A novel spherical-headed fascial dilator is feasible for second-stage ultrasound guided percutaneous nephrolithotomy: A pilot study

Objective

In second-stage percutaneous nephrolithotomy (PCNL), because the hydronephrosis has been decompressed, the dilated renal pelvis has resolved and the space is small. Consequently, introduction of the tip of the Amplatz dilator can cause injury to the opposite side of the renal-pelvic mucosa. In this study, we report the experimental and initial clinical performance of a spherical-headed fascial dilator developed specifically for second-stage PCNL.

Methods

The novel spherical-headed dilator was compared with existing tapered-headed dilators in configuration and in puncture resistance utilizing a static puncture test. Subsequently, a pilot clinical study was conducted during which patients scheduled to undergo second-stage PCNL from June 2019 to October 2019 in our center were enrolled. A typical ultrasound guided PCNL procedure was performed with the exception that the new spherical-headed fascial dilator was substituted for a tapered-headed one.

Results

Experimentally, stab resistance against polyethylene film was significantly increased using the novel spherical-headed dilator compared to the traditional tapered-headed dilators (p<0.005). In the clinical study, the novel dilators were successfully introduced into the renal pelvis and passed down the collecting system in all eight second-stage PCNL cases. There were no cases of renal pelvic perforation or brisk hemorrhage nor need for transfusion.

Conclusion

The design of the novel spherical-headed fascial dilator avoided the concentration of pressure at the tapered tip of the current Amplatz dilator by increasing the contact area and uniformly distributing and diffusing the pressure. Therefore, it is feasible to use the spherical-headed fascial dilator for second-stage PCNL.

conventional puncture dilation PCNL for kidney stones without hydronephrosis: a retrospective study

Background

Accurate puncture and dilation of the target kidney calices for percutaneous nephrolithotomy (PCNL) can be difficult. This study aimed to investigate the advantages of PCNL using optical puncture (i.e. the puncture is visualized on a screen as seen through the needle) combined with balloon dilation vs. conventional puncture methods.

Methods

This was a retrospective study of 58 consecutive patients with kidney stones without hydronephrosis and treated at the Minimally Invasive Urology Center of Zhejiang Provincial People’s Hospital between 10/2016 and 12/2017. Twenty-one patients underwent optical puncture combined with balloon dilation PCNL. Thirty-seven patients underwent conventional puncture instrument dilation PCNL (controls). Success rate, tubeless rate, blood loss, pain, and complications were compared between the two groups.

Results

The one-time puncture success rate (95.2% [20/21] vs. 67.6% [25/37], P = 0.02) and the postoperative tubeless rate (81.0% [17/21] vs. 54.1% [20/37], P = 0.04) were higher in the optical puncture group compared with controls. The average postoperative hemoglobin reduction was smaller (1.13 ± 0.63 vs. 1.56 ± 0.59 g/dL, P = 0.01), the postoperative VAS score was lower (1.6 ± 0.9 vs. 2.5 ± 1.2, P = 0.004), the rate of postoperative analgesic use was lower (14.3% [3/21] vs. 40.5% [15/37], P = 0.04), and the postoperative mean hospitalization days was shorter (3.7 ± 0.9 vs. 4.4 ± 0.8, P = 0.005) in the optical puncture group vs. controls. There was no case of urinary sepsis, blood transfusion, perirenal hematoma, pleural injury, and visceral organ damage.

Conclusions

Optical puncture combined with balloon dilation PCNL could be associated with good therapeutic effect and low frequency of complications for the treatment of kidney stones without hydronephrosis.