LAUSR

Purpose To identify urodynamic factors associated with the mechanical stop test and immediate spontaneous voiding following transurethral resection of prostate (TURP). Methods We identified 90 men who underwent TURP over a 12-month period. Forty-three (mean age 68 years) underwent urodynamic evaluation prior to TURP. Isovolumetric detrusor contractile pressure ( P iso ) was obtained using the mechanical stop test during the voiding phase, and used to calculate detrusor contractile reserve ( P res  =  P iso − P det @ Q max ). Primary outcome was spontaneous voiding after TURP. Results Preoperative catheter-free spontaneous voiding was present in 63% of men (27/43) with a urodynamic (mean ± SD): Q max 6.2 ± 2.7 mL/s, P det @ Q max 102 ± 47 cmH 2 O, P iso 124 ± 49 cmH 2 O, P res 22 ± 16 cmH 2 O, 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): Q max 3.6 ± 3.3 mL/s, P det @ Q max 87 ± 38 cmH 2 O, P iso 99 ± 51 cmH 2 O, P res 10 ± 18 cmH 2 O, 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 ( P det @ Q max , P iso , P res , BOOI and BCI), only P res was significantly associated with immediate spontaneous voiding after TURP (threshold P res  ≥ 9 cmH 2 O, AUC = 0.681, p  = 0.035). Conclusions In men who underwent TURP, a P res  ≥ 9 cmH 2 O was associated with immediate spontaneous voiding and may be easily incorporated into the postoperative pathway.