The mechanical stop test and isovolumetric detrusor contractile reserve are associated with immediate spontaneous voiding after transurethral resection of prostate.

Abstract

To identify urodynamic factors associated with the mechanical stop test and immediate spontaneous voiding following transurethral resection of prostate (TURP). We identified 90 men who underwent TURP over a 12-month period. Forty-three (mean age 68years) underwent urodynamic evaluation prior to TURP. Isovolumetric detrusor contractile pressure (Piso) was obtained using the mechanical stop test during the voiding phase, and used to calculate detrusor contractile reserve (Pres = Piso - Pdet@Qmax). Primary outcome was spontaneous voiding after TURP. Preoperative catheter-free spontaneous voiding was present in 63% of men (27/43) with a urodynamic (mean ± SD): Qmax 6.2 ± 2.7mL/s, Pdet@Qmax 102 ± 47 cmH2O, Piso 124 ± 49 cmH2O, Pres 22 ± 16 cmH2O, bladder outlet obstruction index (BOOI) 90 ± 49, and bladder contractility index (BCI) 132 ± 44. The remaining 16 catheter-dependent men demonstrated a urodynamic (mean ± SD): Qmax 3.6 ± 3.3mL/s, Pdet@Qmax 87 ± 38 cmH2O, Piso 99 ± 51 cmH2O, Pres 10 ± 18 cmH2O, BOOI 82 ± 36, and BCI 106 ± 48. Following TURP, 67% of men voided spontaneously with their first void trial, and in receiver operator analysis of urodynamic measures (Pdet@Qmax, Piso, Pres, BOOI and BCI), only Pres was significantly associated with immediate spontaneous voiding after TURP (threshold Pres ≥ 9 cmH2O, AUC = 0.681, p = 0.035). In men who underwent TURP, a Pres ≥ 9 cmH2O was associated with immediate spontaneous voiding and may be easily incorporated into the postoperative pathway.