Overnight ambulatory urodynamics (aUDS) is performed as a second-stage test in patients with isolated nocturnal symptoms in whom conventional or video urodynamics have been non-diagnostic. The aims of this study were to determine if a urodynamic diagnosis of detrusor overactivity (DO) or urge urinary incontinence (UUI) on overnight aUDS resulted in a change in patient management and an improvement in their urinary symptoms.

Twenty-five consecutive patients (28% male) having overnight aUDS whose most bothersome urinary symptoms were nocturia and/or nocturnal enuresis seen at our tertiary referral centre between November 1998 and August 2018 were identified from our prospectively acquired database and retrospectively reviewed. Their median age was 38 years (range 18-86). All patients had previously had conventional pressure-flow studies or video UDS (vUDS). aUDS were performed when conventional UDS were non-diagnostic or when the conventional UDS diagnosis was contradictory to the patient's major presenting symptom of nocturia and/or nocturnal enuresis. Six patients were excluded because follow-up data was not available. All conventional UDS, vUDS and overnight aUDS studies were analysed by an experienced urodynamicist and reviewed at a multidisciplinary team (MDT) meeting to ensure accuracy of diagnosis and to determine treatment options. 

Data are expressed as mean ± standard deviation and P-values were calculated using a two-tailed unpaired student t-test for pairwise comparisons of parametric data, unless otherwise stated. Categorical data are expressed as number (percentage) and compared with the Fisher Exact test. A P < 0.05 was considered statistically significant. Analysis was performed using SigmaPlot 12.5 (Systat Software Inc, San Jose CA) statistical analysis package.

Following overnight aUDS all studies were evaluable and a definitive UDS diagnosis of DO was made in 79% (n=19) of 24 patients presenting with nocturia (mean DO pressure 69.1 ± 53.3 cmH2O) and in 90% (n=18) of the 20 patients presenting with nocturnal enuresis. UUI was demonstrated in 80% (n=16) of the 20 patients presenting with nocturnal enuresis. Of the remaining patients, five had a diagnosis of sensory urgency confirmed and one patient was diagnosed with reduced functional capacity due to high PVRs. A change in the primary UDS diagnosis occurred in 80% (n=20) of patients following aUDS.

Nineteen patients had post aUDS follow-up data available for review. DO was demonstrated in 14 of the 15 patients who presented with nocturnal enuresis, and the final patient was found to have reduced functional capacity due to high PVRs. Of the remaining four patients who presented with isolated nocturia symptoms, one patient was found to have DO and the remaining three patients had a diagnosis of sensory urgency confirmed. 

Therefore, 84% (n=16) of this patient sub-group had their clinical diagnosis and management changed following aUDS. In the 15 patients who had DO demonstrated 3 were treated with a clam, 5 were treated with Botox, and the remaining patients were treated with combination medical therapy after refusing Botox/ surgery. Of the three patients with confirmed sensory urgency, one patient was treated with reduced fluid intake, one was treated with desmopressin and the final patient was sent for cognitive behavioural therapy. The patient diagnosed with reduced functional capacity due to high PVRs had their catheterisation technique reviewed by the urology clinical nurses specialist and was advised to catheterise more often.

These treatment changes led to a statistically significant improvement in the reported urinary symptoms of daytime frequency, nocturia and nocturnal enuresis in 79% of patients (Table 1). 61% (11 out of 18) of patients had resolution of their noctuira and 73% (11 out of 15) of patients had resolution of their nocturnal enuresis.

This is the first study to show that overnight aUDS studies demonstrated DO in 79% of patients presenting with nocturia and 90% of patients presenting with nocturnal enuresis. 80% of patients presenting with nocturnal enuresis were also demonstrated to have a diagnosis of UUI. Therefore, the clinical diagnosis and subsequent management pathway were changed in 84% of patients. This resulted in a significant improvement in symptomatic outcomes. 61% of patients had resolution of their noctuira and 73% of patients had resolution of their nocturnal enuresis.