Indian Journal of Urology
: 2015  |  Volume : 31  |  Issue : 1  |  Page : 81--82

Percutaneous nephrolithotomy with routine flexible nephroscopy for low-density renal stones

Kuldeep Sharma 

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Sharma K. Percutaneous nephrolithotomy with routine flexible nephroscopy for low-density renal stones.Indian J Urol 2015;31:81-82

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Sharma K. Percutaneous nephrolithotomy with routine flexible nephroscopy for low-density renal stones. Indian J Urol [serial online] 2015 [cited 2020 Jul 2 ];31:81-82
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Percutaneous nephrolithotomy (PCNL) is considered the gold standard treatment for large complex renal calculi. However, it is difficult to visualize the entire intrarenal collecting system using a rigid nephroscope, [1] resulting in a disadvantage of an increased number of access points. A flexible nephroscope facilitates access to portions of the collecting system that might not be accessible using a rigid instrument. [2] This decreases morbidity due to the shearing force of rigid nephroscopy as well as the decreased number of access points, with increasing success rate in terms of stone clearances. In this study, patients undergoing PCNL for stones greater than 2 cm, between March 2011 and July 2012 (n = 80), were prospectively randomized into two groups. [3] Standard PCNL (n = 40) using a rigid nephroscope was included in group 1, whereas in addition to standard PCNL, flexible nephroscopy, laser lithotripsy or basket stone extraction were used in group 2 (n = 40). After 3 months post-operatively, patients were evaluated by plain X-ray of the kidneys, ureters and bladder and ultrasound or unenhanced computerized tomography. The study included 61 males (76.3%) and 19 females (23.8%), with a mean + SD age of 43.75 + 12.4 years (range 19-74). The groups were homogenous in mean age and similar in mean stone size, location and HU density. The primary measure of surgical success was stone-free rate, which was significantly higher in group 2 than in group 1 (92.5% vs. 70%, P = 0.022). The stone-free rate was significantly higher in patients with a stone density of less than 677.5 HU (100% vs. 64.7%, P = 0.018).


It is difficult to visualize residual stone fragments, especially of low density, by conventional fluoroscopy as well as by intraoperative ultrasound. [4] Thus, it is possible to improve PCNL efficacy by flexible nephroscopy. [5] In the current series, flexible nephroscopy was performed concomitantly with conventional PCNL to decrease the need for second-look nephroscopy, which is costly and undesirable for the patient and the surgeon.

The number of access sites and supracostal access were found to be lower in the flexible nephroscopy-added group, with the primary advantage of better stone-free status and fewer complications in terms of blood loss and hemothorax. The mean number of access sites was 1.4 in group 1 with conventional PCNL and 1.1 in group 2 with flexible nephroscopy (P = 0.019). The operative time in group 2 was slightly longer (88.8 ± 28.3 min (45-160) vs. 95.4 ± 29.3 min (55-185), P = 0.263). The post-operative hematocrit decrease was 6.2% in group 1 and 3.2% in group 2. Using a flexible nephroscope requires some expertise. Due to difficult orientation, fluoroscopic and operative times can be prolonged. Performing 16Fr flexible nephroscopy through the 28Fr access sheath used with a rigid nephroscope can cause irrigation fluid leakage around the sheath.

Although using a flexible nephroscope, LASER and stone retrieval basket add to the cost of the procedure, considering the morbidity of residual calculi and need of second procedure or extracorporeal lithotripsy, the option seems reasonable. Routine flexible nephroscopy is a logical, effective method that provides even more efficacy in patients with low HU density stones. Flexible nephroscopy decreased the number of access points and blood loss volume and increased the stone-free rate, especially in patients with low HU density stones. Because residual stones cannot be properly identified during conventional PCNL, a precise determination of surgical success is not possible. [5] Problems associated with residual stone imaging and the difficulty of reaching some inaccessible stones with a rigid nephroscope decreased the surgical success rate and increased the morbidity rate. Improved instrument design, such as flexible nephroscopes, nitinol graspers and forceps, and the introduction of the holmium: YAG laser, ultrasound and pneumatic devices have led to an increase in the PCNL stone-free rate.


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