Spontaneous passage of common bile duct stones after magnetic resonance imaging

Endoscopic retrograde cholangiopancreatography (ERCP) is the standard treatment for common bile duct stones (CBDS) but carries risks. Stones may pass spontaneously to the duodenum before ERCP. This retrospective study aimed to identify factors associated with the absence of CBDS in ERCP to reduce unnecessary procedures and improve patient safety.

We analyzed 481 patients with CBDS verified by magnetic resonance cholangiopancreatography (MRCP) who underwent ERCP at hospitals within the Helsinki University Hospital district between January 2020 and May 2024. Data on patients' medical history, clinical, laboratory, radiographic and endoscopic findings were retrieved from electronic medical records.

Of the 481 patients, 97.9% were admitted to the emergency department due to acute symptoms. After diagnosis of CBDS based on MRCP findings, 121 (25.2%) patients had no stones at ERCP. Logistic regression identified predictors of spontaneous stone passage: acute pancreatitis (OR 2.987, 95% CI 1.813-4.921, p < 0.001), smaller stone size in millimeters (OR 0.818, 95% CI 0.738-0.906, p < 0.001), distal stone location (OR 2.255, 95% CI 1.295-3.928, p = 0.004), single CBDS (OR 1.975, 95% CI 1.092-3.573, p = 0.024) and longer interval in hours between MRCP and ERCP (OR 1.009, 95% CI 1.004-1.014, p < 0.001). During follow-up, a greater decrease in alanine aminotransferase (ALT) was the only laboratory parameter associated with spontaneous stone passage.

One in four ERCPs for CBDS may be unnecessary. Our findings suggest that acute pancreatitis, several features in MRCP and timing from MRCP to ERCP may be used as predictors to select patients with CBDS to wait-and-see policy instead of urgent ERCP.