Ultrasonic-With-Ballistic Versus Pneumatic Lithotripsy in Percutaneous Nephrolithotomy for 2-4 cm Renal Calculi: A Prospective Quasi-experimental Comparative Study in a Bangladeshi Tertiary-Care Hospital.

Background Percutaneous nephrolithotomy (PCNL) is the standard treatment for large renal calculi, and the use of an intracorporeal lithotripter strongly influences its success. This study aimed to compare the effectiveness and safety of ultrasonic-with-ballistic lithotripsy (hereafter the combined device) and pneumatic lithotripsy during PCNL in a tertiary-care hospital in Bangladesh. Methods In this prospective, non-randomized quasi-experimental study, 52 adults aged 18-70 years with renal calculi 2-4 cm in size who underwent PCNL between January 2022 and December 2022 were enrolled and allocated to ultrasonic-with-ballistic lithotripsy (Group 1, n=26) or pneumatic lithotripsy (Group 2, n=26). The first patient was allocated by lottery and every subsequent patient alternately, so allocation was quasi-random and not concealed. The prespecified primary outcome was the stone-free rate on plain kidney-ureter-bladder radiography at four weeks, defined as no residual fragment or a single non-obstructing fragment smaller than 4 mm. Secondary outcomes were stone disintegration (fragmentation-and-extraction) time, total operative time, perioperative Hb drop, blood transfusion, complications and length of hospital stay. Postoperative complications were graded via the modified Clavien-Dindo classification. Categorical and continuous variables were compared via the chi-square test, Fisher's exact test and Student's t test; effect estimates are presented with 95% confidence intervals, and p<0.05 was considered statistically significant. Results The demographic and stone characteristics of the two groups were similar, although mean stone size was 2.4 mm smaller in Group 1 (p=0.068). The stone-free rate was significantly greater in Group 1 (25/26 (96.2%) versus 19/26 (73.1%); risk difference 23.1%, 95% CI 3.0% to 42.5%; relative risk 1.32, 95% CI 1.03 to 1.68; Fisher exact p=0.049). Stone disintegration time (22.1±5.9 versus 28.9±8.6 minutes; mean difference -6.8 minutes, 95% CI -10.9 to -2.7; p=0.002) and total operative time (57.7±15.6 versus 86.2±13.9 minutes; mean difference -28.5 minutes, 95% CI -36.7 to -20.3; p<0.001) were significantly shorter in Group 1. In contrast, the mean Hb drop (1.4±0.4 versus 1.6±0.5 g/dL; p=0.118), blood transfusion requirement (9/26 (34.6%) versus 12/26 (46.2%); p=0.397), postoperative fever (4/26 (15.4%) versus 3/26 (11.5%); p=0.668), overall complications, and length of hospital stay did not differ significantly between the groups. Conclusions Ultrasonic-with-ballistic lithotripsy was associated with a higher radiographically defined stone-free rate and with shorter disintegration and total operative times than pneumatic lithotripsy, and no statistically significant difference in the observed complications or in hospital stay was detected. Because allocation was not randomized, the sample was small, stone-free status was assessed radiographically rather than tomographically, and no cost analysis was undertaken, these findings describe an association rather than a causal effect and do not establish equivalence in safety. Adequately powered multicenter randomized trials with computed tomography-based stone-free assessment and formal cost-effectiveness evaluation are needed before routine adoption in resource-limited settings can be recommended.