Title: Diameter of the External Urethral Sphincter as a Predictor of Detrusor-Sphincter Incoordination in Children: Comparative Study of Voiding Cystourethrography
Abstract: Purpose: Voiding cystourethrography (VCUG) is one of diagnostic procedures widely used to evaluate lower urinary tract abnormalities in children.For children with or without suspected voiding dysfunction, we measured the internal diameter of the external urethral sphincter (EUSD) on VCUG to evaluate its diagnostic accuracy as a predictor of detrusor-sphincter incoordination. Materials and Methods:(Part 1) Ninety-six children (59 boys and 37 girls) with normal voiding function underwent VCUG.In each child, 1 to 6 VCUGs (mean 2.1) were performed as a part of urological evaluations.Thus, a total of 200 VCUGs were collected.Underlying urological disease was primary vesicoureteral reflux in 57, congenital hydronephrosis in 9, urinary tract infection in 6, ureteral anomalies in 11, and others in 13.For the determination of EUSD in a given VCUG, EUSD was measured in consecutive films and the widest EUSD was chosen.(Part 2) Forty-three children with suspected voiding dysfunction underwent VCUG and sphincter electromyography (EUS-EMG).The findings of EUS-EMG were comparatively analyzed with EUSD.Results: (Part 1) Age-dependent increase in EUSD was seen in children with normal voiding function.EUSD (mm) was formulated as 0.166 x age (years) + 4.31 for boys (p=0.0001,r=0.374), and 0.222 x age (years) + 2.73 for girls (p<0.0001,r=0.595).Overall incidence of EUSD less than 3 mm was only 4% (8/200).(Part 2) EUS-EMG documented detrusor-sphincter incoordination in 15 children (35%).When we defined EUSD less than 3mm as a cut-off value for predicting detrusor-sphincter incoordination, the sensitivity, specificity, positive and negative predictive values were 93%, 89%, 82% and 96%, respectively.Conclusions: EUSD has a satisfactory sensitivity and specificity as a predictor of