Comparing Endoscopic Ultrasound (EUS) vs. Magnetic Resonance Cholangiopancreatography (MRCP) in the Etiological Evaluation of Idiopathic Acute Pancreatitis (IAP): A Systematic Review and Meta-Analysis.

Introduction: Idiopathic acute pancreatitis (IAP) accounts for up to 20% of acute pancreatitis cases despite thorough initial evaluation. Endoscopic ultrasound (EUS) and magnetic resonance cholangiopancreatography (MRCP) are commonly used as second-line imaging modalities when IAP etiologies are unclear, yet their comparative diagnostic performance remains uncertain. We conducted a systematic review and meta-analysis to assess the diagnostic yield of EUS versus MRCP in identifying etiologies of IAP.

Methods: A systematic search of PubMed, EMBASE, and Google Scholar (January 2000-April 2025) identified English-language studies comparing EUS and MRCP diagnostic performance in IAP. Two reviewers independently extracted data and assessed study quality using the Newcastle-Ottawa Scale. Pooled relative risks (RR) were calculated using a random-effects model, with subgroup, sensitivity, and publication bias analyses done per PRISMA 2020. Subgroup analyses assessed diagnostic yield by etiology-biliary disease (cholelithiasis, choledocholithiasis, microlithiasis, and sludge), pancreatic divisum, intraductal papillary mucinous neoplasm (IPMN), and malignancy (pancreatic adenocarcinoma and periampullary cancer).

Results: Of 4,933 studies screened, 8 met inclusion criteria. Pooled analysis showed that EUS had significantly higher diagnostic yield than MRCP (RR 2.01; 95% CI 1.42-2.85; p < 0.01; I² = 69.1%). EUS was markedly superior for biliary etiologies (RR 3.67; 95% CI 2.08-6.47; p < 0.0001; I² = 37.7%) and trended toward better detection of CP in IAP (RR 2.20; 95% CI 0.87-5.55; p = 0.0955; I² = 15.5%). MRCP favored the detection of pancreatic divisum (RR 0.59; 95% CI 0.31-1.12; p = 0.1078; I² = 0.0%). Both EUS and MRCP performed equally in detecting IPMNs (RR 0.88; 95% CI 0.35-2.22; p = 0.7861; I² = 0.0%). EUS also demonstrated higher cancer detection compared to MRCP (RR 1.98; 95% CI 0.56-7.03; p = 0.2896; I² = 0.0%).

Conclusion: EUS surpasses MRCP in diagnosing IAP biliary etiologies and has an overall higher diagnostic yield. Prior studies suggest that EUS may be oversensitive in diagnosing CP, which may be consistent with the increased rate of diagnosis by EUS in our data. There was some signal that EUS had a higher diagnostic yield for cancer, which may highlight a potential role in identifying occult malignancy in IAP evaluation. In practice, choosing EUS vs. MRCP depends on resource availability, but a patient-centered approach that integrates modality strengths with clinical profiles can improve diagnostic accuracy and prognostic outcomes.