USMLE Step 2 CK gastroenterology & hepatology questions

Patients with GERD symptoms that persist despite an adequate trial of once- or twice-daily PPI therapy should undergo upper endoscopy to evaluate for complications such as erosive esophagitis, Barrett esophagus, peptic stricture, or an alternative diagnosis like eosinophilic esophagitis. Endoscopy also allows biopsy if mucosal abnormalities are found. This step precedes further escalation of medical therapy or specialized pH testing. Identifying structural disease changes management and is the guideline-recommended next step in PPI-refractory GERD.

• A. Prokinetics are not first-line and do not address the need to rule out structural complications.
• B. Empirically increasing the PPI dose without endoscopic evaluation risks missing a structural or alternative diagnosis in refractory symptoms.
• C. Switching antisecretory class without first evaluating for structural disease is not the recommended next step.
• D. pH monitoring is used after endoscopy, typically to confirm reflux in patients being considered for anti-reflux surgery or with a normal endoscopy and continued symptoms.

Barrett esophagus without dysplasia confirmed on biopsy warrants surveillance endoscopy at an interval of 3 to 5 years, since the annual risk of progression to esophageal adenocarcinoma is low (approximately 0.3% per year). Ablative therapy such as radiofrequency ablation is reserved for confirmed dysplasia (low-grade or high-grade) or intramucosal carcinoma, not for nondysplastic Barrett esophagus. Continued PPI therapy is recommended to control reflux and reduce mucosal injury, not discontinued. Esophagectomy is reserved for invasive carcinoma or select high-grade dysplasia cases not amenable to endoscopic therapy.

• B. Ablation is reserved for dysplastic Barrett esophagus, not nondysplastic disease.
• C. Esophagectomy is not indicated for nondysplastic metaplasia.
• D. A 6-month interval is too frequent for nondysplastic Barrett esophagus and is used for indeterminate or low-grade dysplasia follow-up in some protocols, not this case.
• E. PPI therapy should be continued, not stopped, in Barrett esophagus.

Eosinophilic esophagitis typically presents in young adults, often with a personal history of atopy (asthma, allergic rhinitis, eczema), with intermittent dysphagia to solids and recurrent food impaction. Characteristic endoscopic findings include concentric rings ("trachealization"), longitudinal furrows, and whitish exudates; diagnosis requires biopsy showing greater than or equal to 15 eosinophils per high-power field. GERD can cause dysphagia but does not typically produce rings and furrows or occur in the setting of strong atopic history without heartburn. Squamous cell carcinoma and diffuse esophageal spasm present differently and at different demographics, and a single Schatzki ring causes impaction but not the diffuse furrowing and multiple ring pattern described.

• B. A solitary Schatzki ring causes intermittent solid food dysphagia but does not explain the furrows and atopic history seen here.
• C. Squamous cell carcinoma occurs in older patients, often with smoking/alcohol history and progressive dysphagia, not these endoscopic findings.
• D. Diffuse esophageal spasm presents with chest pain and dysphagia to both solids and liquids with a corkscrew pattern on imaging, not mucosal rings and furrows.
• E. GERD does not typically cause concentric rings and longitudinal furrows and this patient denies heartburn.

Esophageal manometry is the most accurate test for diagnosing achalasia, showing the characteristic findings of absent or incomplete peristalsis in the esophageal body and incomplete relaxation (elevated residual pressure) of the lower esophageal sphincter. Barium esophagram is useful for the classic bird's-beak appearance and dilated esophagus but is less sensitive and specific than manometry for confirming the diagnosis. Endoscopy is required first to exclude pseudoachalasia from mechanical obstruction or malignancy but cannot establish the motility diagnosis itself. pH monitoring assesses acid reflux and chest CT evaluates for secondary causes or complications, neither of which confirms the primary motor disorder.

• B. pH monitoring evaluates acid reflux, not esophageal motor function.
• C. Barium esophagram is supportive but less sensitive and specific than manometry for confirming achalasia.
• D. Chest CT may be used to exclude secondary causes but does not establish the manometric diagnosis.
• E. Endoscopy excludes mechanical or malignant causes but cannot diagnose the underlying motility disorder.

Esophageal squamous cell carcinoma is strongly associated with tobacco and alcohol use and classically arises in the mid-esophagus, reflecting direct mucosal injury from these carcinogens. Esophageal adenocarcinoma arises from chronic GERD-induced Barrett metaplasia and typically develops in the distal esophagus near the gastroesophageal junction, now the most common type of esophageal cancer in the United States. Recognizing these distinct risk factor and location patterns helps guide screening decisions, such as Barrett esophagus surveillance in chronic GERD patients. Leiomyosarcoma is a rare mesenchymal tumor unrelated to either risk factor profile described.

• A. Leiomyosarcoma is rare and not associated with smoking/alcohol or GERD/Barrett esophagus.
• B. Patient B's risk factors (GERD, Barrett esophagus) and distal location point to adenocarcinoma, not squamous cell carcinoma.
• C. Patient A's risk factors (smoking, alcohol) and mid-esophageal location point to squamous cell carcinoma, not adenocarcinoma.
• E. This reverses the classic associations: squamous cell carcinoma, not adenocarcinoma, is linked to smoking and alcohol.

Pill-induced esophagitis occurs when a tablet or capsule, especially doxycycline, tetracyclines, bisphosphonates, potassium chloride, or NSAIDs, lodges in the esophagus and causes direct mucosal injury, often because the patient took it with little water and then lay down. Prevention includes taking the medication with a full glass of water (at least 4 ounces) and remaining upright, sitting or standing, for at least 30 minutes afterward to ensure the pill passes completely into the stomach. Taking the drug with juice does not address the mechanical problem of inadequate fluid and recumbency. Crushing doxycycline is not recommended and does not prevent mucosal contact injury, and antacids or sublingual administration are not standard recommendations for preventing pill esophagitis from these agents.

• B. Orange juice does not address the key prevention measures of adequate water volume and remaining upright.
• C. Crushing the tablet is not a recommended or necessary strategy and does not address the lack of water and recumbency that caused the injury.
• D. Antacids are not a standard method for preventing pill-induced esophagitis.
• E. Sublingual administration is not how doxycycline or bisphosphonates are formulated or intended to be taken.

