Introduction. Currently, percutaneous renal surgery is a common surgical procedure in urologic practice for the treatment of large and staghorn renal stones. Placement of a nephrostomy tube has been well recognized as a standard procedure to provide hemostasis, adequate drainage, and access for additional endoscopic procedures. At the same time, the use of a nephrostomy tube has negative consequences such as discomfort/pain symptom, longer hospital stay and possible urine extravasation. In view of the above, draining of the access tract raises questions in some cases.

The aim of the study was effectiveness of tubeless percutaneous nephrolithotripsy in the treatment of urolithiasis in children.

Materials and methods. Between 2013 and 2019, 66 patients (aged 1-17 y/o) underwent tubeless percutaneous nephrolithotomy (PNL) at the Department of Pediatric Urology of N. Lopatkin Scientific Research Institute of Urology and Interventional Radiology. Patients were divided into three groups depending on the size of the instruments and the way the operation was completed. The first group (n=28) underwent surgery using the mini-PNL technique with the closure of the access tract. The second group (n=21) underwent surgery using the mini-PNL technique in the end of the surgery, moderate bleeding along the tract was detected in order to stop bleeding, a hemostatic matrix with thrombin was introduced. The third group (n=17) underwent surgery using the standard PNL technique and moderate bleeding was also determined in this group with the aim of tubeless completion, a hemostatic matrix with thrombin was introduced. Drainage of the upper urinary tract in the postoperative period was carried out by "JJ"-internal and "J"-external ureteral stents, which were held for up to 14 days.

Results. The complete removal of the calculus in one surgical session was similar in all three groups. In the first group there were 26 (92.8%) children, in the second group 19 (90.4%) and in the third group 16 patients (94.1%). In the first group it was 26 (92.8%) children, in the second group 19 (90.4%) and in the third group 16 patients (94.1%). The need for additional interventions after surgical treatment was 21.4% in the first group, 23.7% in the second and 17.5% in the third group. Febrile fever (persistent temperature 380 C) most often occurred in the first group – in 10.7% of cases, while in the second and third groups this complication was detected in 4.7% and 5.8% of cases, respectively. Gross hematuria in the postoperative period was noted in the group without the use of a hemostatic matrix, averaging 35 (2-115) hours.

Conclusion. The proposed tubeless PNL with the use of a hemostatic matrix is indicated for children without bacteriuria, with complete removal of the calculus, in the absence of trauma of the pelvicalyceal system and intensive bleeding. The duration of gross hematuria decreased with the introduction of the matrix in standard tubeless PNL by 51.4% and in mini-PNL by 25.8% compared with the 1-st group