Biliopleural Fistula Following Percutaneous Transhepatic Drainage: A Rare Cause of Bilious Pleural Effusion.

Biliopleural fistula is a rare but serious complication of hepatobiliary interventions. It may present with atypical respiratory symptoms and requires a high index of suspicion for diagnosis. We report the case of a 79‑year‑old woman with choledocholithiasis complicated by failed endoscopic retrograde cholangiopancreatography (ERCP), post‑ERCP pancreatitis, and cholangitis. Following percutaneous transhepatic drainage (PTD) with external biliary catheter placement, she developed a loculated right‑sided pleural effusion. Diagnostic thoracentesis revealed bilious pleural fluid, and magnetic resonance cholangiopancreatography (MRCP) confirmed a fistulous tract between the intrahepatic biliary system and the pleural space. Surgical thoracotomy with decortication established the diagnosis and resolved the condition. This case highlights the importance of recognizing biliopleural fistula as a potential complication of PTD. Early imaging and timely surgical intervention are critical to prevent respiratory compromise.