Introduction. The article presents the results of micropercutaneous nephrolithotripsy (Micro-PNLT) application in the large stonestreatment. This method was first described by M.R. Desai in 2011, and since then the MicroPNLT potential in the urolithiasis treatment is actively discussed in the medical literature. The Micro-PNLT kit was registered for use on the territory of the Russian Federation in 2018.

Materials and methods. 43 patients with urolithiasis and a 20 mm or more stone (average stone size 21.4±1.3) underwent MicroPNLT in the SBI of public health “St. Luke's Clinical Hospital”.

Results. The average stone size was 21.4±1.3 mm (20-25 mm), the average stone density - 1191±1184 HU, the average operation time - 89.5± 12 min, the preoperative hemoglobin level - 138±10.5, hemoglobin after surgery - 136±10.9.

JJ stent with traction of the stent thread through the skin of the lumbar was placed intraoperatively in 30 patients; three patients received 8 Ch nephrostomy, which was removed on the second day after the operation; 10 patients completed the operationwithoutinstalling any drains.The average time of hospitalizationwas 3.4±1.3 days, complete cessation of calculus (SFR) was observed in 85.9% of patients. Renal colic in patients who did not have a JJ-stent or nephrostomy (10 patients) was the only noted complication. No significant complications were noted.

Discussion. Nowadays urologists have microsurgical instrumentsfor access to the kidney, which reduce the number of complications. Therefore, medical conditionsfor endourological operations(PNLT,retrograde nephrolithotripsy) are expanding. However,standard PNLT remainsthe “gold standard” fortreating large kidney stones. In order to reduce renal parenchyma trauma, micropercutaneous nephrolithotripsy is increasingly used. Studies comparing the results of micro and standard PNLT showthat Micro-PNLT issuperiorto standard PNLT in terms of the bleeding frequency and the length of hospitalization. It is also noted that the size of the duct created during kidney access affects the frequency of hemorrhagic complications. In our study we showed that the use of the ureteral coverreduced the number ofresidual fragments and opened up prospects for the treatment of stones larger than 20 mm.

Conclusions. MicroPТLTis a relatively new method in the treatment of kidney stones; the firstresults allowusing it in patientswith large and single kidney stones, in patients who previously underwent open operations; in patients with complex anatomy ofthe cup-pelvis-plating system,for example,with long (more than 2 cm) and narrow necks of cups. Using Micro-PNLT in this situation significantly reduces the risk of bleeding, while using standard PNLT in case of a narrow neck increases it. It is necessary to study further the results of MicroPNLT with large kidney stones, as well as in patients taking anticoagulants.

Authors declare lack of the possible conflicts of interests