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Cervicitis, ectropion and pseudoerosion

How the two linings of the cervix meet and move, why hormones bring columnar lining out as an ectropion (the old "erosion", really a pseudoerosion), how Nabothian cysts and polyps form, and how sexually transmitted organisms inflame the cervix.

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  • 5 steps · 10 questions
  • 3D normal anatomy

By the end, you can

  • Describe the ectocervix, endocervix, squamocolumnar junction and transformation zone, and explain how squamous metaplasia forms the zone.
  • Explain how oestrogen at puberty, in pregnancy and with combined hormonal contraception brings columnar epithelium onto the ectocervix, and distinguish ectropion (pseudoerosion) from a true erosion in current terms.
  • Explain how Nabothian cysts and endocervical polyps form and why both are benign.
  • Explain how Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis and herpes simplex virus inflame the cervix, and describe chronic non-specific cervicitis.
  • Relate contact bleeding, discharge and the look of the cervix to their causes, recognise the tissue picture, tests and differentials, and explain how the main treatments act on the mechanism.

What it is

Cervicitis is inflammation of the cervix. Acute cervicitis is usually a sexually transmitted infection, most often of the endocervix; chronic non-specific cervicitis is common, low-grade inflammation, often without a cause. Ectropion (ectopy) is columnar epithelium of the endocervix lying on the vaginal surface of the cervix, a normal change driven by oestrogen. It looks red and raw, so it was once called an erosion; because its surface is intact it is a pseudoerosion, and ectropion is the current term. A true erosion is a real loss of epithelium.

5 types to tell apart
Ectropion (ectopy; formerly "erosion")
Columnar epithelium on the ectocervix under oestrogen: in newborns, adolescents, pregnancy and with combined hormonal contraception. A normal variant; it can cause more mucus and bleeding after sex.
True erosion
An area where the epithelium has been lost, exposing the stroma: injury from instruments or a pessary, thin atrophic epithelium after the menopause, herpes ulcers or a tumour.
Nabothian cysts and endocervical polyps
Benign: mucus trapped in crypts covered by squamous metaplasia, and a focal overgrowth of endocervical mucosa, often inflamed, on a stalk.
Acute (infective) cervicitis
Mainly Chlamydia trachomatis, then Neisseria gonorrhoeae, in the columnar endocervix; Trichomonas vaginalis and herpes simplex virus also inflame the squamous ectocervix. Mycoplasma genitalium is a less common cause.
Chronic non-specific cervicitis
Lymphocytes and plasma cells in the stroma of the transformation zone: very common, often found by chance, from persisting abnormal flora, irritants, foreign bodies or no clear cause.

US spelling: oestrogen → estrogen, tumours → tumors.

Normal function

Two linings and the junction between them

The is the narrow lower part of the uterus; its lower half projects into the , ringed by the vaginal fornices, deepest behind (). Its stroma is dense collagen with little muscle. The ectocervix, facing the vagina, is covered by non-keratinising stratified squamous epithelium many cells thick, pale pink and, under oestrogen, rich in glycogen. The canal, or endocervix, runs from the to the and is lined by a single layer of tall, mucus-secreting columnar cells, which also line branching clefts in the stroma (crypts, usually called glands).

Endocervical mucus changes with the cycle. Around ovulation, oestrogen makes it thin, clear and stretchy, so sperm can pass; under progesterone it becomes a thick, sticky plug that holds back sperm and bacteria. It carries antibodies and antimicrobial peptides. Below it, lactobacilli keep the vagina acidic.

The line where the two linings meet, the squamocolumnar junction, is not fixed: it lies out on the ectocervix when oestrogen is high and retreats into the canal after the menopause. Columnar epithelium left in the acidic vagina is gradually replaced by squamous epithelium (squamous metaplasia). The band of metaplastic epithelium between the original junction and the current one is the transformation zone, where cervical screening samples are taken and most cervical tumours begin.

Point to it on the model