Plummer-Vinson syndrome consists of the triad of dysphagia due to an esophageal web, iron deficiency anemia, and glossitis, and occurs predominantly in middle-aged women. The iron deficiency is reflected by the microcytic anemia (MCV 68 fL) and low ferritin (6 ng/mL), while the glossy tongue and angular cheilitis are classic mucocutaneous signs of iron deficiency. The condition carries an increased risk for postcricoid squamous cell carcinoma, so treatment with iron repletion and endoscopic web dilation along with surveillance is important. Zenker diverticulum causes dysphagia with regurgitation and halitosis but is not linked to webs or iron deficiency, and the other distractors do not explain this combination of anemia, glossitis, and a cervical web.

• A. Squamous cell carcinoma can complicate longstanding Plummer-Vinson syndrome but this acute presentation with a thin web and anemia fits the syndrome itself rather than malignancy.
• C. Eosinophilic esophagitis presents with rings and furrows in atopic patients, not a cervical web with iron deficiency anemia.
• D. Diffuse esophageal spasm causes chest pain and dysphagia to solids and liquids with a corkscrew pattern, not a web with anemia and glossitis.
• E. Zenker diverticulum presents with regurgitation of undigested food and halitosis, typically in older patients, without the anemia and glossitis seen here.

A mucosal tear at the gastroesophageal junction from repeated forceful retching, presenting with hematemesis after several episodes of nonbloody vomiting, in a hemodynamically stable patient without signs of mediastinitis, is classic for a Mallory-Weiss tear. Boerhaave syndrome (full-thickness esophageal rupture) would present with severe chest pain, subcutaneous emphysema, and mediastinal air on imaging, none of which are present here. Most Mallory-Weiss tears stop bleeding spontaneously, and diagnosis is confirmed with upper endoscopy.

• A. Boerhaave syndrome involves full-thickness rupture with mediastinal air, crepitus, and severe pain, all absent in this stable patient.
• C. There is no rigidity, guarding, or free air to suggest perforation.
• D. Zenker diverticulum causes dysphagia and regurgitation of undigested food, not a bleeding tear from retching.
• E. There is no history of liver disease or portal hypertension to suggest varices.

Diverticulosis is the most common cause of acute lower GI bleeding in older adults, typically presenting as painless, large-volume maroon or bright red hematochezia, often with mild localized tenderness from the diverticula themselves rather than ischemia or malignancy. The colonoscopic finding of diverticula without other lesions supports this diagnosis. Bleeding results from mechanical disruption of a vasa recta at the dome or neck of a diverticulum and is usually self-limited. Angiodysplasia is also common in the elderly but classically causes slower, less dramatic bleeding and would appear as a vascular lesion on colonoscopy, not diverticula.

• B. Ischemic colitis typically causes crampy abdominal pain with bloody diarrhea and segmental colitis on imaging, not isolated diverticula.
• C. Angiodysplasia would appear as a cherry-red vascular lesion on colonoscopy, not as outpouchings, and this patient's colonoscopy shows diverticula.
• D. Hemorrhoids cause bright red blood coating the stool or on wiping, not large-volume maroon stool from a colonic source.
• E. Colorectal carcinoma usually causes occult or slowly progressive bleeding with weight loss, and no mass was seen on colonoscopy.

When upper and lower endoscopy fail to identify a source of overt or occult GI bleeding, the small bowel is the most likely culprit, and video capsule endoscopy is the next appropriate step because it allows direct visualization of the entire small bowel mucosa, which is inaccessible to standard endoscopy and colonoscopy. Common small bowel sources include angiodysplasia, small bowel tumors, and Crohn disease. Capsule endoscopy has high diagnostic yield and can guide subsequent therapeutic interventions such as push enteroscopy or angiography if a lesion is found.

• A. Mesenteric angiography requires active, brisk bleeding at the time of the study and is not appropriate for this stable patient with intermittent bleeding.
• C. Repeating EGD without new indication is unlikely to reveal a different source and delays appropriate workup of the small bowel.
• D. Tagged red blood cell scans require active bleeding to localize a source and are less sensitive than capsule endoscopy for obscure bleeding.
• E. Exploratory laparotomy is invasive and reserved for cases with a localized lesion or ongoing uncontrolled hemorrhage, not as an initial diagnostic step.

A restrictive transfusion strategy with a hemoglobin threshold of 7 g/dL is recommended for most patients with acute GI bleeding, including those with cirrhosis, because studies have shown improved survival and fewer rebleeding episodes compared with a liberal strategy. Overtransfusion in cirrhotic patients with portal hypertension can increase portal pressure and precipitate rebleeding. A higher threshold (around 9 g/dL) is reserved for patients with significant cardiovascular disease or hemodynamic instability refractory to resuscitation. This patient has no cardiac disease and is hemodynamically stable, so the restrictive threshold of 7 g/dL applies.

• B. A threshold of 9 g/dL is used for patients with significant comorbid cardiovascular disease, not for this patient.
• C. Fresh frozen plasma does not correct anemia and is reserved for coagulopathy, not for raising hemoglobin.
• D. Waiting until hemoglobin falls below 5 g/dL risks hemodynamic compromise and is lower than the evidence-based threshold.
• E. A threshold of 10 g/dL is not supported by evidence and risks overtransfusion, which can worsen portal hypertension in cirrhotic patients.

Acute pancreatitis is diagnosed when at least two of three criteria are present: characteristic abdominal pain, serum lipase or amylase greater than three times the upper limit of normal, and characteristic findings on imaging. This patient has typical epigastric pain radiating to the back and lipase markedly elevated above three times normal, which is sufficient for diagnosis without imaging. Initial management focuses on aggressive isotonic crystalloid fluid resuscitation to prevent complications such as pancreatic necrosis and organ failure, along with analgesia and bowel rest. CT is not required for diagnosis when clinical and laboratory criteria are already met and is typically reserved for cases with diagnostic uncertainty or suspected complications.

• B. ERCP is not a diagnostic test for pancreatitis and is reserved for cases with cholangitis or obstructing choledocholithiasis.
• C. CT is unnecessary when two of three diagnostic criteria (pain and markedly elevated lipase) are already met, and early CT may understage severity.
• D. Amylase does not need to be measured separately once lipase is markedly elevated and typical pain is present; lipase is more sensitive and specific.
• E. Antibiotics are not indicated empirically in uncomplicated acute pancreatitis without evidence of infected necrosis.

