Endocrine Abstracts

Based on the traditional belief that the lower vagina does not form owing to excess androgens in utero, extensive dissections are undertaken to bring the vagina down to the skin level in 46XX CAH individuals. However, long held knowledge about the embryological origins of the lower vagina and the key role of androgens has been questioned by genetic and molecular studies [Cai Y. 2009. https://doi.org/10.1387/ijdb.082846yc ]. Our aim was to assess the level of the vaginal introitus (VI) in relation to the perineal body (PB) in 46 XX CAH.

Methods: Urogenital anatomy was prospectively studied during feminising genitoplasty in all consecutive 46XX CAH subjects by the first author from January 2003 to June 2023. Lengths of clitoris, common channel (CC), vagina and urethra were measured. Level of the VI in relation to the PB and presence of hymen were checked. Patients were categorised by appearance of the CC and VI: Type 1 - CC bifurcating to urethra and vagina; type 2 - CC was indistinguishable from a male urethra and VI was found at the ‘verumontanum’, sometimes with difficulty.

Results: 38 patients were included: 18% were Prader 5 and 76% were Prader 3 or 4. Median age at surgery was 20 months (range 4 months to 16 years). Median vaginal length was 45mm (range 35-65mm) and 89% had a hymen. Age adjusted urethral length was only 3mm shorter in Type 2 than Type 1 (P=0.017). Division of fused labial and genital folds was sufficient to expose the VI just in front of PB in all patients. In Type 2 patients, bulbo-spongiosus muscle had to be opened back to the PB and narrow VI had to be opened posteriorly for about 5mm. None required urogenital sinus mobilisation.

Conclusion: In all patients with 46 XX classical CAH, the whole vagina is present, the VI is located at the normal position at the level of the perineal body, and potentially harmful vaginal mobilization is not required. This study provides further evidence that the whole vagina is derived from Mullerian ducts and the role of androgen deficiency on formation of the vagina is a myth.