USMLE Step 3 Quiz
Practice Inflammatory Bowel Disease Longitudinal Care in USMLE Step 3 with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.
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A 35-year-old woman with a known history of left-sided ulcerative colitis, maintained on high-dose oral mesalamine, presents to her primary care physician with a 3-week history of increased stool frequency (from 2 to 6 per day), urgency, and intermittent bloody stools. She is hemodynamically stable and her C-reactive protein is 15 mg/L (normal <5 mg/L).
Which of the following is the most appropriate next step in her outpatient management?
This quiz focuses on Inflammatory Bowel Disease Longitudinal Care, giving you a quick way to practice the rules, question types, and explanations that matter most for USMLE Step 3.
Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.
A 35-year-old woman with a known history of left-sided ulcerative colitis, maintained on high-dose oral mesalamine, presents to her primary care physician with a 3-week history of increased stool frequency (from 2 to 6 per day), urgency, and intermittent bloody stools. She is hemodynamically stable and her C-reactive protein is 15 mg/L (normal <5 mg/L).
Which of the following is the most appropriate next step in her outpatient management?
Explanation: When you encounter a patient with known ulcerative colitis presenting with worsening symptoms, you need to assess disease severity and choose appropriate step-up therapy. This patient shows clear signs of a mild-to-moderate flare: increased stool frequency, urgency, bloody stools, and elevated inflammatory markers, but remains hemodynamically stable. The correct approach is adding oral prednisone (D). Since her current mesalamine therapy isn't controlling the flare, you need to escalate to corticosteroids. Oral prednisone is appropriate for mild-to-moderate flares in hemodynamically stable outpatients. A 4-week course allows sufficient time for induction of remission while minimizing long-term steroid exposure. Option A is incorrect because broad-spectrum antibiotics aren't indicated for UC flares unless there's clear evidence of superimposed infection, which isn't suggested here. Option B simply increasing mesalamine dose is insufficient since she's already on high-dose therapy and experiencing breakthrough symptoms - this represents treatment failure requiring escalation. Option C recommends inpatient IV corticosteroids, but this patient doesn't meet criteria for severe colitis (she's hemodynamically stable with moderate symptoms), making outpatient oral therapy appropriate. The key distinction is recognizing mild-moderate versus severe UC flares. Severe flares require hospitalization and IV steroids, while mild-moderate flares can be managed outpatient with oral corticosteroids. Watch for hemodynamic stability, frequency of bloody stools, and overall clinical picture to guide this decision. Remember the step-wise approach: mesalamine → oral steroids → IV steroids/immunosuppressants.
A 34-year-old man with fistulizing Crohn disease has been receiving infliximab infusions every 8 weeks for 18 months with good effect. Two weeks after his most recent infusion, he develops symmetric polyarthritis of his hands and knees and a faint malar rash. He denies fever. Laboratory studies show a newly positive antinuclear antibody (ANA) and anti-double-stranded DNA (anti-dsDNA) antibodies.
Which of the following is the most likely diagnosis?
Explanation: The clinical presentation of arthritis, malar rash, and new-onset positive ANA and anti-dsDNA antibodies in a patient treated with an anti-TNF agent like infliximab is characteristic of drug-induced lupus erythematosus. While serum sickness-like reactions can occur, they are less likely to be associated with the specific seroconversion to anti-dsDNA. Crohn's-associated arthritis is typically seronegative. New-onset rheumatoid arthritis is less likely given the temporal relationship to the drug and the specific autoantibody profile.
A 42-year-old man with a 15-year history of ulcerative colitis involving the entire colon is seen for a routine follow-up appointment. He has been in clinical remission on oral mesalamine for the past 5 years. A surveillance colonoscopy performed 3 years ago showed quiescent colitis with no evidence of dysplasia.
According to current guidelines, what is the most appropriate recommendation for this patient's next colorectal cancer surveillance?
