Reproductive system · Pelvis · Female
Cervix !
The cervix is the narrow lower end of the uterus that opens into the vagina; it stays closed in pregnancy and opens (dilates) in labour.
Official name: Cervix of uterus
Opens in the Durgical app, no sign-up needed.
What it is
The narrow lower end of the uterus that opens into the vagina, with a canal through its middle.
What it does
Stays closed in pregnancy and opens (dilates) in labour; lets menstrual blood out and sperm in.
Key facts
- Where
- Lower third of the uterus; supravaginal part above, vaginal part (portio) projecting into the vaginal vault; cervical canal from internal to external os
- Blood supply
- Cervical (descending) branch of the uterine artery; vaginal artery
- Nerve
- Uterovaginal plexus; pain via pelvic splanchnic nerves (S2–S4)
- Function
- Mucus barrier, closed in pregnancy, dilates in labour; lymph to parametrial, obturator, internal and external iliac and sacral nodes
Relations
- In front
- Supravaginal part: base of the urinary bladder, joined by loose connective tissue (a plane opened in hysterectomy); vaginal part: the shallow anterior fornix
- Behind
- Rectouterine pouch over the supravaginal part and posterior fornix, with the rectum behind; the uterosacral ligament of each side passes back from its posterolateral surface
- Lateral
- Parametrium and cardinal ligament, carrying the uterine artery and uterine veins; the ureters run beneath the uterine artery about 2 cm away on each side
- Above
- Lower uterine segment, at the internal os
- Below
- The vaginal part projects into the top of the vagina, ringed by the vaginal fornix
How to find it
On speculum examination the vaginal part (portio) is seen at the top of the vagina as a smooth pink dome with the external os at its centre. On bimanual examination it feels firm, like the tip of the nose, and serves as the handle to lift the uterus toward the abdominal hand; in pregnancy it feels softer.
Examination
- Cervical motion tenderness: pain when the cervix is moved from side to side on bimanual examination points to irritation of the pelvic peritoneum, as in pelvic inflammatory disease or a ruptured ectopic pregnancy
- Goodell sign: softening of the cervix in early pregnancy; Chadwick sign: bluish colour of the cervix and vagina from congestion
- Bishop score: dilation, effacement, consistency and position of the cervix plus station of the presenting part; a high score means the cervix is favourable for induction of labour
On imaging
Transvaginal ultrasound measures cervical length in pregnancy: a short cervix in the second trimester flags a risk of preterm birth. On T2-weighted MRI the stroma is a dark ring; tumour breaking through it into the surrounding fat means parametrial invasion in cervical cancer staging.
Common problems
- Persistent HPV infection can cause precancerous changes and, over years, cervical cancer.
- Cervical insufficiency (opening too early in pregnancy).
How it is diagnosed
Screening: an HPV test and/or a Pap smear (cytology); colposcopy and biopsy if abnormal.
Treatment
- HPV vaccination prevents most cervical cancers.
- Precancer is removed with a small procedure (LEEP/cone).
Clinical notes
- Cervical cancer spreads sideways through the parametrium toward the pelvic side wall; blockage of the ureters with hydronephrosis marks advanced disease
- In hysterectomy the uterine vessels are clamped close to the cervix, keeping the clamps away from the ureters that pass just lateral to it
- Cervical insufficiency can be treated with a cerclage, a purse-string stitch placed around the cervix during pregnancy
Anatomical variants
- Nabothian cysts: small mucus-retention cysts on the ectocervix, common and harmless
Development
The cervix, body of uterus and upper vagina form from the fused paramesonephric (Müllerian) ducts; failed fusion can give a double cervix, as in uterus didelphys.
Related conditions
- Placenta praevia
- Miscarriage (early pregnancy loss)
- Cervical cancer
- Pelvic inflammatory disease
- Human papillomavirus (HPV) infection
- Trichomoniasis
- Gonorrhoea
- Chlamydia infection
- Syphilis
- Genital herpes (herpes simplex infection)
- Preterm labour and birth
- Premature rupture of membranes (PROM and PPROM)
- Cervical intraepithelial neoplasia (cervical dysplasia)
- Septic and unsafe abortion
- Labour dystocia (arrest of labour, cephalopelvic disproportion)
- Umbilical cord prolapse
- Cervical insufficiency
- Sexual violence (care of the survivor)
- Post-term pregnancy
- Uterine inversion
- Vasa previa
- Müllerian anomalies (MRKH, septate uterus, imperforate hymen)
Test yourself
Think of the answer, then tap the question to see it.
Where does the uterine artery cross the ureter relative to the cervix?
About 2 cm lateral to the cervix at the level of the internal os, the artery passes above the ureter («water under the bridge»), a classic site of injury in hysterectomy.
What does cervical motion tenderness on bimanual examination suggest?
Irritation of the pelvic peritoneum, as in pelvic inflammatory disease or a ruptured ectopic pregnancy.
Which features make up the Bishop score?
Cervical dilation, effacement, consistency and position plus station of the presenting part; a high score means the cervix is favourable for induction.
What does a short cervix on transvaginal ultrasound in the second trimester indicate?
A risk of preterm birth.
In which direction does cervical cancer spread, and what marks advanced disease?
Sideways through the parametrium toward the pelvic side wall; ureteric blockage with hydronephrosis marks advanced disease.
Educational information, not medical advice. For any symptom, see a health professional.
Its names
- Official Latin (TA2)
- cervix uteri; canalis cervicis uteri TA2 3508
- Official Spanish (DeCS)
- Cuello del útero DeCS D002584
- English (TA2)
- Cervix of uterus
- Also called
- cervix uteri
Related
Sources: Terminologia Anatomica (TA2); DeCS; Anatomy, Abdomen and Pelvis: Uterus.
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Representative model, for educational purposes only.