In patients with mild gallstone pancreatitis, laparoscopic cholecystectomy should be performed during the same hospital admission once the episode resolves clinically, because delaying surgery significantly increases the risk of recurrent pancreatitis, cholangitis, or other biliary complications before an outpatient procedure can be arranged. This patient's pancreatitis has resolved as evidenced by resolved pain, tolerance of oral intake, and downtrending lipase, making her a candidate for same-admission cholecystectomy. Delaying surgery for 6 weeks or until symptoms recur is outdated practice and associated with higher readmission rates for recurrent biliary events.

• A. Waiting for symptom recurrence exposes the patient to preventable repeat episodes of pancreatitis or cholangitis.
• B. Sphincterotomy alone does not remove the gallbladder and does not eliminate the risk of future gallstone-related complications such as cholecystitis.
• C. Delaying cholecystectomy for weeks increases the risk of recurrent gallstone-related complications before surgery.
• E. Ursodeoxycholic acid is used for cholesterol gallstone dissolution in non-surgical candidates, not as standard therapy after gallstone pancreatitis.

This patient has chronic pancreatitis with exocrine insufficiency, evidenced by steatorrhea, weight loss, and low fecal elastase. Pancreatic enzyme replacement therapy (pancrelipase) taken with meals replaces deficient lipase, amylase, and protease, improving fat digestion and absorption and reducing steatorrhea. Enteric-coated or non-enteric formulations are typically combined with acid suppression (H2 blocker or PPI) to prevent enzyme degradation by gastric acid. This is the cornerstone of managing exocrine pancreatic insufficiency from chronic pancreatitis.

• A. Metoclopramide is a prokinetic used for gastroparesis or nausea and does not address fat malabsorption from enzyme deficiency.
• C. Vitamin B12 deficiency is not the primary problem here; steatorrhea in chronic pancreatitis results from enzyme deficiency, not B12 malabsorption.
• D. Ursodeoxycholic acid is used in cholestatic liver diseases such as primary biliary cholangitis, not for pancreatic exocrine insufficiency.
• E. Octreotide suppresses pancreatic and gastrointestinal secretions and is used for conditions like variceal bleeding or carcinoid syndrome, not for correcting exocrine enzyme deficiency.

Painless obstructive jaundice with a palpable, non-tender, distended gallbladder (Courvoisier sign) in an older patient with significant weight loss and smoking history strongly suggests a malignant obstruction of the common bile duct, most commonly from adenocarcinoma arising in the pancreatic head. The tumor compresses the distal common bile duct, causing gradual, painless biliary dilation and a palpably distended but non-inflamed gallbladder, unlike the pain and tenderness seen with gallstone disease. CA 19-9 is a tumor marker frequently elevated in pancreatic adenocarcinoma and supports this diagnosis, though imaging (CT) is needed for confirmation.

• A. Hepatocellular carcinoma typically presents with signs of underlying cirrhosis and elevated alpha-fetoprotein, not painless jaundice with Courvoisier sign.
• B. Choledocholithiasis usually causes colicky pain and is less likely to produce a painlessly distended, palpable gallbladder; it does not typically elevate CA 19-9.
• C. Primary sclerosing cholangitis classically presents in younger patients, often with inflammatory bowel disease, and does not typically cause a palpable distended gallbladder or markedly elevated CA 19-9.
• D. Acute cholecystitis typically presents with right upper quadrant pain, tenderness, and fever (Murphy sign), not painless jaundice with a non-tender gallbladder.

Fever, leukocytosis, and sustained right upper quadrant pain with a positive physical and sonographic Murphy sign, combined with ultrasound findings of gallbladder wall thickening (greater than 3 mm) and pericholecystic fluid, are diagnostic of acute cholecystitis. In contrast, biliary colic from gallstones alone causes transient pain without fever, leukocytosis, or these inflammatory sonographic findings, as there is no persistent cystic duct obstruction with inflammation. The combination of clinical and imaging criteria here fulfills the Tokyo Guidelines for acute cholecystitis.

• A. Choledocholithiasis without cholangitis would show a dilated common bile duct or visible stone in the duct, not primarily gallbladder wall inflammation.
• B. Chronic cholecystitis reflects longstanding, recurrent inflammation with a shrunken, fibrotic gallbladder, not the acute inflammatory findings seen here.
• D. Biliary colic causes self-limited pain from transient cystic duct obstruction without fever, leukocytosis, or gallbladder wall thickening on imaging.
• E. Acute pancreatitis presents with epigastric pain radiating to the back and elevated lipase, not gallbladder wall thickening with a positive Murphy sign.

Early laparoscopic cholecystectomy, ideally within 72 hours (and up to 7 days) of symptom onset, is the preferred management for acute cholecystitis in patients who are good surgical candidates, as it is associated with lower complication rates and shorter hospital stays compared with delayed surgery. This patient has uncomplicated acute cholecystitis with no evidence of choledocholithiasis or cholangitis, so ERCP is not indicated. Percutaneous cholecystostomy is reserved for patients who are poor surgical candidates due to severe comorbidities or critical illness.

• A. Percutaneous cholecystostomy is reserved for patients unfit for surgery, not for a good surgical candidate with uncomplicated acute cholecystitis.
• B. Antibiotics alone without surgery leads to high rates of recurrence and complications; definitive treatment requires cholecystectomy.
• C. ERCP is indicated only when there is evidence of choledocholithiasis or cholangitis, which is absent here given the normal common bile duct on ultrasound.
• E. Delaying cholecystectomy for 6 weeks increases the risk of recurrent biliary complications; early surgery during the same admission is preferred.

This patient has acute cholangitis with Reynolds pentad (fever, jaundice, right upper quadrant pain, confusion, and hypotension), indicating severe, life-threatening biliary obstruction with sepsis. After initial resuscitation with fluids, antibiotics, and vasopressor support, urgent biliary decompression via ERCP is required to relieve the obstruction and drain infected bile, which is both diagnostic and therapeutic. Delaying decompression in this unstable patient risks progression to septic shock and death.

