Urinary Lithiasis

Annual incidence of stone disease is 16.4 per 10,000.

Lifetime prevalence is 1–15%, although this varies with age, gender, race, and geography.

Men are affected 2-3 times more often than women, but this varies with race.

Racially, prevalence highest among Caucasians, followed by Hispanics, Asians, and African Americans.

Peak incidence in fourth-sixth decades of life.

Increased risk of recurrence after first stone.

Morbidity and mortality very low if stone is not obstructing ureter; however, relative morbidity increases with obstructing ureteral stone in setting of UTI, especially if signs of systemic inflammatory response.

Urosepsis, possibly septic shock, if surgical procedure is performed in presence of UTI, especially with an obstructing ureteral stone.

Decreased renal function from partial or complete renal obstruction.

Perinephric hematoma if kidney is punctured by lithotripter during stone breakdown.

Pregnancy testing of women of childbearing age because of ESWL. Lithotripsy is contraindicated during pregnancy, although ureteroscopy and lithotripsy of stone under direct visualization is only relatively contraindicated and is often necessary if the stone obstructs drainage to the bladder, especially given excessive urine production during pregnancy.

An obstructing ureteral stone with signs of infection (tachycardia, hypotension, toxic appearance) is considered a urologic emergency, as the infected/obstructed urine constitutes an abscess.

Stones are classified as containing calcium: Calcium oxalate (60%), hydroxyapatite (20%), or brushite (2%); or noncalcium: Uric acid (7%), struvite (7%), cystine (1–3%), and other minor contributors.

Calculi <4 mm in diameter usually pass with conservative management (hydration, NSAIDs, tamsulosin)

Approximately 20% of stones cause severe enough symptoms to require surgical removal.