Nocturnal enuresis is an often overlooked complication after robot-assisted radical prostatectomy (RARP). Although many reports have examined daytime urinary incontinence, no reports appear to have focused on nocturnal enuresis after RARP. Several studies have assessed storage dysfunction after RARP. Transient lower urinary tract dysfunction in the form of declines in urethral sphincter function and detrusor overactivity are known to develop independently or compositely to cause postoperative incontinence. The aim of the present study was to elucidate the frequency of nocturnal enuresis, the effects of nocturnal enuresis on quality of life (QOL), and the pathogenic mechanisms of nocturnal enuresis.

Participants in this study comprised 112 consecutive patients who underwent RARP, divided into groups with and without nocturnal enuresis. Nocturnal enuresis was defined as unconscious urination during sleep more than twice a week in the first month after surgery. No patients had experienced nocturnal enuresis before RARP. Uroflowmetry, 1-h pad test, overactive bladder symptom score (OABSS), QOL index, King’s Health questionnaire (KHQ) and Nocturia Quality of Life questionnaire (N-QoL) were evaluated at 1, 3, 6, 9, and 12 months after RARP.

The nocturnal enuresis group comprised 47 of the 112 patients (42%). No significant differences in background characteristics were observed between groups. No significant differences in voided volume or post-void residual urine volume were apparent between groups. The result of OABSS at 1 month after RARP, the OABSS subscores and total score increased and then head for improvement in two groups. OABSS subscores are higher in the nocturnal enuresis group with significant differences; daytime frequency at 1 month after RARP(P=0.029), daytime frequency (P=0.028), urgency (P=0.013), urgency incontinence (P=0.018) and total score(P=0.004) at 3 months after RARP. For KHQ score, Role limitations score (P=0.022), Emotions score (P=0.011), and Symptom severity scale (P=0.017) were all significantly lower in the nocturnal enuresis group. Moreover, N-QOL total score (P=0.010) and subscores for Sleep/Energy (P=0.034) and Bother/Concern (P=0.005) were significantly lower in the nocturnal enuresis group. Multivariate analysis was performed to investigate factors affecting QOL. Nocturnal enuresis, age, body mass index, console time, extracted weight and 1-h pad test were used as independent variables. Dependent variables were N-QOL overall score and KHQ severity measure. Multivariate analysis revealed nocturnal enuresis as a factor significantly affecting N-QOL (P=0.005) and KHQ (P=0.016).

In the early postoperative period, 42% of patients experienced nocturnal enuresis, adversely impacting urinary QOL. The cause of nocturnal enuresis was not decreased bladder capacity or increased residual urine, but was considered to involve overactive bladder (OAB).

Nocturnal enuresis after RARP was associated with urinary QOL. It could be possible to predict a decrease in postoperative QOL by a very simple interview regarding the presence or absence of nocturnal enuresis one month after surgery. OAB after RARP contributes to enuresis, which may therefore be improved with treatment aimed at OAB.