Acute cholecystitis is a common indication for emergency laparoscopic cholecystectomy. Inflammatory changes and distorted anatomy may increase the risk of biliary complications, including bile duct injury and bile leak, which are associated with significant morbidity, reinterventions, and prolonged hospitalization. Indocyanine green (ICG) fluorescence cholangiography allows real-time visualization of the extrahepatic biliary anatomy using near-infrared imaging and has shown to improve anatomical identification during elective cholecystectomy. However, its clinical impact in the emergency setting of acute cholecystitis has not been adequately evaluated in randomized multicenter trials.

The objective of this study is to determine whether the use of ICG fluorescence cholangiography during emergency laparoscopic cholecystectomy reduces the incidence of clinically relevant biliary complications compared with standard surgery without ICG.

This is a pragmatic, multicenter, open-label randomized controlled trial including 296 adult patients with acute cholecystitis undergoing urgent laparoscopic cholecystectomy. Participants will be randomized 1:1 to surgery with or without ICG fluorescence guidance. The primary outcome is the incidence of clinically relevant biliary complications, including bile duct injury or bile leak, within 90 days after surgery.

Acute cholecystitis is one of the most common indications for emergency abdominal surgery. Early laparoscopic cholecystectomy is considered the standard treatment; however, inflammation and distorted anatomy may make identification of the biliary structures challenging, increasing the risk of bile duct injury or bile leak. These complications are associated with significant morbidity, need for additional procedures, prolonged hospitalization, and increased healthcare costs.

Indocyanine green (ICG) fluorescence cholangiography is an intraoperative imaging technique that allows real-time visualization of the extrahepatic biliary anatomy using near-infrared fluorescence. After intravenous administration, ICG is rapidly excreted into bile, enabling enhanced visualization of the biliary tree during laparoscopic surgery. Several studies in elective laparoscopic cholecystectomy have demonstrated that ICG fluorescence improves anatomical identification and may increase surgical safety. However, evidence regarding its effectiveness in the emergency setting of acute cholecystitis remains limited, and high-quality multicenter randomized controlled trials are lacking.

The ICG-ACBC Trial is designed to evaluate whether the systematic use of ICG fluorescence cholangiography during emergency laparoscopic cholecystectomy for acute cholecystitis reduces the incidence of clinically relevant biliary complications compared with standard laparoscopic cholecystectomy without fluorescence guidance.

This study is a multicenter, pragmatic, open-label randomized controlled trial. A total of 296 adult patients diagnosed with acute cholecystitis according to Tokyo Guidelines criteria and requiring urgent laparoscopic cholecystectomy will be enrolled across participating hospitals. Participants will be randomized in a 1:1 ratio to undergo surgery either with intraoperative ICG fluorescence guidance or with standard laparoscopic cholecystectomy without ICG. Randomization will be centralized and stratified by participating center.

In the intervention group, patients will receive an intravenous dose of indocyanine green prior to surgery, and near-infrared imaging will be used intraoperatively to visualize the biliary anatomy. In the control group, patients will undergo standard laparoscopic cholecystectomy following established surgical principles, including the critical view of safety.

The primary outcome is the incidence of clinically relevant biliary complications, defined as bile duct injury or clinically significant bile leak, occurring within 90 days after surgery. Secondary outcomes include other perioperative complications, conversion to open surgery, length of hospital stay, reinterventions, readmissions, surgeon-reported visualization quality, and patient-reported outcomes.

The results of this study may provide high-quality evidence on whether routine use of ICG fluorescence cholangiography improves surgical safety in emergency cholecystectomy for acute cholecystitis and may inform future clinical guidelines and surgical practice.

Inclusion Criteria:

• Age ≥ 18 years.
• Diagnosis of acute cholecystitis according to Tokyo Guidelines (TG18) criteria.
• Planned urgent/emergency laparoscopic cholecystectomy during the index admission, as determined by the treating surgical team.
• Ability to provide written informed consent prior to surgery.

Exclusion Criteria:

• Known hypersensitivity or contraindication to indocyanine green (ICG) or its excipients.
• Pregnancy or breastfeeding.
• Clinical situation preventing protocol implementation or informed consent (e.g., life-threatening emergency requiring immediate surgery without time for study procedures).
• Primary open cholecystectomy planned (i.e., not intended laparoscopic approach).
• Any condition that, in the investigator's opinion, makes participation unsafe or not feasible.

Individual participant data underlying the results reported in publications from this study (after de-identification), including the study protocol, statistical analysis plan, and analytic code, may be shared with qualified researchers upon reasonable request. Requests will be reviewed by the principal investigator and the study steering committee to ensure that the proposed use is scientifically valid and ethically appropriate. Data will be made available after publication of the primary results and will require a data sharing agreement.

Due to the nature of the surgical intervention, the operating surgeon cannot be blinded to treatment allocation. However, postoperative complications will be assessed by independent outcome adjudicators blinded to treatment assignment.