The prevalence of silent kidney stones--an ultrasonographic screening study.

OBJECTIVE Silent and not yet discovered stones of the upper urinary tract are potentially dangerous, since in due course they may cause infection, obstruction and renal damage. The aim of this study was to determine the prevalence of such silent kidney stones in a representative Pakistani population of Karachi. SUBJECTS AND METHODS We studied 201 consecutive subjects at our hospital who underwent additional kidney screening whilst undergoing abdominal ultrasound. All these subjects did not have a history or symptoms of urolithiasis. RESULT We found silent kidney stones in 3% of subjects. All stone bearers were males. Most stones were in the left kidney. Notably, multiple stones and stones of a considerable size went unnoticed. CONCLUSION In addition to the usual figures of incidence and prevalence of stone disease drawn from patient data, there is a prevalence of 3% silent stones that may only be discovered incidentally or by screening. This is true for a "'stone country" like Pakistan. Figures for other regions have yet to be determined. Due to socioeconomic reasons, we believe that a general kidney screening for urolithiasis is, however, not indicated, at least in our country.