A 58-year-old man presents with painless progressive jaundice for 3 weeks, pale stools, and dark urine. On examination, Courvoisier's sign is positive. Serum bilirubin is 8.2 mg/dL (direct 6.8 mg/dL), ALP 420 IU/L, and GGT elevated. Abdominal ultrasound shows dilated intrahepatic and extrahepatic bile ducts with a hypoechoic lesion in the pancreatic head. What is the investigation of choice to confirm the diagnosis and guide surgical planning?

Explanation

## Investigation of Choice for Obstructive Jaundice with Suspected Pancreatic Malignancy ### Clinical Context This patient presents with classic features of **pancreatic head carcinoma**: - Painless progressive jaundice (Courvoisier's sign positive) - Dilated intrahepatic and extrahepatic bile ducts on ultrasound - Hypoechoic lesion in pancreatic head - Elevated liver enzymes (ALP, GGT) indicating biliary obstruction ### Why CECT Abdomen and Pelvis is the Investigation of Choice **Key Point:** CECT is the gold standard for staging pancreatic malignancy and determining resectability before any intervention. 1. **Tissue characterization**: Differentiates pancreatic mass from chronic pancreatitis 2. **Tumor staging**: Assesses local invasion, vascular involvement (superior mesenteric artery/vein, portal vein), and distant metastases 3. **Resectability assessment**: Critical for surgical planning — determines whether the patient is a candidate for curative resection (Whipple's procedure) 4. **Simultaneous evaluation**: Visualizes liver, peritoneum, and regional lymph nodes in one study 5. **No therapeutic delay**: Unlike ERCP (which is therapeutic but delays definitive surgery), CECT provides diagnostic information immediately ### Comparison of Imaging Modalities | Investigation | Role | Timing | Limitation | | --- | --- | --- | --- | | **CECT** | Staging, resectability, tissue characterization | First-line imaging | Radiation exposure | | **MRCP** | Ductal anatomy, choledocholithiasis | When ERCP contraindicated | Poor tissue characterization, longer acquisition | | **ERCP** | Therapeutic drainage (stent placement) | After resectability confirmed | Invasive, risk of pancreatitis, delays surgery | | **PTC** | Biliary drainage when ERCP fails | Salvage option | Invasive, percutaneous approach, higher morbidity | ### Clinical Pearl **High-Yield:** In obstructive jaundice with suspected malignancy, **CECT for staging precedes ERCP for drainage**. ERCP should be reserved for therapeutic intervention (biliary stent) in unresectable cases or preoperative drainage if surgery is delayed. Immediate ERCP in a resectable patient risks infection and delays definitive surgical treatment. ### Surgical Workflow 1. CECT → assess resectability 2. If resectable → proceed to surgery (Whipple's pancreaticoduodenectomy) 3. If unresectable/metastatic → ERCP + stent for palliative drainage 4. If ERCP fails → PTC for drainage **Mnemonic: CECT First, ERCP Last (in malignancy)** — CECT for staging and surgical planning; ERCP only when surgery is not an option.