Impact of urethral catheterization on uroflow during pressure-flow study

Objective To investigate the impact of urethral catheterization on uroflow by comparing urodynamic parameters of free uroflowmetry versus pressure-flow study in adult patients with benign prostatic hyperplasia, female stress incontinence, lumbosacral spinal injury or spina bifida. Methods Each patient was required to perform pressure-flow study immediately following free uroflowmetry. Maximum flow rate (Qmax), average flow rate (Qave), voided volume (VV), Tmax (time to Qmax) and post-voiding residual urine (PVR) were compared between the two tests. Results Out of 120 patients, transurethral catheterization significantly impacted uroflow. In male patients with benign prostatic hyperplasia ( n = 50), Qmax, Qave and Tmax were significantly different between free uroflow and pressure-flow study. In patients with female stress incontinence ( n = 30), there were no statistically significant between-test differences in VV and Tmax, but Qmax, Qave and PVR were significantly different. In patients with spinal injury or spina bifida ( n = 40), Qmax, Qave and VV were significantly different between free uroflow and pressure-flow study. Conclusion Urethral catheterization adversely impacts uroflow in patients with benign prostatic hyperplasia, female stress incontinence, spinal injury or spina bifida. Free uroflowmetry should be performed before pressure-flow study.