Lower Gastrointestinal Disorders

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USMLE Step 2 CK › Lower Gastrointestinal Disorders

Questions 1 - 10
1

A 45-year-old woman has hematochezia and colonoscopy shows continuous mucosal inflammation from rectum proximally; biopsy with crypt abscesses. What is the most likely diagnosis?

Ulcerative colitis

Irritable bowel syndrome

Celiac disease

Acute appendicitis

Diverticulitis

Explanation

This question tests the ability to diagnose and manage Lower Gastrointestinal Disorders, key for patient care in gastroenterology. Understanding common lower GI disorders involves recognizing symptoms, appropriate diagnostic tests, and management strategies. In the provided clinical vignette, the patient's history of hematochezia with colonoscopy showing continuous inflammation and crypt abscesses indicate ulcerative colitis. The correct answer, A, is justified by classic findings of UC, aligning with current guidelines for IBD diagnosis. Distractor B is incorrect due to IBS not causing inflammation or bleeding, often seen when overlooking endoscopic evidence. Teaching strategies include reinforcing guideline-based management, using case studies to illustrate typical presentations, and encouraging practice in ordering appropriate diagnostic tests. Emphasize the importance of differentiating similar GI conditions.

2

A 45-year-old woman has 2 months of intermittent hematochezia and fatigue; family history of colon cancer; exam shows no external hemorrhoids; CBC: Hgb 9.8. Next test?

Schedule follow-up in 1 year without further evaluation

Start NSAIDs for abdominal discomfort and observe

Reassure and treat presumptive hemorrhoids with topical therapy

Order stool ova and parasite examination only

Colonoscopy with biopsy to evaluate for colorectal neoplasia

Explanation

This question tests the ability to diagnose and manage Lower Gastrointestinal Disorders, key for patient care in gastroenterology. Understanding common lower GI disorders involves recognizing symptoms, appropriate diagnostic tests, and management strategies. In the provided clinical vignette, the patient's history of intermittent hematochezia, fatigue, family history, and anemia indicate possible colorectal cancer. The correct answer, A, is justified by colonoscopy for evaluation, aligning with current guidelines for bleeding with red flags. Distractor B is incorrect due to anemia requiring investigation beyond presumption, often seen when assuming hemorrhoids. Teaching strategies include reinforcing guideline-based management, using case studies to illustrate typical presentations, and encouraging practice in ordering appropriate diagnostic tests. Emphasize the importance of differentiating similar GI conditions.

3

A 30-year-old woman with suspected IBS reports symptoms triggered by dairy and wheat; no weight loss or bleeding; normal vitals. Which diagnostic test should be ordered next?

CT angiography to localize occult bleeding

Stool culture and ova/parasite testing regardless of chronicity

Urgent colonoscopy for all patients with IBS symptoms

Screen for celiac disease with tissue transglutaminase IgA and total IgA

ERCP to evaluate biliary obstruction

Explanation

This question tests the ability to diagnose and manage Lower Gastrointestinal Disorders, key for patient care in gastroenterology. Understanding common lower GI disorders involves recognizing symptoms, appropriate diagnostic tests, and management strategies. In the provided clinical vignette, the patient's history of IBS-like symptoms triggered by dairy and wheat indicate possible celiac disease overlap. The correct answer, A, is justified by screening for celiac in IBS with triggers, aligning with current guidelines for differential diagnosis. Distractor B is incorrect due to colonoscopy not first-line for IBS without alarms, often seen when escalating prematurely. Teaching strategies include reinforcing guideline-based management, using case studies to illustrate typical presentations, and encouraging practice in ordering appropriate diagnostic tests. Emphasize the importance of differentiating similar GI conditions.

4

A 50-year-old woman with IBS has diarrhea-predominant symptoms triggered by stress and coffee; exam normal. What dietary modification should be recommended?