Explanation: Patients with long-standing (≥8 years) extensive ulcerative colitis are at high risk for colorectal cancer. Surveillance colonoscopy is recommended every 1 to 2 years for patients with pancolitis. The risk is determined by the duration and extent of disease, not solely by current inflammatory activity. Fecal immunochemical testing is not an adequate surveillance method for IBD-associated cancer risk. A 5-year interval is too long for a high-risk patient with pancolitis.
A 45-year-old postmenopausal woman with a 20-year history of Crohn disease involving the terminal ileum is seen for follow-up. Her disease has been managed with three courses of prednisone in the past two years, each lasting 6-8 weeks. She is currently in clinical remission on adalimumab. She has no personal history of fractures.
Which of the following is the most appropriate screening for this patient at this time?
Explanation: This patient has multiple risk factors for osteoporosis, including inflammatory bowel disease itself (a risk factor for malabsorption and chronic inflammation), postmenopausal status, and a history of significant corticosteroid use (≥3 months cumulative in the past). Therefore, she meets the criteria for osteoporosis screening with a DEXA scan. While monitoring vitamin D and calcium is important, it is not a screening test for bone mineral density. The risk from steroids is cumulative. Plain radiographs are insensitive for detecting early bone loss.
A 29-year-old woman who is 10 weeks pregnant presents for follow-up of her ulcerative colitis. Her disease has been in deep remission for over a year on maintenance therapy with oral sulfasalazine. She expresses concern about the medication's effect on her pregnancy and asks if she should discontinue it.
Which of the following is the most appropriate advice regarding her medication?
Explanation: When managing inflammatory bowel disease during pregnancy, you must balance maternal disease control with fetal safety. Active IBD poses greater risks to both mother and fetus than most maintenance medications, making continued treatment crucial. Sulfasalazine is considered safe during pregnancy and is classified as FDA Pregnancy Category B. The drug has been used extensively in pregnant women with IBD and rheumatoid arthritis without increased teratogenic risk. However, sulfasalazine does have one important mechanism of action that requires attention: it inhibits folate absorption and metabolism. Since adequate folate is essential for preventing neural tube defects, especially during the first trimester, folic acid supplementation (typically 5mg daily) should be added when continuing sulfasalazine during pregnancy. Option A is incorrect because reducing the dose risks losing disease control without providing additional safety benefits. Option B is dangerous because discontinuing effective maintenance therapy significantly increases the risk of disease flare, which poses substantial risks including preterm labor, low birth weight, and maternal complications. Option C represents unnecessary switching since sulfasalazine is already safe in pregnancy, and topical mesalamine may be less effective for maintaining systemic disease control. Remember for USMLE Step 3: IBD management during pregnancy prioritizes maintaining remission over medication concerns. Most IBD maintenance medications (sulfasalazine, mesalamine, certain immunosuppressants) are safer than active disease. Always consider adding folic acid when sulfasalazine is used in pregnancy due to folate interference.
A 40-year-old woman with a long-standing history of Crohn disease, currently managed with mesalamine, presents with a 2-week history of multiple tender, erythematous nodules on her anterior shins. She also reports increased abdominal cramping and diarrhea. She denies joint pain or eye symptoms.
Which of the following is the most appropriate next step in the management of her skin condition?
Explanation: The patient's skin lesions are characteristic of erythema nodosum, an extraintestinal manifestation of IBD. The activity of erythema nodosum typically parallels the activity of the underlying bowel disease. Her worsening gastrointestinal symptoms suggest a flare of her Crohn disease. The primary treatment for erythema nodosum in this context is to treat the underlying IBD flare, which typically involves initiating systemic corticosteroids. NSAIDs can exacerbate IBD and should be avoided. A skin biopsy is not usually necessary for classic lesions. Topical steroids are ineffective.
A 32-year-old man with Crohn disease has been in sustained deep remission for 2 years on combination therapy with infliximab and azathioprine. He has had no symptoms, his C-reactive protein and fecal calprotectin levels are normal, and a recent colonoscopy showed complete mucosal healing. He is concerned about the long-term risks of immunosuppression and wishes to simplify his regimen.
What is the most appropriate recommendation for de-escalating his therapy?
