Login to Access Video or Poster Abstract: MP31-06
Sources of Funding: Institute for Bladder and Prostate Research

Introduction

For research purposes, most authorities agree that it is necessary to measure the time and amount of each void for at least a 24 hour period using a frequency volume chart (FVC). However in clinical practice, the FVC is often omitted. Certain diagnoses - polyuria (P), oliguria (O), nocturnal polyuria (NP), and small/large bladder capacity (SBC, LBC) - can only be diagnosed by a FVC. The purpose of this study is to estimate the prevalence of these conditions based on the FVC.

Methods

This is a retrospective multicenter observational study of consecutive patients evaluated for lower urinary tract symptoms (LUTS) who completed a 24h bladder diary. When multiple diaries were completed, the earliest was used. There were no other exclusions. A contemporaneous uroflow voided volume (UVV) was collected for each patient after they were instructed to drink until their bladder felt full. The following data was recorded for each patient: maximum voided volume (MVV), 24 hour voided volume (24HV), and nocturnal polyuria index (NPi). Corresponding diagnoses were derived as follows: O (24HV < 1L); normal (24HV=1-3 L); P (24HV > 3 L); NP (NPi > .33); SBC (MVV <150 mL); LBC (MVV > 600 mL). Spearman correlation was calculated between UVV and MVV.

Results

There were 643 patients, 407 male and 236 female. Prevalence of FVC-derived conditions in this population is seen in table 1. The correlation between UVV and MVV is seen in the plot. The MVV was an average of 116 mL greater than the UVV.

Conclusions

P, O, NP, LBC and SBC are not uncommon in patients with LUTS; nearly a third of patients had either O or P and 20% had NP. Whether or not these data possess external validity, they demonstrate that without measurement of voided volumes during a FVC it is difficult or impossible to diagnose these conditions. Further, there is only a weak correlation between UVV measurements and MVV obtained by FVC, so one should be cautious about interpreting the results of a single uroflow.

Funding

Institute for Bladder and Prostate Research