Diagnosis and treatment of renal and ureteral calculi.

Nephrolithiasis affects about 0.2% of the US population annually with about 5% to 15% of the population suffering at some point in their lives. While 75% of all calculi are calcium based, the remainder are composed of uric acid, cystine, struvite, or are composed of more than one substance. A 1997 policy update by the American Urological Association recommends that stones lodged in the ureter that are not causing excruciating pain for the patient are best initially managed by observation.