Ureteroscopy is the most common interventional procedure before symptomatic ureteral, not amenable to shock wave, lithotripsy. It has a very high stone free rate. However, retrograde displacement of a calculus can occur during irrigation to maintain patency and vision, or due to the application of kinetic energy used for stone fragmentation. The reported migration rate varies from 2% to 60%.
Various modifications of the existing technique have been described including the use of ureteral baskets, Lithocatch ™, Lithovac™, Passport™ Balloon and the Dretler stone cone (Boston Scientific, Natick, Massachusetts) etc. All of these add to the cost and complexity of he procedure. We have described a simple maneuver during ureterscopy to prevent inadvertent retrograde stone migration.
We tested instillation of lidocaine gel, proximal to stone, before stone fragmentation in a randomized clinical trial. Our results indicate in two comparable groups with regard to age and stone size, stone or stone fragment migration occurred in 4% and 28% of patients in groups 1 (study) and 2 (control), respectively, and this difference was statistically significant (p = 0.002).
At 2 weeks follow-up with imaging, the stone-free rate was 96% and 72% in groups 1 and 2, respectively, and this difference was also statistically significant (p = 0.045). We concluded that Lidocaine jelly instillation, proximal to ureteral calculi during lithotripsy, is an effective method of preventing retrograde stone displacement as well as significantly improving the stone-free rate.
One of the limitations of this technique is that if the working channel of the ureteroscope is used for this purpose, it requires some force to push the jelly through. Additionally, instillation of jelly has the potential to impair visibility during ureteroscopy. We did not collect data specifically addressing this issue, however none of the participating urologists experienced this problem in the current study.