Introduction. The structure of the calyx-pelvic system may affect the results of treatment in patients with single and multiple renal calculi. The aim of the study was to evaluate the clinical significance of the anatomy of the renal cavity system during micropercutaneous nephrolithotripsy.

Material and methods. Sixty-one patients with kidney stones up to 2 cm participated in the study. All patients were subjected to micropercutaneous nephrolithotripsy (PNL) and divided into two groups. Group A included 34 patients with single renal concrements, group B was formed by 27 patients with multiple stones. The studied parameters were: efficiency, number of percutaneous accesses, operation time, number and structure of complications. All the studied parameters were correlated with variants of the anatomical structure of the renal pelvis system according to the classification of R. Takazawa. Type I was characterized by the presence of a single pelvis, type II is represented by a branched pelvis system.

Results and discussion. Operative treatment was successful in 46 (75.4%) patients. In group A, «stone-free state» was achieved in 15 (83,3%) patients with type I structure of the single pelvis and in 13 (81.3%) observations with branched pelvis (p>0.05). In group B stones were removed in 11 (73,3%) cases with type I structure of the cavity system and in 7 (58,3%) patients with branched pelvis (p<0,05). In patients with single stones, multiple accesses were performed only in 1 (2,9%) episode. In group B, multiple accesses were performed in 13 (48,1%) cases with a tendency to increase this indicator in type II of the pelvis structure. The average duration of operative treatment was 70,9±9 min. The operation time in the group with single stones at I and II types of the cavity architectonics was 62,5±5 min and 64,1±7 min respectively (p>0,05). In group B the duration of micro-PNL in case of solitary pelvis was significantly lower than in patients with branched type of pelvis system – 80,5±6 min vs. 96,3±11 min respectively (p<0,05). The total number of complications among all categories of patients amounted to 15 (24,6%) cases. In group A undesirable consequences were recorded in 3 (16,7%) observations in case of type I single pelvis and in 3 (18,8%) patients with branched pelvis (p>0,05). In group B, complications were established in 4 (26,7%) patients with type I pelvis and in 5 (41,7%) cases with branched variant of the cavity system (p<0,05).

Conclusion. The architecture of the renal pelvis system in patients with single stones up to 2 cm does not significantly affect the results of surgery and is important only in percutaneous access. The branched type of renal cavity structure (type II according to R. Takazawa classification) is accompanied by decreased efficiency and increased operation time, number of accesses and complications in patients with multiple renal stones.