Gallbladder Agenesis and a Large Common Bile Duct Stone: A Case Report and Literature Review.

Gallbladder agenesis is a rare congenital anomaly that is often asymptomatic but may present with clinical features mimicking biliary tract disease. The absence of the gallbladder is frequently undetected by abdominal ultrasound, leading to diagnostic uncertainty and potential surgical dilemmas. Accurate preoperative diagnosis is essential to avoid unnecessary surgical exploration and iatrogenic complications. We report a case of a 67-year-old male who presented with acute cholangitis secondary to choledocholithiasis. Cross-sectional imaging (CT and magnetic resonance cholangiopancreatography) revealed no identifiable gallbladder, while endoscopic retrograde cholangiopancreatography was inconclusive due to the presence of a large common bile duct stone. Laparoscopic exploration of the biliary tract was performed, resulting in the extraction of a 20 mm stone and intraoperative confirmation of gallbladder agenesis. This case emphasizes the importance of considering gallbladder agenesis in the differential diagnosis of biliary symptoms and highlights the need for comprehensive imaging to guide appropriate management and avoid unnecessary surgical risk.