A 58-year-old man presents with painless jaundice, pale stools, and dark urine for 3 weeks. Abdominal examination reveals a palpable gallbladder. Laboratory investigations show conjugated hyperbilirubinemia and elevated alkaline phosphatase. Regarding the diagnostic workup for obstructive jaundice, all of the following are appropriate initial investigations EXCEPT:

Explanation

## Diagnostic Approach to Obstructive Jaundice ### Appropriate Initial Investigations **Key Point:** The workup for obstructive jaundice follows a stepwise approach: clinical assessment → laboratory confirmation → imaging → endoscopic/percutaneous intervention only when diagnosis is confirmed and therapeutic intervention is needed. | Investigation | Role | Timing | |---|---|---| | Liver function tests | Confirm cholestasis pattern (↑ ALP, GGT, conjugated bilirubin) | First-line | | Abdominal ultrasound | Detect biliary dilatation, gallstones, pancreatic mass | First-line imaging | | Serum amylase/lipase | Rule out pancreatitis as obstruction cause | First-line | | CT abdomen/pelvis | Characterize pancreatic/biliary lesion, assess resectability | Second-line imaging | | MRCP | Non-invasive cholangiography if diagnosis unclear | Second-line | | ERCP | Therapeutic intervention (sphincterotomy, stent) | Only after diagnosis confirmed | ### Why ERCP Is NOT First-Line Diagnostic Tool **High-Yield:** ERCP is an **invasive procedure with significant morbidity** (pancreatitis 3–5%, perforation, bleeding). It is reserved for **therapeutic intervention** in confirmed biliary obstruction, not for initial diagnosis. **Clinical Pearl:** The classic teaching is: "Diagnose with imaging (ultrasound/MRCP), treat with ERCP." Using ERCP as a first-line diagnostic tool exposes patients to unnecessary procedural risk when non-invasive imaging (ultrasound, MRCP) can establish the diagnosis. ### Correct Diagnostic Sequence 1. **Clinical assessment** → painless jaundice + palpable gallbladder (Courvoisier's sign) suggests pancreatic head mass or distal CBD obstruction 2. **LFTs** → confirm cholestasis (elevated ALP, GGT, conjugated bilirubin) 3. **Ultrasound** → detect biliary dilatation, assess pancreatic head 4. **Serum amylase/lipase** → exclude pancreatitis as the cause 5. **CT or MRCP** → characterize lesion (stone vs. malignancy) 6. **ERCP** → only if therapeutic intervention (sphincterotomy for stone, stent for stricture/malignancy) is planned **Warning:** Performing ERCP before confirming the diagnosis and establishing the need for intervention increases morbidity without diagnostic benefit. [cite:Sabiston Textbook of Surgery 21e Ch 54]