Increase insoluble fiber aggressively to stop diarrhea

High-lactose diet to improve gut flora

Trial of low-FODMAP diet and avoidance of known triggers

Gluten-free diet without evaluating for celiac disease

Strict liquid-only diet for 2 weeks

Explanation

This question tests the ability to diagnose and manage Lower Gastrointestinal Disorders, key for patient care in gastroenterology. Understanding common lower GI disorders involves recognizing symptoms, appropriate diagnostic tests, and management strategies. In the provided clinical vignette, the patient's history of diarrhea-predominant IBS triggered by stress and coffee indicate dietary and lifestyle factors. The correct answer, A, is justified by low-FODMAP helping identify triggers, aligning with current guidelines for IBS management. Distractor B is incorrect due to insoluble fiber worsening diarrhea, often seen when misapplying constipation advice. Teaching strategies include reinforcing guideline-based management, using case studies to illustrate typical presentations, and encouraging practice in ordering appropriate diagnostic tests. Emphasize the importance of differentiating similar GI conditions.

5

A 30-year-old woman with IBS has frequent loose stools and urgency during exams; no alarm features; normal labs. What is the most appropriate initial management?

Dietary trigger avoidance and stress management with symptom-directed therapy

Immediate colectomy due to risk of perforation

Empiric broad-spectrum antibiotics for presumed infection

Hospitalization for IV fluids despite stable hydration

Chronic NSAID therapy for abdominal pain control

Explanation

This question tests the ability to diagnose and manage Lower Gastrointestinal Disorders, key for patient care in gastroenterology. Understanding common lower GI disorders involves recognizing symptoms, appropriate diagnostic tests, and management strategies. In the provided clinical vignette, the patient's history of loose stools and urgency with stress in IBS indicate diarrhea-predominant type. The correct answer, A, is justified by lifestyle and symptomatic management first, aligning with current guidelines for IBS. Distractor B is incorrect due to no evidence of infection, often seen when assuming infectious cause in chronic cases. Teaching strategies include reinforcing guideline-based management, using case studies to illustrate typical presentations, and encouraging practice in ordering appropriate diagnostic tests. Emphasize the importance of differentiating similar GI conditions.

6

A 35-year-old traveler has fever, tenesmus, and bloody diarrhea; stool leukocytes positive; no hypotension. Which diagnostic test should be ordered next?

Screening colonoscopy without stool studies

CT angiography of the abdomen and pelvis

Hydrogen breath test for lactose intolerance

Stool culture with Shiga toxin testing

Serum anti-tissue transglutaminase IgA level

Explanation

This question tests the ability to diagnose and manage Lower Gastrointestinal Disorders, key for patient care in gastroenterology. Understanding common lower GI disorders involves recognizing symptoms, appropriate diagnostic tests, and management strategies. In the provided clinical vignette, the patient's history of fever, tenesmus, bloody diarrhea, and positive stool leukocytes indicate invasive bacterial diarrhea. The correct answer, A, is justified by identifying pathogens like E. coli or Shigella, aligning with current guidelines for dysentery-like symptoms. Distractor C is incorrect due to no indication of vascular issues, often seen when mistaking for ischemic colitis. Teaching strategies include reinforcing guideline-based management, using case studies to illustrate typical presentations, and encouraging practice in ordering appropriate diagnostic tests. Emphasize the importance of differentiating similar GI conditions.

7

A 50-year-old woman with IBS reports worsening diarrhea after starting sertraline; no fever or blood; exam benign. Which medication should be adjusted or discontinued?

Stop loratadine due to increased stool frequency

Discontinue sertraline due to possible medication-associated diarrhea

Stop acetaminophen due to risk of colitis

Stop inhaled albuterol due to GI adverse effects

Stop lisinopril due to constipation risk

Explanation

This question tests the ability to diagnose and manage Lower Gastrointestinal Disorders, key for patient care in gastroenterology. Understanding common lower GI disorders involves recognizing symptoms, appropriate diagnostic tests, and management strategies. In the provided clinical vignette, the patient's history of worsening diarrhea after starting sertraline indicate medication side effect in IBS. The correct answer, A, is justified by SSRIs commonly causing diarrhea, aligning with current guidelines for medication review. Distractor B is incorrect due to acetaminophen not typically causing colitis, often seen when confusing analgesics. Teaching strategies include reinforcing guideline-based management, using case studies to illustrate typical presentations, and encouraging practice in ordering appropriate diagnostic tests. Emphasize the importance of differentiating similar GI conditions.

