Cholecystocentesis is the aspiration sampling of gallbladder bile; this can be completed using a percutaneous transhepatic ultrasound-guided approach, by laparoscopic assistance, or during exploratory abdominal surgery. Samples of bile are collected for cytologic investigation and culture of aerobic and anaerobic bacteria and fungi; collection of bile that contains particulate debris or sediment has the highest yield to find microorganisms (cytologically, by culture). Complications of cholecystocentesis may include intraperitoneal bile leakage (reduced by using a transhepatic approach), hemorrhage, hemobilia, bacteremia, and vasovagal reaction, especially in cats, that may result in ventilatory arrest, severe bradycardia, and death. If a gallbladder mucocele or EHBDO is suspected, cholecystocentesis is contraindicated. It is better to perform a cholecystectomy for gallbladder mucocele and surgically decompress EHBDO (relieve or bypass the obstruction).