Place of non contrast thin-slice spiral computed tomography in evaluation of stone-free ratio after percutaneous nephrolithotomy.

PURPOSE To search the place of non contrast abdominal computed tomography to detect the stone-free rate after percutaneous nephrolithotomy (PNL) and the clinical importance of its superiority against to plain film radiography (KUB). MATERIALS AND METHODS Between February 2006 and July 2010, 62 patients including 27 women had no stone detected peroperative fluoroscopy and nephroscopy during PNL were included. Patients whom stone was not detected under 5 mm section upper abdomen non contrast spiral CT and KUB control in postoperative day 3 were defined as Group 1; patients whom stone was detected in a single slice CT were defined as clinically insignificant fragment (CIF)(Group 2) and patients whom stone was detected at least in two slice were defined as rest fragment (Group 3). RESULTS Median stone size were 22.3 mm (19-37 mm). Preoperative stone localization of groups were upper calyx, middle calyx, pelvis, lower calyx and 2.1, 14.9, 25.5 and 57.4%, respectively. CIF was detected in postoperative CT control of 12 (25.5%) patients whom stone was not followed in KUB and rest fragment was detected in 6 (12.8%) patients. Three of patients whom rest fragment was detected required an additional intervention for stone. CONCLUSION KUB which is routinely used to determine stone-free ratio after PNL operation is not sufficient to detect rest calculi and/or CIF existence in 38.3% patients. But when it is considered that most of rest stones detected were CIF and only 6.3% patients had additional intervention required rest calculi. We can think that CT follow-up is not absolutely required.