To determine the efficacy of a combination of simultaneous shock wave lithotripsy (SWL), hydration with controlled inversion therapy compared with SWL with hydration alone in patients with lower pole calyx stones.

Patients with lower pole stones (4-20 mm) were randomized to SWL or SWL with simultaneous inversion therapy (30° head down Trendelenburg position). Standardized shock waves were given to all patients stratified according to stone size. Subsequent standardized shock waves were given to patients with stone fragments determined by plain abdominal radiography and ultrasound by 2 radiologists blinded to treatment at day 1, weeks 2, 4, 12, 24, and at 1 year. The primary endpoint is stone-free rate (SFR) at week 12.

A total of 140 patients were recruited into the study. Patients were comparable with respect to age, sex, race, and stone parameters at baseline. The overall SFR at week 12 was 72% (n = 49 of 68) in patients with SWL and 76% (n = 54 of 71) in SWL with simultaneous inversion at the end of study (P = .591). There was a trend for SFR to improve over time with >80% of patients being stone-free after 1 year in both groups. No significant adverse effects were noted in both groups of patients.

Although not statistically significant, SWL with simultaneous inversion is a valuable adjunct in assisting the passage of lower pole renal stones with a SFR of 76%. In clinical practice, this also translates to a 1.28 times improvement in SFR with no or minimal additional costs.