Post-void residual urine under 150 ml does not exclude voiding dysfunction in women.

INTRODUCTION AND HYPOTHESIS: It has been claimed that post-void residual urine (PVR) below 150 ml rules out voiding dysfunction in women with stress urinary incontinence (SUI) and provides license to perform sling surgery. The cut-off of 150 ml seems arbitrary, not evidence-based, and so we sought to investigate the ability of PVR < 150 ml to exclude voiding dysfunction.
METHODS: We retrospectively reviewed the charts of all patients who underwent invasive urodynamics from 1 January 2013 to 31 December 2013. Voiding dysfunction was diagnosed if both the invasive urodynamic and the free flow showed abnormal results. We registered the PVR in patients with voiding dysfunction and divided them into groups with PVR < 150 ml and PVR ≥ 150 ml. Patients were then analyzed for bladder outlet obstruction and detrusor underactivity.
RESULTS: Of the 205 patients undergoing invasive urodynamics in 2013, a total of 20 had voiding dysfunction, 2 with PVR ≥ 150 ml. Eighteen patients had PVR < 150 ml (range 0-50 ml); 9 had bladder outlet obstruction while 7 had detrusor underactivity. Two patients were uncategorized. Out of the 20 patients, 7 had no symptoms or complaints indicating voiding dysfunction.
CONCLUSIONS: Patients with voiding dysfunction often have normal PVR and so PVR < 150 ml cannot exclude voiding dysfunction. All patients should be evaluated using free flow measurements along with PVR to obtain a reliable, objective measurement of their voiding pattern, before anti-incontinence surgery.