Super‐mini percutaneous nephrolithotomy (SMP): a new concept in technique and instrumentation

Abstract

Objective To present a novel miniature endoscopic system designed to improve the safety and efficacy of percutaneous nephrolithotomy, named the ‘super‐mini percutaneous nephrolithotomy’ (SMP). Patients and Methods The endoscopic system consists of a 7‐F nephroscope with enhanced irrigation and a modified 10–14 F access sheath with a suction‐evacuation function. This system was tested in patients with renal stones of <2.5 cm, in a multicentre prospective non‐randomised clinical trial. In all, 146 patients were accrued in 14 centres. Nephrostomy tract dilatation was carried out to 10–14 F. The lithotripsy was performed using either a Holmium laser or pneumatic lithotripter. A nephrostomy tube or JJ stent was placed only if clinically indicated. Results SMP was completed successfully in 141 of 146 patients. Five patients required conversion to larger nephrostomy tracts. The mean (sd) stone size was 2.2 (0.6) cm and the mean operative duration was 45.6 min. The initial stone‐free rate (SFR) was 90.1%. The SFR at the 3‐month follow‐up was 95.8%. Three patients required auxiliary procedures for residual stones. Complications occurred in 12.8% of the patients, all of which were Clavien grade ≤II and no transfusions were needed. In all, 72.3% of the patients did not require any kind of catheter, while 19.8% had JJ stents and 5.7% had nephrostomy tubes placed. The mean hospital stay was 2.1 days. Conclusions SMP is a safe and effective treatment for renal stones of <2.5 cm. SMP may be particularly suitable for patients with lower pole stones and stones that ae not amenable to retrograde intrarenal surgery.

New technology in ureteroscopy and percutaneous nephrolithotomy

“…UMP may not require percutaneous nephrostomy (i.e., tubeless). The concept of super-minipercutaneous nephrolithotomy using 7 F nephroscope and a modified 10-14 F access sheath with suctionevacuation function is similar to UMP [27]. …”

“…Active washout could be used in several ways: by transportation of fragments within continuous irrigation backflow through access sheath alongside the scope; by filling of collecting system with high pressure and quickly remove the scope resulting in immediate inversion of irrigation flow and pressure with spillage-like removal of stones via the access sheath [27]; by sweeping fragments down the ureter; or by irrigation with a syringe via an additional channel of access sheath [26].…”

The new generation super‐mini percutaneous nephrolithotomy (SMP) system: a step‐by‐step guide

“…The key feature of the irrigation‐suction sheath is that it allows inflow and outflow respectively (the inflow is through the space between the two layers of the sheath, the outflow is through the central lumen of the sheath). This is completely different to the first‐generation SMP or traditional mini‐PCNL systems, wherein the inflow and outflow take place in the same lumen of the sheath. In the first‐generation SMP or traditional mini‐PCNL systems, the inflow can partially offset the effect of outflow and push the stone fragments back in to the collecting system, which can lead to migration of the stone and lengthening of the operation time.…”

Flexible ureteroscopic holmium laser lithotripsy with PolyScope for senile patients with renal calculi

“…The large gap brings many advantages, such as sufficient drainage which can reduce intrapelvic pressure effectively, great vortex effects which can accelerate stone extraction and decreased fraction between the lens barrel and the stone which can reduce the damage of lens barrel. iii) We recommend upgrading the PolyScope by adding a ‘handle’ just like the one used in SMP (27), consisting of a straight and an oblique bifurcated tube. The straight tube can be contiguous with the access sheath and has a receptacle for a silicone or rubber cap at the proximal end.…”