[Usefulness of uroflowmetry for postoperative monitoring of boys with hypospadia].

Uroflowmetry is a non-invasive diagnostic method well accepted by children and uninfluenced by stress. It allows the study of natural urination and could significantly reduce the frequency of calibration and postoperative urethral dilation (invasive, poorly tolerated procedures) in hypospadias. However, the usefulness of uroflowmetry in children has been questioned. The aim of this study was: (1) to assess the repeatability of uroflowmetry and the objectiveness/reliability of the procedure in children; (2) to check whether uroflowmetry could replace urethral calibration for postoperative monitoring of patients with hypospadia. Preoperative and postoperative uroflowmetric investigations and urethral calibrations were performed in 54 boys aged 5-14 years (Table 1) forming the study group (GB) (360 uroflowmetric measurements in total). The results were compared with uroflowmetry results in 26 boys of the same age from the control group (GK) (102 measurements in total). To measure the rate at which urine passes through the urethra, the author constructed a simple apparatus (basing on the apparatus for adult patients used by Janosz) (Fig. 1). For urethral calibration, metal bougies manufactured by PennTM were used. Documentation consisted of data sheets which were next computer processed (Fig. 2). The preoperative and postoperative results of uroflowmetry (voiding time, total volume voided, average flow rate, maximal flow rate, voiding time for first 100 mL of urine, average flow rate during first 10 s) were compared for each patient. Next, the results in the study group were compared with age-matched controls (Tables 2-5, Fig. 3) and with urethral calibration values (Table 6; Fig. 9). 462 urination curves (360 from the studied group and 102 from the control group) were examined and 6 curve shapes were recognized (Fig. 4). Graphical analysis of individual urination curves in the study and control groups was done to evaluate the repeatability of the method (Fig. 5). Statistical and graphical analysis of 4 uroflowmetric parameters (average flow, maximal flow, voiding time for first 100 mL of urine, average flow rate during first 10 s) were compared with mean values and standard deviation in the age subgroups of the study and control groups (Fig. 6) and with urethral calibration values in the study group (Fig. 7). Correlation between maximal flow rate and urethral calibration after surgery was checked (Fig. 8). Maximal flow rate correlated with the corresponding urethral calibration value (Table 6; Fig. 9). The homogenous clinical material (boys with hypospadias) allowed the evaluation of the uroflowmeter as to precision and repeatability. The apparatus proved reliable and facilitated the preoperative evaluation and postoperative monitoring in hypospadias. The following conclusions were drawn: (1) Uroflowmetry is an objective, reliable and repeatable investigation in children; (2) Uroflowmetry could replace urethral calibration for postoperative monitoring of hypospadia patients.