Tract dilation monitored by ultrasound in percutaneous nephrolithotomy: feasible and safe

To investigate the feasibility and safety of tract dilation monitored by ultrasound in percutaneous nephrolithotomy (PCNL) and identify suitable patients for this technique.

Patients who underwent PCNL with only one access (24 Fr) using the balloon dilator or sequential dilators (Amplatz and telescopic metal dilators) from December 2014 to May 2018 in Beijing Tsinghua Changgung Hospital were retrospectively reviewed. Patients' demographic information, intra- and postoperative data were analyzed. Factors which would increase the success rate of ultrasound-guided balloon dilation were investigated by logistic regression analysis.

There were 986 PCNLs performed. 207 cases underwent balloon dilation, while 411 underwent sequential dilation. The two groups did not significantly differ in age, sex, BMI, stone diameter, access location, operation time, postoperative complication rate, and stone-free rate. The balloon dilation group comprised 207 patients (115 males, 92 females) with a mean age of 51 ± 10 years. Mean BMI was 25.2 ± 3.3 kg/m². Mean stone size was 3.6 ± 1.2 cm, 47.3% of which were staghorn stones. Hydronephrosis of the targeted calyx occurred in 78.3% of patients. Within the balloon dilation group, tract dilation failed in 24 cases (11.6%) on the first attempt. The successful and failed subgroups had comparable outcomes. Multivariate analysis revealed that the risk factors for the failure of access establishment were the presence of staghorn stones (p = 0.032), prior ipsilateral open nephrolithotomy (p = 0.026), and lower pole access (p = 0.039), while the success rate was significantly higher in those with a hydronephrotic target calyx (p = 0.001).

Tract dilation using balloon catheter can be safely monitored by ultrasound, and is most suited to patients with a hydronephrotic target calyx.