Urine flow acceleration in healthy children: A retrospective cohort study

Abstract PURPOSE: To establish normal reference values of urine flow acceleration (Qacc) in healthy children, as there is a lack of nomograms for normative reference values of Qacc by voided volumes in paediatric population so far. Qacc might be an early indicator of autonomic neuropathy in children and adolescents. METHODS: Data were retrospectively collected from healthy children who underwent uroflowmetry between 1990–­1992. Exclusion criteria were voided volume less than 20 mL, postvoid residual more than 15%, and signs of an overstretched bladder. Baseline characteristics and uroflowmetry parameters were collected from girls and boys based on their body surface measurements (<0.92 m2; 0.92–1.42 m2; and >1.42 m2). Voided volume, voiding time, time to maximum flow rate, maximum and average flow rates of urine were measured, Qacc was calculated. Postvoid bladder diameter was measured by ultrasonography and converted to volume. RESULTS: Uroflowmetry parameters of 208 children (≤18 years old, 45.2% girls, mean age 9.68 ± 3.09 years) who performed 404 micturition were analysed. Median voided volume was 130 [20–460] mL, median voiding time was 10 [3–56] sec, median time to Qmax was 3 [1–14] sec, median Qave was 11.7 [2.5–36.6] mL/sec, median Qmax was 20.5 [5–50] mL/sec, median Qacc was 6 [0.81–25] mL/sec2, and median postvoid residual volume was 1.83 [0–38.62] mL in the total population. Qacc nomograms were given in centile forms for girls and boys separately which show an inversely proportional correlation between voided volumes.CONCLUSION: These are the first nomograms for normative reference values of Qacc in paediatric population (girls and boys separately) by voided volumes in centile forms. These may be useful to interpret abnormal Qacc values, and diagnose lower urinary tract diseases over a wide range of voided volumes.