A 58-year-old man presents with progressive jaundice, pale stools, and dark urine for 3 weeks. Clinical examination reveals a palpable gallbladder and hepatomegaly. Serum bilirubin is 8.2 mg/dL (predominantly direct), ALP 320 U/L, and ALT 95 U/L. Abdominal ultrasound shows dilated intrahepatic and extrahepatic bile ducts with a hypoechoic lesion in the pancreatic head. Which investigation is most appropriate for definitive diagnosis and staging before planning surgical intervention?

Explanation

## Investigation of Choice: Contrast-Enhanced CT Abdomen **Key Point:** In obstructive jaundice with suspected pancreatic malignancy, contrast-enhanced CT (CECT) is the first-line imaging modality for diagnosis, staging, and surgical planning. ### Why CECT is Superior in This Context | Feature | CECT | ERCP | PTC | HIDA | |---------|------|------|-----|------| | **Tissue diagnosis** | No | Yes, but invasive | No | No | | **Staging (resectability)** | Excellent | Poor | Poor | None | | **Vascular involvement** | Clear | Not visible | Not visible | None | | **Metastases** | Detected | Not assessed | Not assessed | Not assessed | | **Morbidity** | Minimal | 3–5% pancreatitis | 5–10% cholangitis | None | | **Timing** | First-line | After imaging | Rescue option | Rarely used | **High-Yield:** CECT provides: 1. **Tumor characterization** — size, location, density enhancement pattern 2. **Resectability assessment** — vascular involvement (portal vein, superior mesenteric vessels) 3. **Staging** — liver metastases, peritoneal disease, distant nodes 4. **Surgical planning** — determines candidacy for curative resection vs. palliative bypass ### Clinical Pearl **Warning:** ERCP should NOT be the first investigation in suspected malignant obstruction. ERCP is reserved for: - Therapeutic intervention (stent placement) after diagnosis is confirmed - Tissue sampling only if CT findings are equivocal and diagnosis is uncertain - Benign obstruction (stones, strictures) Performing ERCP before staging risks: - Pancreatitis (3–5% incidence, delays surgery) - Incomplete staging if malignancy is discovered - Stent-related complications ### Algorithm: Obstructive Jaundice Workup ```mermaid flowchart TD A[Obstructive jaundice + dilated ducts on US]:::outcome --> B{Clinical suspicion of malignancy?}:::decision B -->|Yes| C[CECT abdomen/pelvis]:::action B -->|No| D[CECT or MRCP]:::action C --> E{Resectable?}:::decision E -->|Yes| F[Proceed to surgery]:::action E -->|No| G[ERCP + stent for palliation]:::action D --> H{Diagnosis confirmed?}:::decision H -->|Yes| I[Manage accordingly]:::action H -->|No| J[ERCP ± tissue sampling]:::action ``` **Mnemonic: CECT-FIRST** — **C**ontrast-enhanced **C**T is **F**irst for **I**maging **R**esectability, **S**taging, and **T**umor characterization. [cite:Sabiston Textbook of Surgery Ch 54]