What is the most likely diagnosis for an elderly patient with confusion, epigastric discomfort, abnormal liver function tests, raised CRP, gallstones, and a mildly dilated common bile duct?

Most Likely Diagnosis: Cholangitis

The most likely diagnosis is cholangitis (Option B), given the combination of confusion (sepsis-related), markedly elevated inflammatory markers (CRP 120 mg/L), obstructive liver function test pattern (bilirubin 120 μmol/L, ALP 750 IU/L), and dilated common bile duct in an elderly patient with gallstones.

Clinical Reasoning

Key Diagnostic Features Supporting Cholangitis

• Confusion in an elderly patient with elevated CRP (120 mg/L) strongly suggests systemic infection/sepsis, which is the hallmark of cholangitis rather than simple cholecystitis 1

• The obstructive pattern of liver enzymes is critical: bilirubin of 120 μmol/L (approximately 7 mg/dL) with ALP 750 IU/L indicates biliary obstruction with infection 1

• Dilated common bile duct without visible stones on ultrasound does not exclude cholangitis—ultrasound has only 73% sensitivity for detecting common bile duct stones, and stones may have passed or be intermittently obstructing 1

Risk Stratification for Common Bile Duct Stones

According to the modified ASGE criteria, this patient falls into the high-risk category for choledocholithiasis based on:

• Bilirubin > 4 mg/dL (approximately 68 μmol/L) - this patient has 120 μmol/L (approximately 7 mg/dL) 1, 2
• Dilated common bile duct on ultrasound 1
• Clinical picture consistent with ascending cholangitis (confusion, elevated inflammatory markers) 1, 3

High-risk patients have a >50% probability of having common bile duct stones and should proceed directly to therapeutic ERCP 1, 3

Why Not the Other Options?

Cholecystitis (Option C) - Less Likely

• Cholecystitis typically presents with right upper quadrant pain and fever, not confusion 1
• The degree of hyperbilirubinemia (120 μmol/L) is excessive for simple cholecystitis—cholecystitis usually causes mild bilirubin elevation if any 1
• CRP of 120 mg/L with confusion suggests systemic sepsis from biliary infection (cholangitis) rather than localized gallbladder inflammation 1

Ampullary Carcinoma (Option A) - Unlikely

• Malignant obstruction typically presents with painless progressive jaundice, not acute confusion with high inflammatory markers 1
• The presence of gallstones makes a calculous etiology far more likely in this acute presentation 4

Pancreatic Carcinoma (Option D) - Unlikely

• Similar to ampullary carcinoma, pancreatic cancer presents with painless jaundice and weight loss, not acute septic picture 1
• CRP of 120 mg/L is inconsistent with malignant obstruction 1

Primary Sclerosing Cholangitis (Option E) - Unlikely

• PSC is a chronic progressive disease diagnosed by MRCP showing characteristic beading and strictures of bile ducts 1, 5, 6
• PSC typically presents with chronic elevation of ALP discovered on routine screening, not acute confusion and sepsis 1, 7
• PSC is strongly associated with inflammatory bowel disease (71% of cases), which is not mentioned in this patient 7, 8

Immediate Management Approach

This patient requires urgent intervention for suspected cholangitis:

• Initiate broad-spectrum antibiotics immediately for ascending cholangitis 2
• Proceed directly to ERCP given high-risk criteria (bilirubin >4 mg/dL and dilated CBD) without need for additional imaging 1, 2
• Blood cultures should be obtained before antibiotics 2

Common Pitfall to Avoid

Do not delay ERCP to obtain MRCP or EUS in high-risk patients—the 2020 World Society of Emergency Surgery guidelines emphasize that patients meeting high-risk criteria (visible CBD stone on ultrasound OR bilirubin >4 mg/dL with dilated CBD) should proceed directly to therapeutic ERCP 1. Additional imaging only delays definitive treatment and increases morbidity in septic patients 1.