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

Abstract

ObjectiveTo present our novel miniaturised endoscopic system and describe a step-by-step guide for successful implementation of the super-mini percutaneous nephrolithotomy (SMP). Patients and MethodsThe new-generation SMP endoscopic system consists of (i) a 40 000-pixel super-mini nephroscope with an 8.0-F outer diameter and 7.5-F inner diameter dismountable sheath, and (ii) a newly designed irrigation-suction sheath available in either 12 F or 14 F. The irrigation-suction sheath is a twolayered metal structure. The key feature of the irrigationsuction sheath is to allow irrigation and suction respectively (the inflow through the space between the two layers of the sheath, the outflow through the central lumen of the sheath). This property improves irrigation and stone clearance despite reduced instrument dimension. In all, 59 patients with renal stones underwent new-generation SMP between April 2016 and December 2016. The percutaneous tract dilatation was carried out to 14 F. Lithotripsy was performed using either holmium laser or a pneumatic lithotripter. Stone fragments were sucked out by vacuum suctioning through the sheath. A nephrostomy tube or JJ stent was placed only if clinically indicated. Low-dose computed tomography was performed to assess the stone-free status on the morning after the procedure. ResultsThe mean stone burden was 2.4 cm. Of the 59 patients, nine had diabetes and five had hypertension. SMP was completed successfully in all patients with a mean operation duration of 32.9 min and a mean haemoglobin decrease of 13 g/L. The stonefree rate was 91.5%. Complications occurred in 5.1% of the patients, all of them were Clavien-Dindo Grade I (minor fever managed by antipyretic therapy), and no transfusions were needed. ConclusionThe new-generation SMP system is safe, feasible, and effective for managing renal calculi of <3 cm, with the advantages of a small percutaneous tract, less blood loss, high efficacy in stone clearance, improved visual field, short operation duration, and ease of operating.

Treatment of Complex Renal Calculi by Digital Flexible Ureterorenoscopy Combined with Single-Tract Super-Mini Percutaneous Nephrolithotomy in Prone Position: A Retrospective Cohort Study

“…These developments include miniaturized PCNL equipment and flexible ureteroscopes. The new super-mini-PCNL (SMP) system requires a small percutaneous tract for access, so there is less blood loss and there is also effective stone clearance, the visual field is good, and the operation duration is short, with easy operation [12,13]. Flexible ureterorenoscopy (URS) does not require a new tract for access because it can use natural ones such as the urethra, ureter, or renal pelvis.…”

“…Most urologists tend to use either digital flexible URS or single-tract miniaturized PCNL to treat renal stones, with great success [15,16]. However, these techniques cannot resolve all cases with multiple kidney stones, resulting in a low stone-free rate and complications in some patients [12,14]. Previous reports have demonstrated that miniaturized PCNL combined with digital flexible URS is safe for pediatric [17] and adult patients [18] with multiple kidney stones and for adults with large stones [19,20].…”

Miniaturised percutaneous nephrolithotomy: Its role in the treatment of urolithiasis and our experience

“…This design restricted irrigation flow once a laser fibre or pneumatic lithotripter device was inserted, leading to suboptimal visualization requiring longer operative times. To overcome this limitation, the new-generation SMP utilizes a novel irrigation-suction sheath to improve irrigation, which also enables the use of more efficient stone fragmentation devices to improve stone clearance [39] .…”

“…The SMP telescope has a 1.4 mm working diameter with a 40 000-pixel resolution. The sheath consists of a two-layered metal structure, available in either 12 or 14 Fr [39] . The space between the two layers of the sheath forms an independent irrigation channel, and the central lumen of the sheath works as a conduit for continuous suction.…”

Is supermini‐percutaneous nephrolithotomy a new way forward?

“…To overcome these deficiencies of mini‐PCNL, Prof. Guohua Zeng developed super‐mini‐PCNL (SMP) . The basic components of the SMP system are a miniaturized nephroscope with an irrigation‐suction sheath.…”