Indirect signs of infravesical obstruction on voiding cystourethrography improve post-neonatal posterior urethral valves detection rate.

• Worldwide agreement is that a non-dilated urethra on voiding cystourethrography excludes obstruction. • Half of patients with posterior urethral valves have non-dilated urethra on voiding cystourethrography. • Accounting for indirect signs of posterior urethral valves on voiding cystourethrography improves the diagnostic performance.