A 38-year-old woman presents to the emergency department with acute onset epigastric pain radiating to the back, associated with nausea and vomiting for 6 hours. She has a history of gallstones. On examination, she is febrile (38.5°C) with epigastric tenderness. Serum amylase is elevated at 450 U/L (normal <100). What is the investigation of choice to confirm acute pancreatitis and assess severity?

Explanation

## Investigation of Choice in Acute Pancreatitis **Key Point:** While serum lipase is the biochemical marker of choice for diagnosis, CECT abdomen is the imaging investigation of choice for confirming acute pancreatitis and assessing disease severity, complications, and prognosis. ### Role of CECT Abdomen **High-Yield:** CECT is the gold standard imaging modality because it: 1. Confirms the diagnosis of acute pancreatitis (pancreatic edema, inflammation) 2. Assesses severity using the Modified Marshall Score and Balthazar grading 3. Detects complications (necrosis, fluid collections, pseudocysts, organ failure) 4. Identifies the etiology (gallstones, ductal obstruction) 5. Guides management decisions and prognostication ### Timing of CECT **Clinical Pearl:** CECT is ideally performed after 48–72 hours from symptom onset when pancreatic inflammation is fully established. Early CECT (<48 hours) may underestimate necrosis and severity. ### Comparison of Investigations | Investigation | Role | Limitations | |---|---|---| | **Serum lipase** | Biochemical diagnosis (3× upper limit normal) | Does not assess severity or complications | | **Serum amylase** | Diagnostic aid; less specific than lipase | Normalizes quickly; not useful after 48 hrs | | **Abdominal ultrasound** | Detects gallstones, biliary obstruction | Poor visualization of pancreas; operator-dependent | | **MRCP** | Identifies biliary/ductal pathology | Not first-line for severity assessment; reserved for suspected biliary pancreatitis with cholangitis | | **CECT abdomen** | **Gold standard for imaging** | Confirms diagnosis, assesses severity, detects necrosis and complications | **Warning:** Do not confuse the biochemical marker of choice (serum lipase) with the imaging investigation of choice (CECT). The question asks for investigation of choice in the clinical context of a patient with suspected acute pancreatitis — this requires imaging confirmation and severity assessment. ### Balthazar Score (CECT Grading) - **Grade A:** Normal pancreas - **Grade B:** Pancreatic enlargement only - **Grade C:** Pancreatic changes + peripancreatic fat stranding - **Grade D:** Grade C + single fluid collection - **Grade E:** Grade C + two or more fluid collections **Mnemonic:** ABCDE = **A**ll **B**ody **C**hange **D**evelops **E**ventually (progressing severity) [cite:Harrison 21e Ch 346]