The results of retrospective analysis of treatment outcome of 169 patients with acute surgical pathology of abdominal organs complicated by various forms of peritonitis, 79 of whom developed postoperative complications, are presented. The dependence of occurrence and severity of complications on the nature of the underlying disease, clinical manifestations of peritonitis before surgery, anthropometric data research, laboratory methods, Mannheim peritonitis index parameters, comorbidity class, age were studied, using the analysis of variance. As a result, a scale according to which the prediction of complications is conducted in two stages, was developed. Before the surgery, we estimate the previous risk according to the nature of the underlying disease, clinical manifestations of peritonitis, comorbidity class. According to identified changes, the final estimation due to the nature of the underlying disease, Mannheim peritonitis index parameters, comorbidity class, stab neutrophil leukocytes number, use of programmed peritoneal cavity sanations is being made during the operation. These indicators provided a certain number of points. Due to these points, patients were referred to several groups: normal group (less than 18), increased (18-25), medium (26-34) and high (more than 35) the risk of complications. This distinction makes it possible to apply the necessary preventive measures at all stages of treatment, since preoperative preparation.

The ability to predict the possibility of postoperative complications is an important component of treatment of acute peritonitis. None of the known methods is fully accepted worldwide.The objective of the research was to develop an informative method for predicting postoperative complications.Materials and methods. A retrospective analysis of the results of treating 169 patients with peritonitis was made. 79 patients developed postoperative complications. 39 patients died.  123 patients were diagnosed with comorbidities. Clinical and laboratory data, parameters of the Mannheim peritonitis index, comorbidity class, and the patients’ age were analyzed using the variance analysis.Results and discussion. The prediction of postoperative complications may be carried out in two stages. Prior to surgery, preceding risk is estimated considering the nature of the underlying disease, clinical signs of acute peritonitis and comorbidity class. During surgery the final risk estimation is made taking into consideration the nature of the underlying disease, the Mannheim peritonitis index, comorbidity class, the number of band forms, use of the programmed peritoneal sanation. For each aforementioned indicator different number of points was determined. Patients were divided into several groups by the sum of these points: normal (2-4 points), increased (5.7 points), medium (8-9 points) and high (more than 10 points) risk of postoperative complications.Conclusions.The proposed prognostic scale allows us to identify groups of normal, increased, medium and high risk of postoperative complications in acute peritonitis.A two-phase prediction - before and during surgery – allow us to differentially apply preventive measures in the preoperative preparation, during surgery and in the postoperative period of treatment.