Large voided volume suggestive of abnormal uroflow pattern and elevated post-void residual urine.

AIM

To report the cut-off value for large voided volume (LVV) suggestive of abnormal uroflow pattern or elevated post-void residual urine (PVR) in healthy kindergarteners.

METHODS

From 2003 through 2008, we enrolled 417 healthy kindergarten children for evaluation of uroflowmetry tests and PVR. The uroflowmetry curves were interpreted if voided volumes (VV) were >50 ml, and categorized as bell-shaped, staccato, plateau, and interrupted. Only bell-shaped curves were categorized as normal. After 2006, PVR was assessed within 5 min after each voiding with a VV >50 ml. A PVR >20 ml is regarded as elevated. Receiver operative characteristic (ROC) curves were constructed to evaluate the cut-off value of VV/expected bladder capacity (EBC) with regard to nonbell-shaped uroflowmetry curves, and/or elevated PVR.

RESULTS

Of 385 children (mean age: 4.85 ± 0.96 years), 699 uroflowmetry, and 556 PVR data were eligible for analysis. There were 502 (71.8%) bell-shaped, 76 (10.9%) plateau, 102 (14.6%) staccato, and 19 (2.7%) interrupted curves. Mean and median PVR were 12.4 ± 21.2 and 5.5 ml, respectively. Of 556 PVRs, 96 (17.3%) were >20 ml. Based on the ROC curve for the nonbell-shaped curves and/or elevated PVR, VV >100% EBC was best defined as LVV. There were statistically more elevated PVR, and more nonbell-shaped curves in the voidings with than without LVV. There is a trend that peak flow rate decreased when VV was >150% EBC.

CONCLUSIONS

VV of more than 100% EBC can be defined as LVV which was associated with higher rates of abnormal uroflow pattern and/or elevated PVR.