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Cervix of uterus

The cervix of the uterus is the lower cylindrical part of the uterus that projects into the vagina. It forms the connection between the uterine cavity and the vaginal canal through the cervical canal. The cervix plays essential roles in reproduction, menstruation, and childbirth, and is a key structure in gynecologic imaging and oncology.

Synonyms

  • Uterine cervix

  • Cervical canal of uterus

  • Neck of uterus

Parts

  • Supravaginal part: The portion above the vagina, related to the bladder and rectum

  • Vaginal part (ectocervix): Projects into the upper vagina and is visible on speculum examination

  • Cervical canal (endocervical canal): Passage connecting uterine cavity to vagina, bounded by the internal os (superior) and external os (inferior)

Relations

  • Anteriorly: Bladder and anterior vaginal fornix

  • Posteriorly: Rectum and posterior vaginal fornix

  • Laterally: Broad ligament, ureters, and uterine vessels

  • Inferiorly: Vagina

  • Superiorly: Uterine body

Function

  • Serves as a passage for sperm to enter the uterine cavity

  • Provides a barrier through the cervical mucus, which changes consistency during the menstrual cycle

  • Dilates during labor to allow passage of the fetus

  • Protects the upper genital tract from ascending infection

Clinical Significance

  • Common site of precancerous and cancerous changes (cervical intraepithelial neoplasia, cervical carcinoma)

  • Assessed during Pap smear and colposcopy for early detection of cancer

  • Cervical incompetence may lead to second-trimester pregnancy loss or preterm birth

  • Affected in infections (cervicitis, HPV-related lesions)

  • Key landmark in gynecological surgery and imaging

MRI Appearance

T1-weighted images:

  • Cervical stroma shows low signal intensity

  • Endocervical canal mucosa shows slightly higher signal intensity

  • Fatty tissue around cervix shows high signal, providing contrast

T2-weighted images:

  • Cervical stroma shows low signal intensity (dark) due to dense fibrous tissue

  • Endocervical mucosa and canal appear bright (high signal)

  • Useful for evaluating tumors, which disrupt the normal low-signal stroma

STIR (Short Tau Inversion Recovery):

  • Stroma appears dark

  • Inflammation, edema, or tumor infiltration appears bright

T1 Fat-Sat Post-Contrast:

  • Normal cervix enhances mildly and uniformly

  • Malignant lesions enhance early and irregularly

  • Inflammatory changes show diffuse or focal enhancement

CT Appearance

Non-Contrast CT:

  • Cervix appears as a soft tissue density structure at the uterovaginal junction

  • Poor differentiation from the uterus without contrast

  • Calcifications may indicate chronic inflammation or cervical fibroid

Post-Contrast CT:

  • Cervical tissue enhances homogeneously in normal state

  • Tumors appear as bulky or irregularly enhancing masses

  • Inflammatory lesions may show heterogeneous enhancement

  • Abscesses show central low attenuation with peripheral rim enhancement

MRI image

cervix of uterus MRI sagittal image anatomy image-img-00000-00000

CT image

cervix of uterus CT sagittal image anatomy image-img-00000-00000