8

A 35-year-old man has acute diarrhea after travel; stool Shiga toxin positive, creatinine rising. Which complication is most likely to occur?

Hemolytic uremic syndrome with thrombocytopenia

Primary sclerosing cholangitis

Toxic megacolon requiring emergent colectomy

Acute pancreatitis from gallstone obstruction

Colorectal adenocarcinoma within weeks

Explanation

This question tests the ability to diagnose and manage Lower Gastrointestinal Disorders, key for patient care in gastroenterology. Understanding common lower GI disorders involves recognizing symptoms, appropriate diagnostic tests, and management strategies. In the provided clinical vignette, the patient's history of acute diarrhea after travel with positive Shiga toxin and rising creatinine indicate E. coli O157:H7 infection. The correct answer, B, is justified by risk of HUS in shiga-toxin producing infections, aligning with current guidelines for enterohemorrhagic E. coli. Distractor A is incorrect due to no evidence of toxic megacolon, often seen when confusing with C. difficile. Teaching strategies include reinforcing guideline-based management, using case studies to illustrate typical presentations, and encouraging practice in ordering appropriate diagnostic tests. Emphasize the importance of differentiating similar GI conditions.

9

A 50-year-old woman with IBS has 3 months of worsening watery diarrhea and nocturnal symptoms; weight loss; normal exam; basic labs normal. Which diagnostic test should be ordered next?

Abdominal radiograph to assess stool burden only

Colonoscopy with biopsies to evaluate for organic disease

Immediate loperamide and follow-up only if bleeding occurs

Empiric antibiotics for presumed IBS flare

Reassurance and no further workup due to IBS history

Explanation

This question tests the ability to diagnose and manage Lower Gastrointestinal Disorders, key for patient care in gastroenterology. Understanding common lower GI disorders involves recognizing symptoms, appropriate diagnostic tests, and management strategies. In the provided clinical vignette, the patient's history of worsening watery diarrhea, nocturnal symptoms, and weight loss indicate possible inflammatory or malabsorptive disorder beyond IBS. The correct answer, A, is justified by ruling out organic causes like IBD or cancer, aligning with current guidelines for alarm symptoms in IBS. Distractor C is incorrect due to presence of red flags requiring evaluation, often seen when underestimating nocturnal symptoms. Teaching strategies include reinforcing guideline-based management, using case studies to illustrate typical presentations, and encouraging practice in ordering appropriate diagnostic tests. Emphasize the importance of differentiating similar GI conditions.

10

A 50-year-old woman with IBS has chronic diarrhea; BMP shows hypokalemia; orthostasis on exam. Which complication is most likely to occur if untreated?

Acute appendicitis from gut dysmotility

Portal hypertension from chronic diarrhea

Cardiac arrhythmias due to electrolyte abnormalities

Aortic dissection due to dehydration

Hypercalcemia from volume depletion

Explanation

This question tests the ability to diagnose and manage Lower Gastrointestinal Disorders, key for patient care in gastroenterology. Understanding common lower GI disorders involves recognizing symptoms, appropriate diagnostic tests, and management strategies. In the provided clinical vignette, the patient's history of chronic diarrhea with hypokalemia and orthostasis indicate electrolyte imbalance from IBS. The correct answer, A, is justified by hypokalemia risking arrhythmias, aligning with current guidelines for complications. Distractor B is incorrect due to no link to portal hypertension, often seen when confusing with liver disease. Teaching strategies include reinforcing guideline-based management, using case studies to illustrate typical presentations, and encouraging practice in ordering appropriate diagnostic tests. Emphasize the importance of differentiating similar GI conditions.

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