Outcomes following 'mini' percutaneous nephrolithotomy for renal calculi in children. A single-centre study.

INTRODUCTION: This retrospective review was undertaken to identify the postoperative outcomes of children undergoing 'mini' percutaneous nephrolithotomy (MPCNL) at a single institution. OBJECTIVE: Outcomes measured included: percentage of stone clearance, postoperative analgesia requirements, the need for intraoperative or postoperative blood transfusion, length of stay and morbidity. STUDY DESIGN: A total of 46 patients were reviewed over a two-and-a-half-year period; the mean age was 7.3 years (range: 1-16 years). The MPCNL was performed with a radiological-guided peripheral puncture, followed by dilatation of the nephrostomy tract to a maximum Amplatz sheath size of 16-French; an 11-French nephroscope was used. Stone disintegration was achieved either with pneumatic or laser lithotripsy. RESULTS: Complete stone clearance was achieved in 35/46 children (76%). The remaining 11 children had a stone clearance rate of over 80%. No patients required intraoperative/postoperative blood transfusion. A total of 39% of patients were managed on simple/non-opiate based analgesia, with 54% requiring opioid analgesia postoperatively for less than 24 h. There were no procedure-related complications and no mortalities. The mean length of stay was 2.24 days. DISCUSSION: The management of urolithiasis can be challenging in children. The use of percutaneous nephrolithotomy, is becoming increasingly popular in the treatment of paediatric urolithiasis. The stone clearance rate in children undergoing standard PCNL, has been reported to be 50-98% in the literature [1,2,3,4]. Samad et al. [2] in 2006, reported their experience in 188 consecutive PCNLs, using a 17Fr or 26Fr nephroscope. Their largest sub group included children aged >5-16 yrs. Within this group, 57% were treated with a 17Fr nephroscope and 43% with the 26Fr nephroscope, achieving stone clearance of only 47% with PCNL monotherapy. In this group the transfusion rate was 3% [2]. Badawy et al., reported their experience of 60 children in 1999, using a 26 or 28Fr Amplatz sheath. They reported an 83.3% stone clearance with single session PCNL, with only one procedure being abandoned due to intraoperative bleeding requiring blood transfusion [3]. In 2007, Bilen et al. reported their experience and compared the use of 26Fr, 20Fr and 14Fr (mini) PCNL. Stone size, previous surgery and the mean haemoglobin drop postoperatively did not change between the groups, however the blood transfusion rate was higher in the 26Fr and 20Fr Amplatz sheath groups. The stone clearance was highest in the 'mini PCNL' group at 90%, compared to 69.5% in the 26Fr and 80% in the 20Fr group [4]. MPCNL has become increasingly popular over recent years, with stone clearance reported as 80-85% [5-7] following a single session of MPCNL as monotherapy. In 2012, Yan et al. reported 85.2% stone clearance with mini PCNL monotherapy (tract size 14-16Fr), with no children requiring blood transfusion [6]. Zeng et al. reported their experience of 331 renal units in children, with stone clearance rates reaching 80.4% and a blood transfusion rate of 3.1% [8]. In our centre, we do not perform postoperative haemoglobin levels as a matter of routine and any investigations are performed on an intention to treat principle. Bilen et al. reported no blood transfusions being required in their cohort of patients undergoing MPCNL [4] and this is supported by Yan et al. [6]. CONCLUSION: Mini PCNL is an effective and safe procedure for the treatment of paediatric renal stones. In the present series, all children achieved greater than 80% stone clearance, none received a blood transfusion (intra/postoperatively) and there were no mortalities. Postoperative pain was managed with simple analgesia in 39%; however, the majority required opiate analgesia for less than 24 hours.