The aim of the study was to compare the ultrastructural changes in the renal parenchyma with the results of postprocessing CT analysis with contrast enhancement in patients with urolithiasis.

Inclusion Criteria for experimental group:

1. Men and women >18 years and <45 years old;
2. Established diagnosis of urolithiasis that does not interfere with the processes of urodynamics (there is no expansion of the overlying urinary tract);
3. Planned surgery - percutaneous nephrolithotripsy;
4. Stone size up to 20 mm., Patients with multiple small two-sided stones;
5. Patients with CT of the kidneys with contrast enhancement performed according to the required protocol.

Exclusion Criteria for experimental group:

1. Age < 18 years old or ASA> 3;
2. With single kidney;
3. Patients with coral stones;
4. The presence of concomitant systemic pathology (DM, AH), as well as kidney disease (glomerulonephritis), which can change the state of the renal parenchyma;
5. A history of injuries and surgical interventions on the kidneys, urinary tract, renal vessels;
6. Taking nephrotropic drugs;
7. Systemic intake of nephrotoxic drugs;
8. Severe general somatic condition, making the operation impossible;
9. Pregnancy.

Inclusion Criteria for control group:

1. Men and women >18 years and <45 years old;
2. Absence of urolithiasis in the patient's anamnesis and in his family history;
3. Renal tumors which have undergone partial nephrectomy or nephrectomy;
4. Patients with CT renal data with contrast enhancement, performed according to the required protocol.

Exclusion Criteria for control group:

1. Urolithiasis in anamnesis;
2. A history of trauma and surgical interventions on the kidneys, urinary tract, renal vessels;
3. Intercurrent background;
4. Non-informative biopsy.