Urinary flow measurement in hypospadias correlated to surgical procedure and risk of development of urethra-cutaneous fistula.

AIM: To explore the correlation between fistula development and urinary flow measurements after hypospadias repair with emphasis on patients with urethrocutaneous fistula complications and to identify risk factors for fistula development. METHODS: Urinary flow was examined in boys operated on for hypospadias. Outcome of maximum urinary flow (ml/s) (Qmax), voided volume for age (ml) (Volume), and pathological flow pattern (n) (Curve) was compared between the Byars, Mathieu, and Tubularized Incised Plate (TIP) surgical repair methods and between the groups of those who had and had not developed a fistula. Logistic regression analysis was performed for age at operation, genetics, comorbidity, or urinary flow measurements regarding the development of urethrocutaneous fistula. RESULTS: Seventy-three boys underwent hypospadias repair. Overall, the urinary flow measurements differed significantly between the three reconstructive methods, being favorable for the Mathieu procedure regarding Qmax (p < 0.01), volume (p = 0.04), and frequency of pathological voiding curve (p < 0.01; Table). The frequency of urethrocutaneous fistula was 18% (13/73) and did not differ significantly between the three different reconstructive surgery methods (Byar 33%, Mathieu 32%, and TIP 12%; p = 0.22). Urinary flow measurements did not differ between patients with and without fistula complications regarding Qmax 10 ml/s (4-16) vs. 8 ml/s (2-18), voided volume 74 ml (35-171) vs. 71 ml (9-270), or abnormal urinary flow pattern (23% vs. 30%). On logistic regression analysis, age at operation, genetics, comorbidity, and urinary flow measurement parameters did not turn out to be independent risk factors for development of urethrocutaneous fistula after hypospadias repair. DISCUSSIONS: The study demonstrated significant differences between the urinary flow measurement results between the three different repair methods, favoring the Mathieu procedure. A low Qmax was a common postoperative finding. Urinary flow measurements did not differ between boys developing fistula and those who did not. No risk factors for fistula development were identified. The study did not support that it would be possible, at an early postoperative stage, to identify those with an upcoming postoperative fistula neither with urinary flow measurements nor through risk factors. No similar reports have studied the possibility of using postoperative urinary flow measurements to determine patients at risk of fistula development after hypospadias repair. CONCLUSIONS: Urinary flow measurements were favorable after hypospadias reconstruction with Mathieu compared with Byars and TIP. Furthermore, urinary flow measurements did not differ between reconstructed with and without a fistula complication. No risk factor for fistula development was identified.