of standard monitoring.

Question 46Inflammatory Bowel Disease

Which laboratory pattern is most consistent with iron deficiency anemia in a patient with active IBD?

  1. High ferritin with normal transferrin saturation
  2. Low ferritin with low transferrin saturation Correct answer.
  3. High ferritin with low transferrin saturation
  4. Normal ferritin with high transferrin saturation

Explanation

Iron deficiency anemia produces low ferritin and low transferrin saturation because iron stores are depleted. Ferritin is an acute-phase reactant and may be falsely normal or elevated during active inflammation, so transferrin saturation is helpful in that setting. High ferritin with low saturation suggests anemia of chronic disease.

Question 47Inflammatory Bowel Disease

Which vaccine is contraindicated in a patient receiving high-dose corticosteroids for an IBD flare?

  1. Hepatitis B vaccine
  2. Pneumococcal conjugate vaccine
  3. Live attenuated zoster vaccine Correct answer.
  4. Inactivated influenza vaccine

Explanation

Live attenuated vaccines are contraindicated during significant immunosuppression because of the risk of vaccine-strain infection. Inactivated vaccines such as influenza, pneumococcal, and hepatitis B are safe and recommended. The recombinant zoster vaccine is preferred over the live formulation in immunosuppressed patients.

Question 48Inflammatory Bowel Disease

Which stool test is most useful for distinguishing active inflammatory diarrhea from irritable bowel syndrome?

  1. Fecal calprotectin Correct answer.
  2. Clostridium difficile toxin
  3. Fecal occult blood
  4. Stool culture

Explanation

Fecal calprotectin is a neutrophil-derived protein that rises with intestinal inflammation and reliably distinguishes inflammatory from functional diarrhea. Stool culture and C. difficile toxin identify specific infections, and occult blood is less sensitive for grading inflammation.

Question 49Inflammatory Bowel Disease

A patient with Crohn's disease develops a perianal fistula. Which imaging modality is best for defining fistula anatomy and detecting abscesses?

  1. Plain abdominal radiography
  2. Transabdominal ultrasound
  3. Barium enema
  4. Pelvic MRI Correct answer.

Explanation

Pelvic MRI provides detailed delineation of fistula tracts and identifies abscesses, making it the preferred modality for perianal Crohn's disease. Plain films and barium enema lack soft-tissue detail, and transabdominal ultrasound is limited in the pelvis.

Question 50Inflammatory Bowel Disease

Which medication is most appropriate for inducing remission in mild-to-moderate ulcerative colitis limited to the rectum?

  1. Oral prednisone
  2. Topical mesalamine suppository Correct answer.
  3. Infliximab
  4. Azathioprine monotherapy

Explanation

Topical mesalamine delivered as a suppository is first-line therapy for proctitis because it achieves high local drug concentrations with minimal systemic exposure. Oral steroids and biologics are reserved for more extensive or refractory disease. Azathioprine is not used for induction.