Prospective Comparison of Endoscopic Ultrasonography and Magnetic Resonance Cholangiopancreatography in the Etiological Diagnosis of "Idiopathic" Acute Pancreatitis

Objectives: The objectives of the study were to compare endoscopic ultrasonography (EUS) and magnetic resonance cholangiopancreatography (MRCP) in the etiological diagnosis of patients initially diagnosed with idiopathic acute pancreatitis and to determine the clinical and analytical factors related to the end result of these techniques. Methods: Forty-nine patients, initially diagnosed with idiopathic acute pancreatitis, were evaluated prospectively with EUS and MRCP. Diagnoses were compared between the 2 procedures. The clinical-evolutionary characteristics of these patients with regard to the results obtained with these techniques were compared. Results: In twenty-eight patients (57%), EUS and/or MRCP diagnosed at least 1 possible cause of acute pancreatitis. The diagnostic yield of EUS was higher than that of MRCP (51% vs 20%; P = 0.001). Cholelithiasis and biliary sludge (24%) were the most frequent EUS diagnoses, and pancreas divisum (8%) was the most frequent MRCP diagnosis. Only in 3 cases (6%) did MRCP identify additional features in patients etiologically undiagnosed using EUS. The EUS yield was lower in patients who had a previous cholecystectomy (11% vs 60%; P = 0.008). Conclusions: Endoscopic ultrasonography and MRCP are useful techniques in the etiological diagnosis of acute pancreatitis of non-established cause. Endoscopic ultrasonography should be preferred for establishing a possible biliary etiology in patients who have not had a cholecystectomy.