Can Women Accurately Predict Their Voided Volumes?

Voiding diaries can be onerous, we sought to investigate if some women can predict their voided volumes.

The objective of this study is to determine the accuracy of estimated voided volumes and characteristics most predictive of accuracy.

We prospectively collected data on 101 women undergoing urodynamics for lower urinary tract symptoms and/or prolapse at a tertiary care facility. Data collection included postvoid residual volume, urodynamic diagnosis, flow time and rate, and a 1-time measurement of voided volume into a blinded uroflow. Linear and logistic regression analyses were performed to examine predictors of estimated voided volume (mL).

Mean age was 58.2 years (standard deviation, 12.8 years). The median estimated voided volume and actual voided volume were 240 and 215 mL, respectively. The average percent error was 15% (63% of patients being within a 30% margin of error and 32.7% being within a 20% margin of error). On linear regression analysis, smaller voids of 101 to 200 mL were associated with greater accuracy (R2 = 0.37 P = 0.001) and diagnosis of anxiety was associated with a higher voided volume percent error (P = 0.028). Logistic regression analysis revealed that for every 1 year increase in age, there was a 3% decrease in odds of predicting voiding volume within 30% (odds ratios, 0.97; P = 0.041).

Nearly two-thirds of women estimated their voided volume within 30% of the actual void and one-third of women could predict within 20%. This should be taken into consideration when obtaining patient history, particularly with age and diagnosis of anxiety, and may substantiate use of voiding diaries for accurate measurement in specific populations.