Vagina and Vulva	349

In cases of congenital vaginal anomalies, MRI provides information about the location, thickness, and type of congenital obstruction, all of which are important factors in surgical planning (Walker et al. 2011; Griffin et al. 2010; López et al. 2005; Junqueira et al. 2009; Troiano and McCarthy 2004).

4.1\ Imperforate Hymen

Imperforate hymen is the commonest congenital anomaly of the female genital tract. It is usually detected after menarche, when the patient presents with cyclic abdominal pain and primary amenorrhea. Imaging is rarely indicated, since the diagnosis is made at clinical examination (Walker et al. 2011).

4.2\ Congenital Vaginal Septa

Congenital vaginal septa, both longitudinal and transverse may occur either in isolation or with other MDAs. These septa appear as thin, hypointense structures on MRI, best detected on T2WI (Walker et al. 2011; Griffin et al. 2010; López et al. 2005).

a

Longitudinal vaginal septa arise either as a failure of lateral fusion of the Müllerian ducts or due to incomplete resorption of the vaginal septum. They are present in 75% of cases of uterine didelphys. A transverse vaginal septum may also be seen, usually in the upper third of the vagina. Longitudinal vaginal septa may go unrecognized, both clinically and radiologically, if no obstruction is present. When obstruction is present, the septum is best delineated on T2WI, which helps differentiate the hypointense septum from the hyperintense intracavitary secretions and blood (Fig. 9) (Walker et al. 2011; Griffin et al. 2010).

A transverse vaginal septum may present in an adolescent girl with primary amenorrhoea, abdominal pain, and an abdominal mass if the septum is complete, or later in life with dyspareunia and dysmenorrhoea, if the septum is ­incomplete. It is not associated with other urological congenital anomalies or MDAs (López et al. 2005). It may occur at any level within the vagina, although it is more often seen at the junction of the upper and middle thirds, or at the junction of the embryologic sinovaginal plate and the fused Müllerian ducts. MRI is the modality of choice for the identification of transverse vaginal septum, providing useful information for

b

Fig. 9  Longitudinal vaginal septum in the context of a uterus bicornuate and bicollis, with right vagina obstructed. (a) Axial fat-suppressed T2WI depicts double

vagina (arrow) (b) Coronal T2WI shows obstructed right vagina (arrowhead) (Courtesy Dr. Forstner R, Salzburg, Austria)