Vagina

The vagina is a midline fibromuscular tubular organ positioned in the female perineum extending superiorly from the vulva, to the cervix and uterus in the pelvis.

Gross anatomy

The vagina is 8-10 cm in length, extending posterosuperior from the vestibule through the urogenital diaphragm to the uterus. The vagina forms a 90° angle with the uterus.

The vagina includes the following parts:

  • vaginal orifice, incompletely covered by the hymen
  • vault: upper end of the vagina
  • fornices (anterior, posterior, lateral): recesses formed as the vagina surrounds the cervix

The anterior and posterior vaginal walls are usually closely apposed, diverging at the vaginal vault and fornices. The posterior fornix is covered by the peritoneum of the anterior part of the rectouterine pouch.

The vagina is supported by various structures:

After menopause, the vagina shortens in length and the fornices almost completely disappear.

Relations

Arterial supply

Venous drainage

Lymphatic drainage

Innervation

  • upper vagina: includes both parasympathetic and sympathetic innervation
    • sympathetic fibers from the hypogastric plexus supply blood vessels and smooth muscle of the vaginal wall
    • afferent fibers run with sympathetic nerves
  • lower 2-3 cm vagina: perineal and posterior labial branches of the pudendal nerve, anterior part of the vulva from the ilioinguinal nerve

Histology

Three layers:

  • mucosa (non-keratinized stratified squamous epithelium): is hormonally sensitive, and lubricated from the Cervical and Bartholin's glands
  • muscularis: connective tissue and smooth muscle (outer longitudinal and inner circular)
  • adventitia: endopelvic fascia that connects the vagina to surrounding pelvic structures to maintain support
  • Embryology

    Embryological derivation of the vagina is from two parts, which is important for understanding the origin of congenital anomalies:

    • upper two-thirds of the vagina, cervix and uterus: all derived from the paired Mullerian / paramesonephric ducts.
    • lower one-third of the vagina: derived from the bilateral sinovaginal bulbs which arise from the urogenital sinus

    Radiographic features

    Ultrasound

    During transabdominal (TA) scanning the distended bladder, which acts as an acoustic window, does not affect vaginal position. The vagina can, therefore, be used as an effective landmark, even if the uterus does not occupy its familiar position in the pelvis. The vagina is best seen with a midsagittal TA approach, with a partially-filled bladder. The vagina is hypoechoic and the mucosa is echogenic. The echogenicity of the mucosa diminishes in menopause, with the loss of estrogen stimulation.

    Related pathology