• A. MRCP is a diagnostic imaging study and does not provide therapeutic drainage; it would delay urgent decompression needed in this critically ill patient.
• B. Repeating ultrasound delays definitive treatment in a hemodynamically unstable patient with confirmed choledocholithiasis and sepsis.
• C. Cholecystectomy addresses the gallbladder but does not relieve the common bile duct obstruction causing cholangitis; biliary decompression via ERCP takes priority in this unstable patient.
• E. Ursodeoxycholic acid is used for cholestatic liver diseases and gallstone dissolution, not for emergent decompression of an obstructed, infected bile duct.

Primary sclerosing cholangitis is strongly associated with ulcerative colitis and presents with a cholestatic liver profile (elevated alkaline phosphatase, pruritus) and a characteristic MRCP finding of multifocal biliary strictures with intervening dilations, producing a beaded appearance of the bile ducts. Antimitochondrial antibody is typically negative, which helps distinguish it from primary biliary cholangitis. The combination of inflammatory bowel disease history and this classic cholangiographic pattern is diagnostic.

• A. Primary biliary cholangitis is associated with a positive antimitochondrial antibody, which is negative here, and does not cause the beaded biliary strictures seen on MRCP.
• B. Choledocholithiasis causes a single obstructing stone with duct dilation proximal to it, not the multifocal beaded strictures throughout the intrahepatic and extrahepatic ducts.
• C. Secondary biliary cirrhosis results from chronic mechanical bile duct obstruction such as recurrent stones or strictures from prior surgery, not from an association with ulcerative colitis.
• E. Autoimmune hepatitis typically presents with a hepatocellular pattern of liver injury and autoantibodies such as ANA or anti-smooth muscle antibody, not biliary strictures on MRCP.

A middle-aged woman with cholestatic liver enzymes (elevated alkaline phosphatase and GGT with normal bilirubin), pruritus, fatigue, and a history of another autoimmune condition such as hypothyroidism is a classic presentation of primary biliary cholangitis. Antimitochondrial antibody is positive in over 90% of cases and is both highly sensitive and specific, making it the best confirmatory test when combined with the cholestatic pattern and normal biliary imaging. Liver biopsy is reserved for cases with atypical serology or diagnostic uncertainty.

• A. Perinuclear ANCA is associated with primary sclerosing cholangitis and autoimmune hepatitis, not primary biliary cholangitis.
• B. Serum ceruloplasmin is used to evaluate for Wilson disease, which typically presents in younger patients with neuropsychiatric symptoms or hepatocellular injury, not this cholestatic picture.
• D. Hepatitis C causes a hepatocellular pattern of liver injury rather than the cholestatic pattern seen here, and there is no risk factor history suggesting viral hepatitis.
• E. Anti-smooth muscle antibody is associated with autoimmune hepatitis, which causes a hepatocellular rather than cholestatic enzyme pattern.

A positive hepatitis B surface antibody with a negative hepatitis B core antibody and negative surface antigen indicates immunity from vaccination rather than natural infection, because vaccination induces antibody only to surface antigen, not to core antigen. In contrast, immunity from natural infection would show both positive surface antibody and positive core antibody (reflecting prior exposure to the whole virus). This distinction is clinically important for determining whether prior natural infection with potential for reactivation needs to be considered before immunosuppression.

• B. The window period is characterized by negative surface antigen, negative surface antibody, and positive IgM core antibody, which does not match this patient's panel.
• C. Acute infection presents with positive surface antigen and positive IgM core antibody, neither of which is present in this panel.
• D. Chronic infection requires a positive hepatitis B surface antigen persisting beyond 6 months, which is negative here.
• E. Immunity from natural infection requires a positive hepatitis B core antibody, reflecting prior exposure to the complete virus, which is negative in this patient.

The CDC and USPSTF recommend one-time universal hepatitis C screening for all adults aged 18 years and older, regardless of risk factors or prevalence, because most infected individuals are asymptomatic and risk-based screening misses many cases. The initial test is an HCV antibody assay; if positive, it must be followed by HCV RNA testing to confirm active, current infection versus past cleared infection. Liver enzymes and imaging are not sensitive or specific enough to serve as screening tools. Universal screening allows earlier identification of candidates for direct-acting antiviral therapy, which can cure over 95% of cases.

• A. RNA testing is used to confirm active infection after a positive antibody test, not as the initial screening test.
• B. Universal one-time screening is recommended for all adults regardless of risk factors.
• C. ALT can be normal in chronic HCV infection and is not an adequate screening tool.
• E. Ultrasound evaluates liver structure and is not a screening test for hepatitis C exposure.

Infants born to HBsAg-positive mothers should receive both the hepatitis B vaccine and hepatitis B immune globulin (HBIG) within 12 hours of birth, administered at different injection sites. This combination provides immediate passive protection from HBIG while the vaccine stimulates active, long-term immunity, reducing perinatal transmission risk by over 90%. The infant should complete the full vaccine series and undergo post-vaccination serologic testing for HBsAg and anti-HBs at 9-12 months of age. Maternal antiviral therapy (e.g., tenofovir) late in pregnancy is reserved for mothers with high viral loads to further reduce transmission risk, not as infant prophylaxis.

• A. Vaccine alone is insufficient; HBIG provides essential immediate passive immunity in exposed infants.
• C. HBIG alone offers only temporary protection without the active immunity provided by vaccination.
• D. Immunoprophylaxis must be given within 12 hours of birth, not delayed.
• E. Tenofovir is used in selected mothers during pregnancy, not as a newborn prophylactic agent.

The Rumack-Matthew nomogram plots serum acetaminophen concentration against time since ingestion (used for levels drawn between 4 and 24 hours) to predict hepatotoxicity risk. A 4-hour level of 180 mcg/mL falls above the treatment line (150 mcg/mL at 4 hours), indicating high risk of liver injury and the need for N-acetylcysteine therapy. NAC replenishes glutathione stores, allowing detoxification of the toxic metabolite NAPQI, and is most effective when started within 8-10 hours of ingestion. Activated charcoal may have been useful earlier but does not replace the need for NAC once levels indicate toxicity risk.

• A. Charcoal alone is inadequate; her level is above the nomogram treatment threshold and requires NAC.
• B. Liver biopsy has no role in acute management decisions for acetaminophen overdose.
• D. Discharge is inappropriate given a toxic level requiring antidotal therapy.
• E. Waiting 24 hours delays essential treatment and risks progression to hepatotoxicity.

