Routine flexible nephroscopy for percutaneous nephrolithotomy for renal stones with low density : a prospective, randomized study

Purpose: We evaluated the usefulness of routine flexible nephroscopy during percutaneous nephrolithotomy. Materials and Methods: Patients diagnosed with kidney stones who were scheduled to undergo percutaneous nephrolithotomy between March 2011 and July 2012 were randomized into 2 groups. Group 1 underwent standard percutaneous nephrolithotomy using rigid nephroscopy. Group 2 underwent flexible nephroscopy, in addition to standard percutaneous nephrolithotomy and laser lithotripsy or basket catheter stone extraction, as needed. Surgery was performed subcostally and with minimal percutaneous access in group 2 to use the advantages of flexible nephroscopy. We compared the 2 groups in terms of preoperative stone characteristics and postoperative success criteria, including the stone-free rate, bleeding, number of access sites, etc. Results: The study included 61 males (76.3%) and 19 females (23.8%) with a mean +/- SD age of 43.75 +/- 12.4 years (range 19 to 74). There was no significant difference in stone size, HU density or stone location between the 2 groups. Comparison of perioperative and postoperative parameters revealed a higher stone-free rate (92.5% vs 70%), fewer access sites and a lower hematocrit decrease in group 2. The stone-free rate was higher in patients with stones with a density of less than 677.5 HU (100% in group 2 vs 64.7% in group 1). Conclusions: Routine flexible nephroscopy during percutaneous nephrolithotomy was associated with a higher stone-free rate, fewer interventions and less bleeding, especially in patients with low HU density stones.