Explanation: In patients with IBD on combination therapy with a biologic and an immunomodulator who are in deep, sustained remission, de-escalation can be considered. Evidence suggests that discontinuing the immunomodulator (azathioprine) while continuing the biologic (infliximab) maintains remission rates better than the reverse and reduces the risk of infections and non-melanoma skin cancer associated with long-term thiopurine use. Discontinuing the biologic carries a high risk of relapse. Stopping both medications would likely lead to a flare.
A 50-year-old man with a 20-year history of ulcerative colitis presents for routine follow-up. He is asymptomatic. His laboratory results are notable for an alkaline phosphatase of 450 U/L (normal 40-120 U/L). An MRCP is performed and confirms a diagnosis of primary sclerosing cholangitis (PSC). His most recent colonoscopy one year ago was normal.
In addition to his routine IBD care, which of the following surveillance strategies is now indicated?
Explanation: When you encounter a patient with both inflammatory bowel disease (IBD) and primary sclerosing cholangitis (PSC), you need to understand that this combination dramatically increases colorectal cancer risk. PSC occurs in about 5% of ulcerative colitis patients, but when present, it creates a synergistic effect that accelerates malignant transformation in the colon. The correct answer is D because patients with UC and concurrent PSC require annual colonoscopy with random biopsies throughout the colon, even when asymptomatic. The random biopsies are crucial because dysplasia in PSC patients can be flat and invisible to standard endoscopy. This intensive surveillance should begin immediately upon PSC diagnosis, regardless of UC duration or current disease activity. Option A is dangerous because quiescent colitis doesn't eliminate cancer risk - in fact, PSC patients can develop colorectal cancer even with inactive IBD. Option B reflects outdated practice; ERCP with brushings was once used for cholangiocarcinoma surveillance but has been largely abandoned due to poor sensitivity and procedure-related risks. Option C addresses the wrong organ system - while PSC patients do have increased hepatobiliary malignancy risk, gallbladder polyp surveillance isn't the established standard. Remember this key association: IBD + PSC = immediate upgrade to annual colonoscopy with random biopsies. This is one of the highest-risk scenarios for colorectal cancer in gastroenterology, requiring the most aggressive surveillance protocol regardless of symptom status or previous normal examinations.
A 26-year-old man with a known history of Crohn disease presents with persistent, non-painful drainage from a site near his anus. On examination, there is a single external opening 4 cm from the anal verge with a palpable cord-like tract. An MRI of the pelvis confirms a complex, high transsphincteric fistula. He is currently only taking mesalamine.
Which of the following is the most appropriate long-term medical therapy for this condition?
Explanation: Complex perianal fistulas are a serious complication of Crohn disease and require aggressive medical management to promote healing and prevent complications. Anti-TNF agents (e.g., infliximab, adalimumab) are the cornerstone of therapy for fistulizing Crohn disease and have been shown to induce and maintain fistula closure. Antibiotics can be used as an adjunct or for associated abscesses but are not effective as long-term monotherapy for fistula healing. Surgical fistulotomy carries a high risk of incontinence with a high (transsphincteric) fistula. Budesonide has minimal systemic effect and is not effective for fistulizing disease.
A 39-year-old woman with ileocolonic Crohn disease has persistent fatigue. Her hemoglobin is 9.8 g/dL and MCV is 75 fL. Her ferritin is 10 ng/mL (normal >30 ng/mL) and transferrin saturation is 8% (normal 20-50%). She has been taking oral ferrous sulfate for 3 months without improvement in her anemia or symptoms. Her fecal calprotectin is 650 mcg/g (normal <50 mcg/g).
Which of the following is the most appropriate next step in management?
