An osmotic diuresis phenomenon appearing in renal colic during urography was refered. The pressures occurent in renal pelvis during obstruction of ureter and normal conditions were described. The pressure surge patomechanism in renal collecting system as a cause of renal rupture and retroperitoneal extravasation of urine was discussed. Another causes of extravasation of urine were mentioned. Case description. The patient case with ureterolithiasis (stone placed in ureteric orifice) complicated with spontaneous pelvic rupture. The extravasation of urine and ureterolithiasis were confirmed by ultrasonography and urography. Temporary nephrostomy and antibiotic therapy were performed. The stone underwent spontaneous passage. Absence of characteristic symptoms of urine extravasation makes the diagnosis difficult, requiring additional imaging studys. Proper differentiation of real urine extravasation from diffusion through the renal parenchyma to the perirenal area due to osmotic diuresis is important part of diagnosis. Elevated inflammatory parameters and infection of urinary tract often coexist with peripelvic extravasation. Ureterolithiasis complicated by urinary tract infection requires renal drainage and antibiotic therapy as a first-line treatment. Either nephrostomy or antibiotic therapy are successful treatment of urine extravasation.