An Innovative Free-Hand Puncture Technique to Reduce Radiation in Percutaneous Nephrolithotomy Using Ultrasound with Navigation System Under Magnetic Field: A Single-Center Experience in Hong Kong.

OBJECTIVE

Traditionally, fluoroscopy or ultrasound (US) or both are used for guiding tract creation during percutaneous nephrolithotomy (PCNL). However, the use of fluoroscopy inevitably incurs radiation exposure, which should be cut down as much as possible in view of its potential adverse effects on health: both deterministic effects and stochastic effects. Conventional US guidance, being radiation free, can serve the purpose, but it is difficult to visualize the needle tract during screening without a needle-guiding system fixed to the transducer, and hence, there is a lack of predictability and sense of security. The objective of this study is to assess the feasibility of using US with navigation system (USNS) to solve the above problems.

PATIENTS AND METHODS

In 2014, we performed PCNL on 18 patients with USNS guidance. During the puncture step, the magnetic field-based navigation US could help visualize the position of the needle tract in relation to the target calix. The procedure was done in free hand without the usage of needle-guiding system attached to the transducer. Needle deviation could be detected and adjusted immediately to achieve precise puncture.

RESULTS

Of the 18 patients, 83.3% (15/18) of them had their punctures effectively done with a single attempt. Three puncture procedures were performed by two urologic trainees without any previous USNS experience. The mean fluoroscopy time during dilatation was 74.6s, with no radiation at all during the puncture step. The stone clearance rate was 72.2%, with 66.7% (12/18) being tubeless procedures. The mean length of hospital stay was 4.8 days. No immediate complications related to the puncture procedure were found.

CONCLUSIONS

USNS can provide radiation-free guidance for tract creation in PCNL. It is predictable, precise, reliable, and safe. Most importantly, the technique is easy to learn, particularly for urologists who are new to PCNL.