Explanation: When you encounter iron deficiency anemia in inflammatory bowel disease patients, you need to distinguish between simple iron deficiency and iron deficiency secondary to active inflammation. The key is recognizing that untreated inflammation prevents effective iron absorption and utilization, making iron supplementation futile until the underlying disease is controlled. This patient has classic iron deficiency anemia (low hemoglobin, low MCV, low ferritin, low transferrin saturation) but the critical clue is her markedly elevated fecal calprotectin of 650 mcg/g. Calprotectin is a biomarker of intestinal inflammation - normal levels are under 50 mcg/g, and her level indicates severely active Crohn disease. The failure to respond to 3 months of oral iron therapy despite appropriate supplementation confirms that active inflammation is blocking iron absorption and utilization through hepcidin-mediated mechanisms. Option D is correct because controlling the underlying Crohn disease inflammation is essential before iron therapy can be effective. Without treating the active disease, any form of iron supplementation will likely fail. Option A (IV iron) might seem logical since oral iron failed, but IV iron won't work effectively while severe inflammation persists. Option B (transfusion) isn't indicated - her hemoglobin of 9.8 g/dL, while low, doesn't meet transfusion thresholds in a stable patient. Option C (higher oral iron dose) ignores that absorption is impaired due to inflammation, not inadequate dosing. Remember: In IBD patients with refractory iron deficiency anemia, always check inflammatory markers. Treat the inflammation first, then reassess iron status.
A 28-year-old man with moderate-to-severe Crohn disease experienced a primary non-response to a 12-week induction course of adalimumab, an anti-TNF agent. Therapeutic drug monitoring confirmed adequate drug levels and no anti-drug antibodies. He continues to have active symptoms and endoscopic evidence of severe inflammation.
Which of the following medications would be the most appropriate next choice for this patient?
Explanation: This patient has demonstrated a primary non-response to an anti-TNF agent with adequate drug levels, suggesting that the TNF pathway is not the optimal therapeutic target for his disease. In this situation, switching to a biologic with a different mechanism of action is recommended. Ustekinumab, which targets interleukins 12 and 23, is an effective and appropriate choice. Switching to another anti-TNF agent (infliximab, certolizumab) is less likely to be effective in a primary non-responder. Methotrexate is an immunomodulator and would not be potent enough for this patient who has already failed a first-line biologic.
A 19-year-old college student is diagnosed with moderate Crohn disease of the ileum. You recommend initiating treatment with a biologic agent. The patient is hesitant, stating, "I read online that these drugs can cause cancer and serious infections. I'd rather just deal with the symptoms than take those risks."
Which of the following is the most appropriate initial response?
Explanation: The best approach involves shared decision-making. This begins with validating the patient's concerns, which are based on real, though often small, risks. The next crucial step is to provide balanced information, contrasting the risks of the medication with the significant risks of inadequately treated Crohn disease, including bowel damage, malnutrition, fistulas, abscesses, and the need for surgery. Dismissing their concerns (B) is counterproductive. Prescribing an ineffective therapy like a 5-ASA for moderate disease (C) is inappropriate. Surgical referral (D) is premature before medical options are fully explored and discussed.
A 45-year-old man with moderate-to-severe ulcerative colitis was started on ustekinumab (an IL-12/23 inhibitor) 16 weeks ago after failing anti-TNF therapy. He reports that his symptoms of diarrhea and urgency have improved by about 50%, but he still has 4-5 bowel movements per day with some blood. His C-reactive protein has decreased but remains mildly elevated.
Which of the following is the most appropriate next step to guide further management?
Explanation: This patient has had a partial clinical response to ustekinumab. The next step is to objectively assess for endoscopic improvement (mucosal healing), which is a key therapeutic goal in IBD and a better predictor of long-term outcomes than symptoms alone. A flexible sigmoidoscopy is the best way to evaluate this. If there is ongoing inflammation, management changes (e.g., dose optimization) may be considered. Checking drug levels can be useful, but objective assessment of inflammation is paramount. Switching therapy is premature without endoscopic assessment. Adding mesalamine is unlikely to provide significant benefit in a patient with moderate-to-severe disease already on a potent biologic.
A 38-year-old man who underwent a total proctocolectomy with ileal pouch-anal anastomosis (IPAA) for medically refractory ulcerative colitis 3 years ago presents with a 2-month history of increased stool frequency, abdominal cramping, and urgency. He denies fever or bloody stools. He has been well since his surgery.
Which of the following is the most likely diagnosis?
