[The small urinary calculus: natural course and current treatment concepts].

Depending on size, duration of symptoms and their location in the collecting system urinary calculi may pass spontaneously in 16 to 93% of cases. The rate of infection and increase in size of stones in the renal pelvis or calix reaches 70% within months to years. Ureteral stones, however may lead to complications during a period of days to weeks. New minimally invasive treatment modalities have liberalized the indications for early intervention in cases of small stones.