This patient has severe alcoholic hepatitis, indicated by a Maddrey discriminant function score of 32 or greater, along with the characteristic AST:ALT ratio greater than 2:1 reflecting mitochondrial injury from alcohol rather than viral hepatitis (where ALT typically exceeds AST). Corticosteroids, specifically prednisolone, are the treatment of choice in severe alcoholic hepatitis to reduce short-term mortality by suppressing the inflammatory cytokine cascade, provided there is no active infection or gastrointestinal bleeding. The Lille score at day 7 is used to assess response and guide whether to continue or discontinue steroids. Pentoxifylline is no longer favored as an alternative given weaker mortality benefit evidence in recent trials.

• A. Ursodeoxycholic acid is used in cholestatic liver diseases such as primary biliary cholangitis, not alcoholic hepatitis.
• B. Pentoxifylline monotherapy has shown inferior and inconsistent mortality benefit compared to corticosteroids in current evidence.
• D. Lactulose treats hepatic encephalopathy but does not address the underlying inflammatory liver injury.
• E. Rifaximin is used for hepatic encephalopathy prophylaxis, not for treating severe alcoholic hepatitis itself.

In patients with suspected metabolic dysfunction-associated steatotic liver disease (MASLD) and risk factors such as diabetes and obesity, the recommended stepwise approach begins with a noninvasive fibrosis risk score such as FIB-4, calculated from age, AST, ALT, and platelet count. A low FIB-4 score effectively rules out advanced fibrosis, while an indeterminate or high score prompts further evaluation with vibration-controlled transient elastography or MR elastography, and biopsy is reserved for cases that remain unclear or require definitive histologic diagnosis. This stepwise strategy avoids unnecessary invasive testing in low-risk patients while identifying those needing specialist referral. Autoimmune markers are not part of fibrosis staging in MASLD.

• B. Simple observation without risk stratification delays identification of advanced fibrosis.
• C. Autoimmune antibodies are used to evaluate for autoimmune hepatitis, not to stage fibrosis in MASLD.
• D. Elastography is appropriate after an indeterminate or high FIB-4 score, not as the first test.
• E. Biopsy is invasive and reserved for cases with indeterminate noninvasive results, not the initial step.

This patient's presentation, young woman with another autoimmune condition, elevated transaminases, hyperglobulinemia, and negative viral serologies, is classic for autoimmune hepatitis. Serologic workup typically shows positive ANA and/or anti-smooth muscle antibody, and liver biopsy characteristically demonstrates interface hepatitis with a dense lymphoplasmacytic infiltrate extending from the portal tract into the hepatic lobule. This histologic pattern reflects immune-mediated attack on hepatocytes and supports the diagnosis when combined with clinical and serologic findings per the simplified diagnostic criteria. Treatment involves corticosteroids, often combined with azathioprine for maintenance.

• A. Steatosis with Mallory-Denk bodies is characteristic of alcoholic or metabolic steatohepatitis, not autoimmune hepatitis.
• B. Ground-glass hepatocytes are characteristic of chronic hepatitis B infection.
• C. Periportal iron deposition suggests hereditary hemochromatosis.
• E. Granulomatous bile duct destruction is characteristic of primary biliary cholangitis.

Hereditary hemochromatosis due to HFE C282Y homozygosity causes increased intestinal iron absorption, leading to progressive iron deposition in the liver, pancreas, joints, and skin, producing the classic triad of diabetes, bronze skin pigmentation, and hepatomegaly ('bronze diabetes'). Therapeutic phlebotomy is the first-line treatment, removing iron-laden red blood cells to reduce total body iron burden, typically performed weekly until ferritin normalizes, then continued periodically for maintenance. Early treatment before cirrhosis develops can prevent progression of organ damage and normalize life expectancy. Chelation therapy is reserved for patients who cannot tolerate phlebotomy, such as those with significant anemia.

• A. Dietary iron restriction alone is insufficient to reduce the substantial iron overload seen in hemochromatosis.
• C. Interferon has no role in the treatment of hereditary hemochromatosis.
• D. Transplantation is reserved for decompensated cirrhosis or hepatocellular carcinoma, not early uncomplicated disease.
• E. Chelation is reserved for patients unable to undergo phlebotomy, such as those with anemia or cardiac compromise.

The combination of early-onset panacinar emphysema (particularly in a nonsmoker), liver disease, and PAS-positive, diastase-resistant globules in periportal hepatocytes on biopsy is characteristic of alpha-1 antitrypsin deficiency. This autosomal codominant disorder results from misfolded alpha-1 antitrypsin protein (most commonly the Z allele) that accumulates in the endoplasmic reticulum of hepatocytes, causing liver injury, while the resulting lack of circulating antiprotease allows unchecked neutrophil elastase activity in the lungs, causing emphysema. Diagnosis is confirmed by measuring serum alpha-1 antitrypsin level and genotyping. The family history of early liver and lung disease supports the autosomal inheritance pattern.

• A. Wilson disease causes liver and neuropsychiatric disease, not emphysema, and biopsy would show copper accumulation.
• B. NASH is associated with metabolic syndrome and does not cause early emphysema or PAS-positive globules.
• D. Hemochromatosis causes liver disease with bronze skin and diabetes, not emphysema, and biopsy would show iron deposition.
• E. Primary biliary cholangitis causes cholestatic liver disease in middle-aged women and is not associated with emphysema.

Vibration-controlled transient elastography (FibroScan) is the preferred best initial noninvasive test to assess liver stiffness and screen for fibrosis or cirrhosis in patients with chronic liver disease such as NAFLD, as it correlates well with fibrosis stage and avoids the risks of an invasive procedure. Liver biopsy remains the gold standard for staging fibrosis but is reserved for cases where noninvasive testing is indeterminate or discordant with clinical suspicion, given its invasiveness and sampling variability. Elastography can be repeated to monitor disease progression without procedural risk. If elastography results are inconclusive, biopsy may be pursued for definitive histologic assessment.

