Purpose or Case Report: Congenital urethral anomalies comprise a wide spectrum of developmental disorders. Conventional imaging such as contrast voiding cystourethrography (VCUG) and retrograde urethrography (RGU) are still the first radiological investigations for diagnosis, pre-operative planning based on visualization of urogenital anatomy, and postoperative follow-up.
An understanding of the embryological origin of the urogenital tract is essential for the radiologist to correctly diagnose urethral anomalies. Urogenital sinus is the precursor of bladder, female urethra and posterior urethra in males, which is separated from the hindgut by the urorectal septum. A defect in this septum can give rise to a myriad of anorectal malformations. The anterior urethra in males is derived from fusion of the ventral urethral folds. Any abnormality in proliferation, fusion or canalisation of these embryological structures leads to various congenital anomalies.
Sterile technique and periprocedural antibiotics are essential to avoid introducing or exacerbating urinary tract infection, which can be catastrophic in a child with reflux or bladder outlet obstruction. RGU is typically performed prior to a VCUG.The urethra is cannulated and an iodinated contrast agent such as urografin is injected under fluoroscopic guidance for the evaluation of anterior urethra. The bladder is then catheterised and filled to age-appropriate capacity. The child is allowed to micturate after removal of the catheter to obtain voiding films for evaluation of posterior urethra, and vesicoureteral reflux. A post-void film to look for residual contrast in the bladder completes the study.
In this exhibit, after a review of the embryology and anatomy of the urogenital system, we describe the technique, indications and contraindications of conventional urethrography. This will be followed by a discussion of clinicoradiological features of urethral pathologies in children, including urethral valves, diverticula, megalourethra, Mullerian remnants, persistent cloaca, and syndromic conditions such as Prune belly syndrome. Normal variants and imaging pitfalls will also be discussed.
Conventional urethrography is an age-old, yet simple and useful technique for the evaluation of the pediatric urogenital tract. We revisit this technique and describe its utility in diagnosis and follow-up of urethral anomalies in children.
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