Ridley's The Vulva

The clitoris may be absent [63], probably as a result of the genital tubercles remaining hypoplastic or failing to fuse. A penis‐like clitoris in 46,XX DSD is described which is likely to be due to abnormality in the development of the cloacal membrane [64]. Clitoral enlargement occurs in several genetic syndromes (see Chapter 51).

Agenesis of the labia minora and clitoris has been described in isolation [65]. Hypertrophy and/or marked asymmetry of the labia minora may occur without any underlying problem. True hypoplasia of the labia minora occurs infrequently and may be a sign of defective steroidogenesis. Fusion of the labia minora may occur in association with defective sexual differentiation and should not be confused with the superficial labial adhesions seen in the neonatal period or in infancy as a result of an inflammatory condition.

Bilateral renal agenesis is a lethal congenital malformation and in the female is frequently associated with anomalies of the external genitalia, absence of the uterus and vagina, and abnormalities of other systems [66]. Unilateral renal agenesis may be associated with malformations of the external genitalia in up to 40% of cases [67].

The ureteric bud arises from the Wolffian (mesonephric) duct and separates off when the duct is incorporated into the urogenital sinus to form the trigone of the bladder and urethra. Failure of dissociation between the ureteric bud and the Wolffian duct in the female will allow the ureteric orifice to be located at any site along the caudal remnant of the Wolffian duct (Gartner’s duct). Secondary rupture of Gartner’s duct into the vagina [68] allows for vaginal drainage of urine from the ectopic ureter. The most common site for the vaginal opening of an ectopic ureter is the vestibule and usually presents as continuous leakage but has also been mistaken for premature rupture of the membranes in a pregnant patient [69].

If the sub‐umbilical portion of the anterior abdominal wall fails to meet in the midline above the genital tubercles, the anterior bladder wall is partially or completely absent, leading to incomplete or total bladder exstrophy. It is always associated with epispadias and other abnormalities of the external genitalia. The clitoral bodies are bifid, and the mons pubis and labia protrude anteriorly. The vaginal introitus is situated anteriorly and is frequently stenosed. Magnetic resonance imaging can be very helpful in identifying the anatomical abnormalities and is used prior to surgery, which is usually done in stages [70,71]. Most patients require vaginoplasty in the teenage years.

A more severe form of this structural defect is cloacal exstrophy, in which there are defects of the urorectal structures, bladder, and terminal gastrointestinal tract [ 72]. Advances in neonatal surgery can now result in survival rates of up to 100%, and guidelines exist for management which should be undertaken by specialist multidisciplinary teams [ 73].

Failure of the urogenital septum to reach the cloacal membrane leaves the urethra, vagina, and rectum converging into a single channel with a solitary opening on to the perineum.

Congenital abnormalities of the urethra are much less common in females than in males, but duplication of the urethra is a cause of incontinence. The accessory urethra usually arises from the trigone of the bladder and opens onto the anterior wall of the vagina. Mild forms of epispadias may occur in the female, giving rise to disturbance of bladder control and urinary incontinence. The urethral opening lies deep to the mons, and a bifid clitoris is seen [74]. Hypospadias in the female occurs in association with 46,XX DSD. In both epispadias and hypospadias, the female urethra is congenitally short [75]. Meatal stenosis is uncommon in females but can mimic bladder neck obstruction, and urethral cysts of the para‐urethral Skene’s glands can lead to recurrent urinary symptoms. A prolapse of the urethral mucosa occurs only in females [76]. An ectopic ureter may open into the urethra, and any of these urethral abnormalities may present with urinary incontinence, which leads to an irritant contact vulval dermatitis.

A perineal groove is a rare ano‐perineal malformation, but the cause is unclear. It may be due to a failure of the genital folds to fuse or a defect in the urorectal septum. Exposed mucosa extends from the fourchette to the anus and most resolve spontaneously [77]. An imperforate anus or anal stenosis may be associated with a variety of abnormalities of the genital tract and vulva [78]. An ectopic opening of the lower gastrointestinal tract may be found in the vagina or elsewhere in the perineum. When a rectovaginal fistula is formed, there are often urinary tract abnormalities present as well [79].

Turner Syndrome Foundation

www.turnersyndromefoundation.org

Turner Syndrome Support Society

www.tss.org.uk

Turner Syndrome Society of the United States

www.turnersyndrome.org

Disorders of sexual differentiation

www.dsdfamilies.org

MRKH UK

www.mrkh.org.uk

Congenital adrenal hyperplasia

www.livingwithcah.com

Last accessed September 2021.

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