Urine flow acceleration in healthy children: A retrospective cohort study

To establish normal reference values of urine flow acceleration (Q_acc ) in healthy children, as there is a lack of nomograms for normative reference values of Q_acc by voided volumes in the pediatric population so far. Q_acc might be an early indicator of autonomic neuropathy in children and adolescents.

Data were retrospectively collected from healthy children who underwent uroflowmetry between 1990 and 1992. Exclusion criteria were voided volume less than 20 ml, and postvoid residual more than 15%. Baseline characteristics and uroflowmetry parameters were collected from girls and boys aged between 6 and 18 years. Voided volume, voiding time, time to maximum flow rate, and maximum and average flow rates of urine were measured, and Q_acc was calculated. Postvoid bladder diameter was measured by ultrasonography and converted to volume.

Uroflowmetry parameters of 208 children (≤18 years old, 45.2% girls, mean age 9.68 ± 3.09 years) who performed 404 micturition were analyzed. Median voided volume, voiding time, time to Q_max , Q_ave , Q_max , Q_acc , and postvoid residual volume were 130 [20-460] ml, 10 [3-56] s, 3 [1-14] s, 11.7 [2.5-36.6] ml/s, 20.5 [5-50] ml/s, 6 [0.81-25] ml/s² , and 1.83 [0-38.62] ml, respectively. Q_acc nomograms were given in centile forms for girls and boys separately, which show an inversely proportional correlation between voided volumes.

These are the first nomograms for normative reference values of Q_acc in the pediatric population (girls and boys separately) by voided volumes in centile forms. These may be useful to interpret abnormal Q_acc values and diagnose lower urinary tract diseases over a wide range of voided volumes.