The objective of the study is to improving the results of surgical treatment of liver echinococcosis complicated by biliary fistula by optimizing diagnostic approaches to early verification of this complication and improving the tactical and technical aspects of its elimination.

Inclusion Criteria:

• Age under 18 years;
• Informed consent for inclusion in the study;
• The presence of liver echinococcosis, for which conservative surgical treatment will be performed;
• The presence of the entire spectrum of necessary preoperative diagnostic measures;
• A full description of all stages of surgical intervention, indicating the type of intervention (open or laparoscopic surgery, location and size of the echinococcal cyst in the liver, type of antiparasitic treatment, presence or absence of a biliary fistula in the residual cavity, actions taken in relation to the fistula, the option of eliminating the residual cavity and drainage;
• Availability of objective data on the characteristics of the postoperative course, including dynamic indicators of the patient's condition, temperature, amount and nature of discharge through the drainage, the time of drainage removal, the type of complications (if any) and the method of their treatment, the duration of the hospital period, data on the characteristics of the posthospital period up to 3 months of observation;
• Absence of concomitant pathology that may affect the outcome of the surgery.

Exclusion Criteria:

• Age under 18 years;
• Refusal to participate in the study;
• Extrahepatic echinococcosis without liver damage;
• Absence of the full range of preoperative diagnostic data;
• Difficulties with objective analysis of the features of the performed surgical treatment;
• Incomplete data on monitoring the postoperative hospital and remote (up to 3 months) period;
• The presence of concomitant pathology that may affect the outcome of the operation.