This study evaluates the long-term safety and efficacy of the Hong Kong follow up protocol in patients who will undergo drainage of the gallbladder under endoultrasonography (EUS) guidance in patients with acute cholecistitis not suitable for surgery.

Acute cholecystitis is a common surgical condition. However, in elderly patients or patients with significant comorbidity, emergency laparoscopic cholecystectomy can be associated with significant risk of morbidities. Thus, in these patients, percutaneous cholecystostomy (PC) could be employed for drainage of the gallbladder. However, complications including intrahepatic hemorrhage, pneumothorax, biliary peritonitis and pneumonia have been reported in a mean of 6.2% of patients (range 0-25%). Furthermore, PC has several other disadvantages including risk of bile leakage, recurrent cholecystitis, inadvertent tube removal and migration (0-25%), necessitating repeated procedures. In order to avoid nuisances associated with PC, studies looking at potential ways to achieve endoscopic gallbladder drainage have been performed. On the other hand, EUS-guided transmural drainage procedures are increasingly performed for management of a variety of conditions and has also been described for drainage of the gallbladder in patients that are not fit for surgery since 2007. Recently, a lumen-apposing metal stent (LAMS) has become available which allows easier deployement of the stent. A 9.8mm gastroscope or a 5mm ultrathin nasal endoscope can pass through the lumen of the stent and enter the gallbladder for stone removal or other interventions A recent study group from Hong Kong promoted a specific follow up for EUS guided gallbaldder drainage patients who underwent a follow-up cholecystoscopy after the procedure to check for clearance of stones. In patients with stones that were too large to pass out spontaneously, basket mechanical lithotripsy was employed to break down the stones, followed by laser lithotripsy if the latter was not successful. No data on the safety and efficacy of the Hong Kong follow up protocol in patients who underwent EGBD using LAMS coming from countries other than Asian are available, in which differences in etiological and pathogenic factors might not required such an intensive follow up protocol. To explore this important question we have designed a study aimed at evaluating the long-term safety and efficacy of the Hong Kong follow up protocol in patients undergoing EGBD performed using LAMS.

Inclusion Criteria:

• Consecutive patients with acute cholechystitis unsuitable for surgery
• age ≥ 18 years old
• Written informed consent from patient or guardian who is able to understand the nature and possible consequences of the study

Exclusion Criteria:

• Pregnancy
• Patients unwilling to undergo follow-up assessments
• Patients with suspected gangrene or perforation of the gallbladder
• Patients diagnosed with concomitant liver abscess or pancreatitis (defined as elevated serum amylase more than three times the upper limit of normal)
• Altered anatomy of the upper gastrointestinal tract due to surgery of the esophagus, stomach and duodenum
• Patients with liver cirrhosis, portal hypertension and/or gastric varices
• Abnormal coagulation (INR > 1.5 and/or platelets < 50.000/mm3)
• Contraindication to perform endoscopy

This study concerns consecutive patients undergoing EGBD using LAMS as per decision of the on call surgeons of the Emergency Surgery Department with diagnosis of acute cholecystitis, who are unsuitable for early laparoscopic cholecystectomy due to poor premorbid conditions