• A. Biopsy is the gold standard but is invasive with bleeding risk and is reserved for indeterminate noninvasive results.
• B. Hepatic venous pressure gradient measures portal hypertension severity, not an initial screening test for fibrosis.
• C. CT scan can suggest advanced cirrhosis but is not sensitive for detecting earlier stages of fibrosis.
• D. Hyaluronic acid is a research biomarker, not a standard validated noninvasive test for routine clinical use.

Nonselective beta-blockers such as nadolol or propranolol are first-line therapy for primary prophylaxis against variceal hemorrhage in patients with medium or large esophageal varices, as they reduce portal pressure by decreasing cardiac output and splanchnic blood flow. Endoscopic variceal ligation is an alternative primary prophylaxis option, particularly for patients who cannot tolerate beta-blockers, but is not simply reserved until after a bleed occurs. Proton pump inhibitors have no role in preventing variceal bleeding. Octreotide and terlipressin are used for acute variceal hemorrhage, not primary prevention.

• A. Waiting until bleeding occurs is incorrect because primary prophylaxis with beta-blockers or ligation should begin now given medium-sized varices.
• B. Terlipressin is used for acute variceal hemorrhage and hepatorenal syndrome, not for primary prophylaxis.
• D. Proton pump inhibitors treat acid-related disease, not portal hypertension, and have no role in variceal prophylaxis.
• E. Octreotide is used for acute variceal bleeding, not primary prevention.

Patients with cirrhosis presenting with acute gastrointestinal bleeding should receive short-term antibiotic prophylaxis (typically intravenous ceftriaxone or oral norfloxacin for 7 days) regardless of ascitic fluid neutrophil count or protein level, as bacterial infection is a common precipitant and complication of variceal hemorrhage. This prophylaxis reduces the incidence of bacterial infections including SBP, decreases rebleeding risk, and improves survival. Other established indications for SBP prophylaxis include prior episode of SBP (secondary prophylaxis) and ascitic fluid protein below 1.5 g/dL with additional risk factors such as renal or hepatic impairment. The current neutrophil count below 250 cells/mm³ indicates no active SBP, but prophylaxis is still warranted because of the GI bleed itself.

• A. Antibiotic prophylaxis is still indicated in acute variceal bleeding regardless of current neutrophil count, which only rules out active infection, not future risk.
• B. Prophylaxis should begin now in the setting of active GI bleeding, not deferred based on future protein levels.
• C. Metronidazole targets anaerobes and is not the guideline-recommended prophylactic regimen for GI bleeding in cirrhosis.
• D. Antibiotics should be started immediately at the time of GI bleeding rather than delayed for repeat paracentesis.

Lactulose, a nonabsorbable disaccharide, is first-line therapy for hepatic encephalopathy; it is metabolized by colonic bacteria to acidic byproducts that trap ammonia as ammonium and promote its excretion, with the dose titrated to achieve 2 to 3 soft bowel movements daily. In this patient, constipation is the identifiable precipitating factor leading to increased ammonia absorption and encephalopathy. Rifaximin, a nonabsorbable antibiotic that reduces ammonia-producing gut bacteria, is added for patients with recurrent or breakthrough encephalopathy despite lactulose, but is not used as monotherapy without lactulose. Protein restriction is not recommended in current guidelines, as adequate protein intake is needed to prevent malnutrition and sarcopenia in cirrhosis.

• A. Mannitol is used for cerebral edema from other causes, not for hepatic encephalopathy in cirrhosis.
• B. Severe protein restriction is no longer recommended and can worsen malnutrition and sarcopenia.
• C. There is no fever or other evidence of infection to support empiric antibiotics for infection in this scenario.
• E. Rifaximin is add-on therapy for refractory or recurrent encephalopathy, not monotherapy without lactulose.

All patients with cirrhosis, regardless of etiology, should undergo hepatocellular carcinoma (HCC) surveillance with abdominal ultrasound every 6 months, with or without serum alpha-fetoprotein (AFP), per AASLD guidelines. This interval balances the tumor doubling time of HCC with cost and radiation/contrast exposure concerns. Ultrasound is preferred as the initial screening modality because it is noninvasive, inexpensive, and does not involve radiation or contrast. CT and MRI are reserved for further characterization of a liver lesion detected on ultrasound, not for routine first-line surveillance.

• A. Every 3 months is more frequent than needed given HCC's typical doubling time, increasing cost and false positives without proven benefit.
• B. AFP alone has low sensitivity and specificity for HCC and should not be used without imaging.
• C. CT surveillance every 6 months exposes patients to unnecessary radiation and contrast and is not the recommended first-line modality.
• E. MRI annually is not the standard surveillance interval or first-line modality; it is reserved for indeterminate ultrasound findings.

The Model for End-Stage Liver Disease (MELD-Na) score uses serum bilirubin, creatinine, INR, and sodium to estimate 90-day mortality in patients with cirrhosis. The United Network for Organ Sharing (UNOS) uses this score to prioritize patients for deceased-donor liver allocation, with higher scores reflecting higher short-term mortality risk and thus higher transplant priority. Dialysis status is incorporated by setting creatinine to 4.0 mg/dL if the patient received two or more dialysis sessions in the prior week. The score does not directly measure encephalopathy, long-term post-transplant survival, or variceal bleeding risk, although it correlates with overall disease severity.

• A. MELD does not calculate variceal bleeding risk; it reflects overall liver disease severity and short-term mortality.
• C. MELD is used for all liver allocation, not solely to determine candidacy for combined liver-kidney transplant, which uses separate criteria.
• D. Hepatic encephalopathy severity is part of the Child-Pugh score, not a direct component of MELD.
• E. MELD predicts short-term (90-day) pretransplant mortality, not long-term post-transplant outcomes.

Crohn disease characteristically causes skip lesions (patchy inflammation with intervening normal mucosa), can affect any part of the GI tract including the terminal ileum, and often spares the rectum. Transmural inflammation with noncaseating granulomas on histology and perianal fistulizing disease are hallmark features distinguishing Crohn disease from ulcerative colitis. Ulcerative colitis, in contrast, produces continuous mucosal (not transmural) inflammation that begins in the rectum and extends proximally without skip areas or granulomas. The combination of ileocecal involvement, skip lesions, granulomas, and perianal fistula is classic for Crohn disease.

