The "Mini-Perc" Technique of Percutaneous Nephrolithotomy with a 14-Fr Peel-away Sheath: 3-year Results in 72 Patients

OBJECTIVE: To assess the efficacy and safety of a "mini-perc" technique of percutaneous nephrolithotomy using a 14-Fr peel-away sheath for the removal of pyelocaliceal stones, and to determine appropriate inclusion criteria. MATERIALS AND METHODS: From July 1999 to June 2002, the medical records and radiographic images of 72 patients who underwent the "mini-perc" technique of percutaneous nephrolithotomy with a 14-Fr peel-away sheath, were reviewed to determine clinical history, stone characteristics, immediate stone free rate, final stone free rate after additional procedures, complications, and hospital stay. We also analyzed the effect of the longest stone diameter, the cumulative longest diameter of stones, the cumulative stone burden, and the stone density on the immediate stone free rate using a Fisher exact test. RESULTS: The only major complication, arterial bleeding, occurred in a patient with Child A liver cirrhosis and was successfully treated by embolization with coils and a gelatin sponge. The immediate stone free rate was 80.6 %, which was significantly influenced by stone diameter but not stone density. The mean hospital stay after the procedure was 3.97 days. CONCLUSION: The "mini-perc" technique of percutaneous nephrolithotomy, which uses the 14-Fr peel-away sheath, is a safe and effective modality for treating renal calculi.

Comparison of CT Urography and Intravenous Urography in Patients with Hematuria

PURPOSE: We wanted to compare CT urography (CTU) with using multi-detector row CT (MDCT) and intravenous urography (IVU) for diagnosing the causes of hematuria. MATERIALS AND METHODS: From January 2003 to March 2004, IVU and CTU were obtained in 48 patients. We evaluated the causes of hematuria in 34 of 48 patients. The IVU images were obtained by the conventional method. The CTU images were routinely obtained before intravenous contrast injection, and at 2 and 5 minutes after intravenous contrast injection. In case of delayed excretion of contrast by the kidneys, the delayed CT scans were obtained at 120 minutes after contrast injection. All the CT images, including the axial and 3D coronal reformatted CTUs with using software as well as conventional IVU images, were reviewed by two radiologists working in consensus. We decided if urinary stone existed or not and we looked for the indirect signs such as hydronephrosis or delayed excretion, etc. We also observed if it was possible to determine the mass, ureteral stricture and enhancement of the ureteral wall, etc. We calculated sensitivity, specificity, positive predictive value and negative predictive value for each modality to diagnose urinary stone. We compared the detection rate according to the phases of CTU. RESULTS: We confirmed the presence of urinary tract stones in 27 of 34 patients who had undergone both IVU and CTU. We diagnosed ureteritis in 1, transitional cell carcinoma in 5 and acute pyelonephritis in 1 of the remaining 7 patients. The urinary stones were detected in fifteen patients on both IVU and CTU (15/27, 55.6%). We detected the urinary stones on CTU, but not IVU, in twelve patients (12/27, 44.5%). The sensitivity to detect the urinary stones was 100% (27/27) on CTU and 55.6% (12/27) on IVU respectively. The specificity was 100% (7/7) on IVU and CTU, respectively. The positive predictive value was 100% (15/15) on IVU and 100% (27/27) on CTU, respectively. The negative predictive value was 36.8% (7/19) on IVU and 100% (7/7) on CTU. Precontrast CTU demonstrated the urinary stones in all 27 patients (100%, 27/27). On the other hands, urinary stones were detected in 19 patients (19/27, 70.4%) and 8 patients (8/27, 29.6%) at 2 and 5 minutes on CTU, respectively. CONCLUSION: CTU is superior to IVU to diagnose the causes of hematuria such as urinary tract stone or extrarenal lesion. Precontrast CTU is the most useful modality for the detection of the urinary tract stone of the other enhanced CTUs.