An adult without prior medical conditions presents with 12 hours of upper abdominal pain and nausea (no vomiting), normal vital signs, normal sclera and skin, tender deep abdominal palpation, and ultrasound showing multiple gallstones, normal gallbladder wall thickness, no pericholecystic fluid, and a common bile duct stone causing obstruction. Which diagnosis is most likely: pancreatitis, cholecystitis, obstructive jaundice, or small‑bowel obstruction?

Most Likely Diagnosis: Obstructive Jaundice (Choledocholithiasis)

The correct answer is C: Obstructive jaundice. The ultrasound finding of a common bile duct stone causing obstruction is diagnostic of choledocholithiasis, which by definition constitutes obstructive jaundice regardless of whether clinical jaundice is yet visible. 1

Why Obstructive Jaundice is the Diagnosis

Imaging Findings Are Definitive

• A stone within the common bile duct confirmed on ultrasound is diagnostic of choledocholithiasis, which is the most common cause of obstructive jaundice even when visible jaundice has not yet appeared. 1
• The American College of Radiology considers ultrasound demonstration of CBD obstruction by stone to be definitive for this diagnosis. 1

The Critical Timing Issue: Jaundice Takes 24-48 Hours to Appear

• Serum bilirubin must reach approximately 2.5–3 mg/dL before scleral icterus becomes clinically detectable, a process that typically requires 24–48 hours after acute biliary obstruction begins. 1
• This patient presents at only 12 hours, which is too early for visible jaundice to manifest despite having complete CBD obstruction. 1
• Clinicians must not postpone the diagnosis of obstructive jaundice while awaiting visible jaundice—imaging confirmation of CBD obstruction is sufficient. 1

Why the Other Options Are Incorrect

B. Cholecystitis is excluded by imaging:

• The absence of gallbladder wall thickening and pericholecystic fluid effectively rules out acute cholecystitis, with these sonographic findings having a 95–96% negative predictive value. 1
• Normal gallbladder wall thickness on ultrasound makes cholecystitis highly unlikely. 1

A. Pancreatitis is less likely based on clinical presentation:

• While CBD stones can cause pancreatitis 2, 3, 4, the clinical pattern of upper abdominal pain with nausea but no vomiting aligns more closely with biliary obstruction than acute pancreatitis. 1
• Pancreatitis typically presents with more severe pain, often radiating to the back, and more prominent vomiting.

D. Small bowel obstruction is not supported:

• There are no changes in bowel habits, no vomiting, and normal vital signs—all inconsistent with bowel obstruction.
• The ultrasound findings point directly to biliary pathology, not intestinal obstruction.

Clinical Implications and Urgent Management

This Diagnosis Requires Prompt Intervention

• Untreated CBD stones progress to overt jaundice, cholangitis, and potentially life-threatening complications including hepatic abscesses, pancreatitis, and secondary biliary cirrhosis. 2, 1
• Urgent stone extraction is advised to prevent these complications. 1

Treatment Approach

• ERCP with sphincterotomy and stone removal achieves approximately 90% success rate and is the primary treatment modality. 1
• Even small stones (<4 mm) should be actively treated: active management results in 8.9% unfavorable outcomes versus 15.9% with conservative observation. 1
• In the GallRiks study, 25.3% of patients with CBD stones left in situ experienced unfavorable outcomes (pancreatitis, cholangitis, or obstruction) compared to only 12.7% who underwent planned stone extraction. 2

Key Clinical Pitfall to Avoid

The absence of visible jaundice does NOT exclude obstructive jaundice. The diagnosis is made by imaging demonstration of CBD obstruction, not by waiting for clinical signs that may take 1–2 days to develop. 1 This patient has anatomic obstruction confirmed on ultrasound—that is sufficient to establish the diagnosis and initiate urgent treatment planning.