Intraoperative localization of renal calculi by ultrasound scanning

A total of 30 patients with multiple calyceal or pyelocaliceal calculi undergoing stone surgery were studied from January, 1991 to June 1992. An Ekoline real-time ultrasound machine operating at 5 MHz was used intraoperatively. Twenty-two out of 30 patients were identified to have residual stones. Complete clearance of all calculi as noted in 8/30. There were 2 false positives and 2 false negatives. The overall accuracy rate of the procedure was 86%, 90% sensitivity and 75% specificity rate. Certain limitations were identified contributing to the increased presence of retained stones. However, specific advantages were also noted, i.e. non-invasiveness, precise localization of non-palpable stones, and no irradiation exposure.(Author)