Preoperative evaluation of the persistent urogenital sinus in cases with congenital adrenal hyperplasia

Background Congenital adrenal hyperplasia (CAH) is a common cause of urogenital sinus (UGS) anomalies. Delineating the abnormal anatomy of the UGS is crucial prior to the operative repair. Genitography and cystourethroscopy are commonly used by most surgeons to plan for reconstruction. We aim at this study to evaluate the role of these modalities and to compare their accuracy in delineating the abnormal anatomy. Methods We did a prospective study of 30 female paediatric patients with persistent UGS secondary to CAH. All cases were evaluated with genitography and cystourethroscopy. We compared the accuracy of each modality in delineating the confluence. The confluence depth, the urethral length proximal to the confluence, the vaginal dimensions, and the depth of the bladder neck were measured in the genitograms. Results Cystourethroscopy showed the abnormal anatomy in all 30 cases (100%). The genitogram showed the site of confluence in 24 cases out of 30 cases (80%). According to the site of the vaginal opening in relation to the external urethral sphincter in the genitogram, we had 2 groups: the low confluence group (N = 14) and the high confluence group (N = 16). The mean confluence depth in the low group was 9.8 mm vs. 20.5 mm in the high group (p-value < 0.001). To find a cutoff point to differentiate low from high groups, we used the values that resulted from dividing the length of the urethra proximal to the confluence over the depth of the bladder neck. By using the ROC curve, the cutoff point was 0.63 mm (< 0.63 mm high, > / = 0.63 mm low) (p-value < .001). Conclusion We recommend using both cystourethroscopy and genitography for preoperative evaluation. Cystourethroscopy is superior in identifying the abnormal anatomy, but it lacks precision in taking measurements. Genitography can avoid this drawback and can precisely measure the confluence depth, vaginal dimensions, and length of the proximal urethra. We suggest using this formula (length of the urethra proximal to the confluence/depth of bladder neck) to classify persistent UGS as low (> / = 0.63 mm) and high (< 0.63 mm).