Postvoidal residual urine is the most significant non-invasive diagnostic test to predict the treatment outcome in children with non-neurogenic lower urinary tract dysfunction.
INTRODUCTION
Uroflowmetry (UF) alone is often inadequate or unreliable to diagnose lower urinary tract dysfunction (LUTD). Therefore, other non-invasive tests, such as ultrasound (US), post-voiding residual volume (PVR) assessment and symptom scales, are used as well for objective definition of the problem.


OBJECTIVE
The aim of this study was to investigate the possible predictive function of the non-invasive diagnostic tests for the response to treatment.


STUDY DESIGN
The prospective registry data of 240 patients with LUTD, from November 2006 to September 2013, were retrospectively analyzed. All patients were aged 5-14 years old. Patients with a previous diagnosis of vesicoureteral reflux (VUR), neurogenic bladder, monosymptomatic nocturnal enuresis (NE) were excluded from the study. Uroflowmetry, US, PVR and the Dysfunctional Voiding and Incontinence Symptom Scale (DVISS) were performed on every patient at their first visit and follow-ups. A DVISS <9 was considered as the DVISS response; parental opinion was based on International Continence Society criteria of clinical response. Time passed until clinical response was the last outcome parameter.


RESULTS
Mean age was 8.2 years. Median follow-up was 60.5 months. A total of 62% of patients had complete response, 28.1% had partial response, and 9.7% had no response. Demographic variables were not associated with clinical outcome. Co-existing enuresis nocturna, multiple pharmacotherapy, and increased DVISS were associated with longer time until clinical response. Post-voiding residual volume assessment was the only test to have a prognostic value.


DISCUSSION
Resolution rates of LUTD ranged from 40 to 90%. High resolution rate could be attributed to the long follow-up period, and the chance of spontaneous resolution. Treatment modalities and co-existing NE were associated with longer time until clinical response. Only PVR was associated with prognosis. This was the first study in literature to report such findings. It was seen that the normalization of pathologic patterns was a good sign for treatment success. The DVISS results showed significantly higher rates of incontinence compared to initial symptoms defined by the patients and/or their parents. This showed the importance of using scoring systems to better define the severity of symptoms. It was hard to establish a standardized cut-off value for bladder wall thickness on US. However, US was a good test for diagnosing additional pathologies.


CONCLUSION
Increased PVR was the single tool that was associated with prognosis and, therefore, should always be performed after UF. In addition, DVISS can help parents be counseled about their treatment expectations.