Bladder Stone Recurrence in Patients That Do Not Undergo Outlet Procedures
Bladder stones have been linked to stasis of urine from bladder outlet obstruction (BOO) due to benign prostatic enlargement (BPE). Many of these patients have been found to make kidney stones and have metabolic disturbances on 24-hour urine analysis. Moreover, many bladder stone patients refuse an outlet procedure. We evaluated bladder stone recurrence rates in patients refusing an outlet procedure comparing results between those compliant versus noncompliant with their BPE and stone prevention medical regimens.
A database of patients undergoing bladder stone procedures without an outlet procedure (n=66) from 2012-2017 at a tertiary referral center was retrospectively analyzed to assess for differences in clinical features between individuals who did or did not form recurrent bladder stones (n= 19 vs 47, respectively) with particular attention to compliance with BPE and kidney stone medical regimens.
Mean prostate size, presence of intraprostatic protrusion, post void residual, flow rate, stone burden and follow-up were similar between groups. In the non-recurrent group, 72 % (34/47) were compliant with BPE medications and 71% (5/7) were compliant with stone prevention regimens compared to 63% (12/19) and 39% (5/13) in the recurrent group (p=0.038 and <0.0001). Recurrent bladder stone formers were more likely to be prescribed two or more medications (p = 0.008). Moreover, recurrent stone formers were found to have lower urine volume (1.5 vs 1.99, p = 0.048) and urine pH (5.64 vs 6.04, p = 0.050) (Table 1).
The etiology of bladder stone formation is multifactorial with BOO and metabolic disturbances as major contributors. In patients who do not undergo an outlet procedure, both factors must be addressed and treated accordingly. Prostate size and voiding dynamics do not predict for recurrence; compliance with medical regimens does predict for recurrence.