A study to establish normal reference values of urine flow parameters in healthy South African females

Abstract

BACKGROUND. Several studies have demonstrated the negative impact of lower urinary tract symptoms on health-related quality of life domains. Uroflowmetry is a simple screening test performed after taking a detailed history and examination of the patient. However, unlike men, there are no universally accepted and population-specific uroflow nomograms available for women. OBJECTIVE. To determine the normal reference values for various uroflow parameters in a healthy female South African population and to determine ethnic variations in measured parameters. METHODS. This was a cross-sectional study done at a tertiary hospital in Pretoria. Recruited females included healthy staff members, students, patients, and their relatives who attended the gynaecology outpatient department. Quantile regression was used to formulate uroflow centiles using average and maximum urine flow rate over voided volume. RESULTS. We recruited 336 females out of 353 volunteers (n=306 for study group and n=30 for control group). The mean (standard deviation (SD)) age was 35.15 (10.24) years, voided volume 179.71 (136.10) mL, voiding time (26.13 (19.48) s), time to maximum flow rate (Qmax) (5.85 (4.19) s), Qmax (20.01 (9.67) mL/s) and average flow rate (Qave) (10.16 (5.40) mL/s). Confidence limit flow-volume nomograms were developed, and these were validated against asymptomatic women (n=30). Black females (n=255) had statistically significantly higher average urine flow rate (p=0.023) than white females (n=55). CONCLUSION. The generated nomograms in healthy women add to current scientific literature on this topic. Potential ethnic variation in uroflowmetry parameters needs further exploration.