A 58-year-old man presents with painless progressive jaundice for 3 weeks. He has lost 5 kg in weight over 2 months. On examination, Courvoisier's sign is positive. Serum bilirubin is 8.2 mg/dL (direct 6.8), alkaline phosphatase 420 IU/L, and transaminases are mildly elevated. Abdominal ultrasound shows dilated intrahepatic bile ducts, a dilated common bile duct (12 mm), and a hypoechoic lesion in the pancreatic head. What is the most appropriate next investigation to confirm the diagnosis and guide surgical planning?

Explanation

## Clinical Scenario Analysis This is a classic presentation of **pancreatic head carcinoma** with obstructive jaundice: - Painless jaundice (Courvoisier's sign positive) - Weight loss (constitutional symptom of malignancy) - Dilated CBD with pancreatic head lesion on ultrasound ## Why CT Abdomen with Pancreatic Protocol is Correct **Key Point:** CT with pancreatic protocol (thin-slice, dual-phase imaging with arterial and portal venous phases) is the **gold standard for staging pancreatic cancer** and surgical planning. **High-Yield:** CT provides: 1. **Tumor characterization** — size, location, local extension 2. **Resectability assessment** — vascular involvement (superior mesenteric artery, portal vein, hepatic artery) 3. **Metastatic staging** — liver, peritoneal, distant nodes 4. **Surgical planning** — determines candidacy for Whipple's pancreaticoduodenectomy vs. palliative bypass **Clinical Pearl:** In obstructive jaundice with suspected malignancy, imaging must answer: *Is this resectable?* CT is superior to ultrasound for this assessment because it evaluates vascular involvement and distant spread. ## Comparison of Diagnostic Modalities | Modality | Role | Limitation | |----------|------|----------| | **CT pancreatic protocol** | Staging, resectability, surgical planning | Gold standard for pancreatic cancer workup | | **MRCP** | Biliary anatomy, benign obstruction | Does not stage malignancy, poor for vascular involvement | | **ERCP** | Therapeutic (stent placement), tissue diagnosis | Invasive; reserved for therapy or when CT inconclusive; risk of pancreatitis | | **PTC** | Palliative drainage in unresectable disease | Not first-line diagnostic; invasive; for drainage only | ## Surgical Workup Algorithm ```mermaid flowchart TD A[Obstructive jaundice + weight loss + Courvoisier sign]:::outcome --> B{Ultrasound shows pancreatic lesion?}:::decision B -->|Yes| C[CT abdomen with pancreatic protocol]:::action C --> D{Resectable?}:::decision D -->|Yes| E[Whipple pancreaticoduodenectomy]:::action D -->|No| F[ERCP + stent for palliative drainage]:::action B -->|No, benign obstruction| G[MRCP or ERCP for therapy]:::action ``` **Mnemonic:** **CREST** for pancreatic cancer workup: - **C**T (pancreatic protocol) - **R**esectability assessment - **E**xtension to vessels - **S**taging (metastases) - **T**herapy planning [cite:Sabiston Textbook of Surgery Ch 57]