Explanation: Pouchitis, or inflammation of the ileal pouch, is the most common long-term complication after IPAA for ulcerative colitis. The symptoms of increased stool frequency, cramping, and urgency are classic for this condition. While Crohn disease of the pouch can occur, it is less common, especially if the original diagnosis was definitive UC. Irritable pouch syndrome is a diagnosis of exclusion. Small intestinal bacterial overgrowth typically presents with more bloating and flatulence. Given the inflammatory nature of the symptoms, pouchitis is the most probable diagnosis and is typically treated with antibiotics like ciprofloxacin or metronidazole.
A 25-year-old woman with moderate ulcerative colitis is scheduled to begin treatment with vedolizumab after failing mesalamine therapy. A review of her serologies shows she is non-immune to varicella (VZV IgG negative).
In addition to administering age-appropriate inactivated vaccines, which of the following is the most important recommendation regarding her vaccination status before starting therapy?
Explanation: Patients who are candidates for immunosuppressive biologic therapy should have their vaccination status updated prior to initiation. This is particularly critical for live vaccines, such as the varicella vaccine, which are contraindicated once immunosuppressive therapy has started. The vaccine series should be completed at least 4 weeks before the first dose of the biologic. VZIG is used for post-exposure prophylaxis, not for primary immunization.
A 22-year-old man with a 4-year history of IBD presents to the emergency department with 3 days of worsening abdominal pain, nausea, and vomiting. On examination, there is a tender, palpable mass in the right lower quadrant. An abdominal CT scan reveals a 5-cm inflammatory mass (phlegmon) involving the terminal ileum with associated small bowel obstruction.
This patient's underlying inflammatory bowel disease is most likely which of the following?
Explanation: The presence of a phlegmon, transmural inflammation, stricturing disease, and small bowel involvement (terminal ileum) are all characteristic features of Crohn disease. Ulcerative colitis is a mucosal disease limited to the colon and does not typically cause phlegmons or small bowel obstruction. Microscopic colitis causes watery diarrhea and has normal endoscopic findings. Indeterminate colitis is used when features overlap, but this presentation is strongly suggestive of Crohn disease.
A 28-year-old woman with a 5-year history of ileocolonic Crohn disease has been managed with azathioprine. For the past 3 months, she reports increasing abdominal pain, non-bloody diarrhea, and a 4-kg weight loss. Her C-reactive protein is 25 mg/L (normal <5 mg/L) and fecal calprotectin is 800 mcg/g (normal <50 mcg/g). Thiopurine metabolite testing shows 6-thioguanine nucleotide (6-TGN) levels in the therapeutic range.
Which of the following is the most appropriate next step in her management?
Explanation: This patient has active Crohn disease despite being on an optimized dose of azathioprine (as evidenced by therapeutic 6-TGN levels). This represents a failure of immunomodulator monotherapy. The next step is to escalate therapy by adding a biologic agent, such as the anti-TNF agent infliximab. Increasing azathioprine is incorrect as levels are already therapeutic. Switching to another immunomodulator like methotrexate is less effective than escalating to a biologic. Budesonide is used for short-term induction of remission but does not address the need for a change in long-term maintenance strategy.
A 30-year-old woman is newly diagnosed with severe Crohn disease with deep ileal ulcerations. A decision is made to initiate therapy with adalimumab. She feels well otherwise and has no cough, fever, or night sweats. She has a history of travel to Southeast Asia.
Which of the following screening tests is most critical to perform before administering the first dose of adalimumab?
Explanation: Anti-TNF agents like adalimumab can cause reactivation of latent tuberculosis (TB). Therefore, all patients must be screened for latent TB infection before initiating therapy. An interferon-gamma release assay (IGRA) or a tuberculin skin test are the standard screening methods. TPMT testing is done before starting thiopurines (azathioprine, 6-mercaptopurine). Hepatitis B screening is also important before starting anti-TNF therapy, but latent TB is a major contraindication and requires treatment before starting the biologic. A colonoscopy has likely already been done to make the diagnosis of Crohn's.