One shot renal dilation versus gradual metal telescopic dilation technique in percutaneous nephrolithotomy: comparison of safety and effectiveness

Clemente Meccariello1, Maurizio Fedelini1, Luigi Pucci1, Gaetano Battaglia1, Francesco Chiancone1, Domenico Di Lorenzo1, Paolo Fedelini1
  • 1 AORN A. Cardarelli, U.O.C. Urologia (Napoli)


Renal dilation (RD) is an important step in percutaneous nephrolithotomy (PCNL). It is usually done using metallic telescopic dilators (Alken), sequential fascial dilators (Amplatz), and single-step balloon dilator (BD). Despite its high costs, BD is considered the most modern and safest system. The aim of this study was to evaluate the feasibility of one-shot (OS) RD versus metallic telescopic (MT) dilation technique for tract creation in PCNL (1).

Materials and Methods

We enrolled 90 consecutive patients whose underwent PCNL for a renal stone at our institution from October 2015 to September 2016. The patients were randomized into two groups, with the first (Group A) having OS RD using the 30-F Amplatz dilator, and the second (Group B) having gradual dilation using the MT dilators (Alken). Intraoperative outcomes were collected in a prospectively maintained database and analyzed. Postoperative complications have been classified according to the Clavien-Dindo (CD) system (2). The stone-free rate was assessed using a plain abdominal film on the day after surgery. Statistical analyses were conducted using SAS version 9.3 software (SAS Institute, Inc., NC). Mean values with standard deviations (±SD) were computed and reported for all items. Statistical significance was achieved if p-value was ≤0.05 (two-sides).


All procedures were performed by a single surgical team in the prone position. There were no differences in the demographics and baseline characteristics between the two groups. In all patients of the Group A there was renal access with correct tract dilation except for 9 out of 45 (20%) patients in which a shift from the OS to the MT dilation was needed. There was a significant differences in successful dilation (p=0.0095). There were no significant differences in transfusion rate (p = 0.56) and in hemoglobin decrease (p = 0.60) between the two groups. OS dilation had significant shorter access time (p = 0.019) and X-ray exposure time (p=0,031) than MT dilation. There were no significant differences in stone-free rates (p=0.56) and in complication rates (p=0,65) between the groups. Table 1 reports post-operative complications according to CD systems.


Tract dilatation is an important step in PCNL, and inadequate RD can lead to a failure of the procedure or to provoke bleeding. In our department RD is classically done using metallic telescopic dilators (Alken) or single-step balloon dilator. The single-step balloon dilator is a safe but expensive technique. Even if in 9 patients of the Group A a shift from the OS to the MT dilation was needed, no significant differences in transfusion and complication rates were seen. Moreover OS dilation had significant shorter access time. In our opinion the difficulty encountered to obtain an adequate access using the OS dilation, could be related to the difficulty to perforate the layers of abdominal wall and the Gerota’s fascia.


OS RD is a cheap, effective and safe technique for tract creation in PCNL, with shorter access time and X-ray exposure time and without increased complications.


1- Nour HH, Kamal AM, Zayed AS, Refaat H, Badawy MH, El-Leithy TR.Single-step renal dilatation in percutaneous nephrolithotomy: A prospective randomised study. Arab J Urol. 2014 Sep;12(3):219-22.

2- de la Rosette JJ, Opondo D, Daels FP, Giusti G, Serrano A, Kandasami SV, Wolf JS Jr, Grabe M, Gravas S.Categorisation of complications and validation of the Clavien score for percutaneous nephrolithotomy. Eur Urol. 2012 Aug;62(2):246-55.