• A. Diverticulitis presents with localized sigmoid colon inflammation, not ileocecal skip lesions with granulomas and fistula formation.
• B. Ulcerative colitis causes continuous rectal-based mucosal inflammation without skip lesions, granulomas, or fistulizing disease.
• C. Infectious colitis is typically acute and self-limited, and biopsy would show acute inflammation, not granulomas or transmural disease.
• E. Ischemic colitis typically occurs in older patients with vascular risk factors and affects watershed areas, not the terminal ileum with granulomas.

Primary sclerosing cholangitis (PSC) is an independent risk factor for colorectal cancer in patients with ulcerative colitis, substantially increasing risk beyond disease duration alone. Current guidelines recommend that patients with concurrent IBD and PSC begin annual surveillance colonoscopy with biopsies at the time of PSC diagnosis, regardless of UC duration, rather than waiting for the standard 8-year mark used in UC without PSC. This reflects the markedly elevated cumulative cancer risk associated with the PSC-IBD overlap. Average-risk screening ages and noninvasive markers like fecal calprotectin are not substitutes for surveillance colonoscopy in this high-risk group.

• A. Mesalamine may have a modest chemopreventive effect but does not eliminate the need for surveillance colonoscopy in high-risk patients.
• B. Fecal calprotectin reflects inflammatory activity, not dysplasia or cancer risk, and cannot replace colonoscopic surveillance.
• D. The 8-year-after-diagnosis, every 1-3-year interval applies to UC patients without PSC; PSC accelerates the need for annual surveillance starting now.
• E. Average-risk screening starting at age 45 is inadequate given his markedly elevated risk from longstanding pancolitis plus PSC.

This patient has a fibrotic stricture causing partial small bowel obstruction, evidenced by luminal narrowing with proximal dilation and no active inflammatory changes or abscess on CT. Fibrotic strictures do not respond to anti-inflammatory or immunosuppressive therapy because the narrowing results from chronic fibrosis, not active inflammation; management requires bowel rest, decompression, and surgical evaluation for resection or strictureplasty if obstruction does not resolve or recurs. Biologics and steroids are effective for inflammatory (not fibrotic) strictures and for luminal disease activity, not fixed fibrotic narrowing. Percutaneous drainage is used for abscesses, which are not present here.

• A. Escalating mesalamine will not resolve a mechanical obstruction from fibrotic stricture and risks worsening obstruction if oral intake continues.
• B. Infliximab targets active inflammation and is ineffective for a fibrotic stricture causing mechanical obstruction.
• C. Percutaneous drainage is indicated for abscess, not for a fibrotic stricture without fluid collection.
• E. Corticosteroids treat inflammatory flares, not fixed fibrotic strictures, and will not relieve the obstruction.

This patient has moderately active ulcerative colitis refractory to an adequate trial of 5-aminosalicylic acid (5-ASA) therapy. The standard step-up approach is to add oral corticosteroids to induce remission in 5-ASA-refractory or moderate-to-severe disease. Biologics such as anti-TNF agents (infliximab) are reserved for steroid-refractory, steroid-dependent, or more severe disease, not as the first step after 5-ASA failure in a patient without severe or fulminant features. Azathioprine has a slow onset of action (weeks to months) and is used for maintenance or steroid-sparing therapy, not for inducing remission in an acute flare.

• A. Oral vancomycin treats Clostridioides difficile infection, which has been excluded by negative stool studies.
• B. Azathioprine has a delayed onset of action and is not used to induce remission in an active flare.
• C. He is already on maximal-dose mesalamine with inadequate response, so further dose escalation is unlikely to help.
• D. Infliximab is typically reserved for steroid-refractory or steroid-dependent disease, not as first-line therapy immediately after 5-ASA failure in moderate disease.

This patient has toxic megacolon, diagnosed by colonic dilation greater than 6 cm with loss of haustration on imaging plus systemic toxicity (fever, tachycardia, leukocytosis). Initial management is medical: bowel rest, nasogastric decompression if needed, IV fluid resuscitation, broad correction of electrolyte abnormalities, and IV corticosteroids to control the underlying inflammatory flare, combined with early surgical consultation because perforation risk is high and colectomy is required if there is no rapid improvement within 24-72 hours. Colonoscopy is contraindicated due to perforation risk. Antidiarrheal agents are contraindicated because they can worsen or precipitate toxic megacolon.

• A. This is a surgical emergency requiring hospitalization and close monitoring, not outpatient management.
• B. Antidiarrheal agents are contraindicated in toxic megacolon as they can precipitate or worsen colonic dilation and perforation.
• C. Colonoscopy is contraindicated in toxic megacolon because of the high risk of perforation from colonic distention.
• D. Vancomycin and metronidazole target C. difficile infection, which has not been established here, and do not address the underlying UC flare or impending perforation risk.

IgA anti-tissue transglutaminase (tTG-IgA) antibody testing is the preferred initial serologic test for celiac disease because of its high sensitivity and specificity while the patient remains on a gluten-containing diet. A positive result is followed by esophagogastroduodenoscopy with duodenal biopsy showing villous atrophy, intraepithelial lymphocytosis, and crypt hyperplasia to confirm the diagnosis. Testing must be performed before starting a gluten-free diet, since dietary restriction can normalize antibody titers and biopsy findings. Total serum IgA should be checked concurrently to exclude IgA deficiency, which can cause a false-negative tTG-IgA result.

• A. Small bowel imaging is not a standard diagnostic test for celiac disease and would not confirm the diagnosis.
• B. Giardia stool antigen testing is used for suspected giardiasis, which typically follows travel or contaminated water exposure, not described here.
• C. Fecal fat quantification evaluates for generalized fat malabsorption but is not specific for celiac disease and is not the first step.
• D. A hydrogen breath test evaluates for lactose intolerance, which is a separate condition and does not explain the weight loss and anemia pattern seen here.

Lactose intolerance results from a relative deficiency of intestinal lactase, leading to undigested lactose reaching the colon where bacterial fermentation produces gas, bloating, and osmotic diarrhea. The temporal relationship between dairy ingestion and symptom onset, tolerance of low-lactose dairy products like aged cheese and yogurt, and absence of alarm features strongly support this diagnosis. A hydrogen breath test or empirical lactose elimination with symptom resolution can confirm the diagnosis. Normal tTG-IgA and absence of weight loss or anemia make celiac disease and inflammatory bowel disease unlikely.

