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Vagina

The vagina is a fibromuscular tubular structure forming part of the female reproductive tract. It extends from the vulva to the cervix of the uterus and serves as the passage for menstrual flow, sexual intercourse, and childbirth. Its wall is composed of muscular and mucosal layers, providing elasticity and strength. The vagina is an important structure in gynecology, obstetrics, and radiology, and its evaluation is crucial in conditions ranging from infections to malignancies.

Synonyms

  • Vaginal canal

  • Birth canal

  • Female genital tract (lower portion)

Location and Structure

  • The vagina lies in the pelvis, directed posterosuperiorly, between the bladder and urethra anteriorly and the rectum posteriorly.

  • It extends from the vaginal vestibule (introitus) to the external os of the cervix.

  • Length: approximately 7–10 cm in adults, with variation based on age, parity, and hormonal status.

  • Walls:

    • Anterior wall: shorter, related to bladder and urethra

    • Posterior wall: longer, related to rectouterine pouch and rectum

  • Layers:

    • Mucosa: non-keratinized stratified squamous epithelium

    • Muscularis: smooth muscle layers

    • Adventitia: connective tissue with vascular plexuses and elastic fibers

Relations

  • Anteriorly: Bladder base and urethra

  • Posteriorly: Rectouterine pouch (Douglas pouch) and rectum

  • Laterally: Levator ani, ureters, pelvic fascia, venous plexuses

  • Superiorly: Cervix and uterus

  • Inferiorly: Opens into the vestibule of vulva between labia minora

Function

  • Serves as the copulatory organ during sexual intercourse

  • Provides a passage for menstrual flow

  • Acts as the birth canal during delivery

  • Maintains microbial balance and immune defense through vaginal flora (e.g., lactobacilli)

Clinical Significance

  • Site of common conditions such as vaginitis, atrophy, congenital anomalies, trauma, and prolapse

  • Primary route for pelvic examination and gynecological procedures

  • Involvement in cancers (vaginal carcinoma, metastasis from cervix/uterus)

  • Imaging plays a role in evaluating masses, fistulas, infections, trauma, and staging of malignancy

MRI Appearance

T1-weighted images:

  • Vaginal wall shows low-to-intermediate signal intensity

  • Vaginal lumen may show high signal if containing blood (e.g., menstruation, hematocolpos) or low signal if collapsed

T2-weighted images:

  • Vaginal wall shows layered appearance: inner mucosa appears hyperintense, muscularis appears hypointense, and adventitia shows intermediate signal

  • Vaginal lumen is hyperintense if distended with fluid

STIR (Short Tau Inversion Recovery):

  • Vaginal wall shows low-to-intermediate signal

  • Pathology (edema, inflammation, tumor infiltration) appears bright hyperintensity

T1 Fat-Sat Post-Contrast:

  • Vaginal wall enhances moderately and uniformly

  • Tumors, infections, or infiltrations show irregular or heterogeneous enhancement

  • Abscess or necrosis demonstrates rim enhancement with non-enhancing central cavity

CT Appearance

Non-Contrast CT:

  • Vagina appears as a soft tissue density tubular structure posterior to the bladder and anterior to the rectum

  • Vaginal lumen may be collapsed, difficult to differentiate without contrast or fluid distension

Post-Contrast CT:

  • Vaginal wall enhances mildly and evenly in normal state

  • Malignant or inflammatory conditions show irregular or asymmetric thickening with heterogeneous enhancement

  • Fistulas or abscesses appear as abnormal low-density tracts or collections with rim enhancement

MRI image

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CT image

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