In an otherwise healthy adult with 12 hours of upper abdominal pain, nausea, normal vitals, normal sclera and skin, and ultrasound showing multiple gallstones, a normal gallbladder wall, no pericholecystic fluid, and a common bile duct stone, what is the most likely diagnosis: pancreatitis, acute cholecystitis, obstructive jaundice, or small‑bowel obstruction?

Choledocholithiasis (Common Bile Duct Stone)

The most likely diagnosis is C. Obstructive jaundice, specifically choledocholithiasis (common bile duct stone obstruction), even though clinical jaundice is not yet apparent at 12 hours. 1

Diagnostic Reasoning

The ultrasound findings are definitive and drive the diagnosis:

• A stone obstructing the common bile duct is documented on imaging 1
• The absence of gallbladder wall thickening and pericholecystic fluid effectively rules out acute cholecystitis 1
• Normal gallbladder wall thickness has high negative predictive value (95-96%) for cholecystitis 1

Why Not the Other Options?

Acute Cholecystitis (Option B) - Excluded

• Acute cholecystitis requires gallbladder wall thickening, pericholecystic fluid, or Murphy's sign—none are present here 1
• The ultrasound specifically shows normal gallbladder wall thickness, which argues strongly against cholecystitis 1
• While gallstones are present, they alone do not constitute cholecystitis without inflammatory changes 1

Pancreatitis (Option A) - Less Likely

• Although CBD stones cause 10-20% of acute pancreatitis cases, this patient lacks the severe epigastric pain radiating to the back, vomiting, and elevated lipase/amylase typical of pancreatitis 2, 3, 4
• The clinical presentation of upper abdominal pain with nausea but no vomiting is more consistent with biliary obstruction 1

Small Bowel Obstruction (Option D) - Not Supported

• No bowel habit changes, no distension, and normal vital signs exclude this diagnosis 5
• Gallstone ileus (bowel obstruction from a migrated stone) would require a cholecystoenteric fistula and typically presents with complete obstruction symptoms 5, 4

The Jaundice Paradox

The absence of visible jaundice at 12 hours does not exclude obstructive jaundice as the diagnosis:

• Bilirubin must rise to approximately 2.5-3 mg/dL before scleral icterus becomes clinically apparent, which typically takes 24-48 hours after acute obstruction 6
• CBD obstruction by a stone is documented on ultrasound—this IS obstructive jaundice by definition, regardless of whether clinical jaundice is visible yet 1
• The natural history of untreated CBD stones includes progression to clinical jaundice, cholangitis, and potentially life-threatening complications 1, 3

Clinical Implications

This patient requires urgent intervention:

• CBD stones should be extracted if possible, as complications (cholangitis, pancreatitis, secondary biliary cirrhosis) can occur without warning 1
• Endoscopic retrograde cholangiopancreatography (ERCP) with sphincterotomy and stone extraction has a 90% success rate and is the mainstay of therapy 1, 2
• Even small CBD stones (<4 mm) benefit from active treatment, with lower unfavorable outcomes (8.9%) compared to conservative management (15.9%) 1

Critical Pitfall

Do not wait for clinical jaundice to develop before diagnosing obstructive jaundice when imaging confirms CBD obstruction—the diagnosis is anatomic, not purely clinical. 1, 6