• A. Irritable bowel syndrome does not typically show such a tight temporal link to a single specific food trigger.
• B. Celiac disease is excluded by the normal tTG-IgA antibody level and lack of symptoms with gluten-containing, non-dairy foods.
• D. Small intestinal bacterial overgrowth usually causes more constant symptoms unrelated to specific foods and often occurs with predisposing anatomic or motility disorders.
• E. Crohn disease would be expected to cause weight loss, systemic symptoms, or abnormal inflammatory markers, none of which are present.

Oral vancomycin (or alternatively oral fidaxomicin) is first-line therapy for an initial episode of C. difficile infection according to current IDSA/SHEA guidelines, regardless of severity, replacing the older recommendation for metronidazole in mild-moderate cases. Oral vancomycin acts locally within the colonic lumen, achieving high local concentrations with minimal systemic absorption, which is ideal for treating this luminal infection. Intravenous vancomycin is not useful because it does not achieve adequate concentrations in the colon. Metronidazole is now reserved for use in combination with oral vancomycin in fulminant disease or when vancomycin and fidaxomicin are unavailable.

• A. Intravenous metronidazole does not achieve adequate luminal colonic concentrations and is not first-line therapy.
• B. Intravenous vancomycin does not reach the colonic lumen in adequate concentrations and is ineffective for this indication.
• D. Rifaximin is not a standard first-line treatment for C. difficile infection and carries risk of resistance development.
• E. Oral metronidazole is no longer recommended as first-line therapy due to inferior efficacy compared to vancomycin or fidaxomicin.

This patient has uncomplicated acute diverticulitis, defined by CT findings of localized inflammation without abscess, perforation, obstruction, or fistula, and he is hemodynamically stable with no signs of peritonitis. Current guidelines support outpatient management with oral antibiotics (such as ciprofloxacin plus metronidazole, or amoxicillin-clavulanate) and a clear liquid diet advanced as tolerated, since he can tolerate oral intake and has no high-risk features. Selected immunocompetent patients with mild uncomplicated disease may even be managed without antibiotics, but outpatient oral therapy remains standard. Hospitalization is reserved for patients with complicated disease, significant comorbidities, inability to tolerate oral intake, or clinical deterioration.

• A. Colonoscopy is contraindicated during acute diverticulitis due to perforation risk and should be deferred 6-8 weeks after resolution to exclude malignancy.
• B. Emergency surgery is indicated for complicated diverticulitis with perforation, peritonitis, or failure of medical therapy, not for this uncomplicated case.
• C. Hospital admission with intravenous antibiotics is reserved for complicated diverticulitis or patients unable to tolerate oral intake or with signs of systemic illness.
• E. Percutaneous drainage is used for diverticular abscesses larger than 3-4 cm, and no abscess is present on this CT.

The USPSTF recommends colorectal cancer screening beginning at age 45 years for average-risk adults, a change from the previous threshold of age 50 due to rising incidence of colorectal cancer in younger adults. Acceptable screening modalities include colonoscopy every 10 years, FIT or guaiac-based fecal occult blood testing annually, FIT-DNA (multitarget stool DNA test) every 1-3 years, or CT colonography every 5 years, among others, allowing patient choice based on preference and accessibility. Since this patient is 46 years old and average risk, screening should begin now rather than being deferred. The choice of modality should be individualized rather than restricted to a single test.

• A. Fecal immunochemical testing itself is a screening test; it is not used as a prerequisite trigger for starting routine screening.
• C. Flexible sigmoidoscopy alone is an acceptable but not exclusive option; multiple other modalities, including colonoscopy and stool-based tests, are equally valid first-line choices.
• D. The USPSTF lowered the average-risk screening start age to 45 years, so deferring to age 50 is outdated guidance.
• E. Screening for colorectal cancer is meant to detect disease before symptoms develop, so waiting for symptoms defeats the purpose of screening.

This patient's early-onset colorectal cancer, strong family history of colorectal and endometrial cancers at young ages, and tumor immunohistochemistry showing loss of MLH1/PMS2 expression with microsatellite instability are classic features of Lynch syndrome, a hereditary cancer syndrome caused by germline mutations in DNA mismatch repair genes (MLH1, MSH2, MSH6, PMS2). Confirmed or suspected Lynch syndrome warrants germline genetic testing and genetic counseling for the patient and cascade testing for at-risk relatives. Identified carriers require earlier and more frequent colonoscopic surveillance, typically starting at age 20-25 years and repeated every 1-2 years, along with surveillance for endometrial, ovarian, and other associated cancers.

• A. The combination of early-onset cancer, family history, and abnormal immunohistochemistry findings strongly suggests a hereditary syndrome rather than a coincidental cluster.
• B. Beginning screening at age 50 years reflects average-risk guidelines and is far too late for a hereditary cancer syndrome with young-onset disease.
• C. Lynch syndrome surveillance should begin proactively based on genetic risk, not reactively after additional relatives develop cancer.
• D. Lynch syndrome increases risk of colorectal and endometrial cancer in both sexes to varying degrees and is not addressed by mammography screening alone.

Iron deficiency anemia in a man older than 50 years, especially with a positive fecal occult blood test, must be evaluated for colorectal cancer as the most common and most dangerous explainable cause, regardless of the absence of overt gastrointestinal bleeding symptoms. Since upper endoscopy has already excluded an upper gastrointestinal source, colonoscopy is the appropriate next step to evaluate the lower gastrointestinal tract for malignancy, polyps, or angiodysplasia. Capsule endoscopy and CT enterography are reserved for evaluating the small bowel after both upper endoscopy and colonoscopy fail to identify a source. Simply treating with iron and observing risks missing an underlying malignancy that requires timely diagnosis and treatment.

• A. Small bowel capsule endoscopy is appropriate only after colonoscopy and upper endoscopy fail to identify a bleeding source.
• B. Upper endoscopy has already been performed and was unremarkable, so repeating it is not the appropriate next step.
• C. CT enterography evaluates the small bowel and is used only after standard upper and lower endoscopic evaluation is unrevealing.
• D. Empirical iron therapy without further workup risks delaying diagnosis of an underlying colorectal malignancy in this high-risk age group.