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Vaginal adenosis is the presence of cervical or endometrial tissue inside the vaginal wall that is prone to unusual changes (metaplastic).
The presence of this tissue is understood to be derived from the remnants of the tissue that eventually turns into the fallopian tubes, uterus, and upper vagina, Müllerian ducting.
Vaginal adenosis has generally disappeared from literature, since the recall of an oestrogen drug given to women for a few decades as a miscarriage preventer. It may now occur in adult women without consequence.
Spontaneous (non-DES) vaginal adenosis is relatively common as an incidental finding, reported in around 10 per cent of women, but it is usually silent and harmless.
In women exposed to diethylstilboestrol (DES) in the womb, adenosis is found in about a third overall, rising to as high as 90 per cent in those exposed earliest in pregnancy.
DES exposure does raise the risk of a rare cancer, clear cell adenocarcinoma of the vagina or cervix, by roughly 40 times relative to the background rate.
But the absolute risk stays low, at around 1 in 1,000 DES-exposed daughters, and adenosis itself is benign rather than cancer. This is why DES daughters are advised to have regular specialist monitoring.
How vaginal adenosis occurs in DES-affected women
The exact mechanism of how vaginal adenosis appears is not fully understood, but a working theory exists for DES-affected women. In the womb, the cervix and most of the vagina are lined with a specific cell, columnar epithelium.
At birth, most of these cells have converted to squamous epithelium. Further changes occur at puberty and onwards. DES administration may stop this conversion of cells, and allow columnar epithelium to remain in the vagina and outer portion of the cervix (the ectocervix).1
As the delayed conversion occurs at puberty, these glandular structures are still present. This results in small ‘glands’ in the vaginal mucosa being covered by squamous epithelium, replacing the glandular tissue completely, eventually.
The presence of these glands, either covered or uncovered, is called adenosis. When those benign columnar cells might turn malignant is not well understood, and any cancer typically appears 10 to 30 years after exposure.
The effect seems to be dose-dependent: mothers whose daughters have adenosis or clear-cell cancer had greater exposure earlier in the pregnancy.
How vaginal adenosis occurs in non-DES-affected women
In non-DES women, adenosis is usually spontaneous. The combined pill has been linked to changes (microglandular hyperplasia) developing within existing adenosis, rather than to causing adenosis itself, and any broader hormonal role is speculative.
Frequently asked questions
What is vaginal adenosis?
It is the presence of glandular (columnar) tissue in the vaginal wall, where the lining would normally be smooth, squamous skin. It is usually benign and silent, and is found incidentally in around 10 per cent of women.
Is vaginal adenosis linked to cancer?
Adenosis itself is benign, not cancer. DES exposure in the womb raises the relative risk of a rare cancer (clear cell adenocarcinoma) by around 40 times, but the absolute risk stays low – about 1 in 1,000 DES-exposed daughters – which is why regular specialist monitoring is advised.
What causes vaginal adenosis?
The best-understood cause is exposure to the drug DES in the womb, which disrupts the normal conversion of the vaginal lining before birth. In women without DES exposure, it is usually spontaneous.
This article is general information and not a substitute for personalised medical advice. If you were exposed to DES in the womb or have unusual vaginal symptoms, please see an experienced practitioner.
- Laronda MM, Unno K, Butler LM, Kurita T. The development of cervical and vaginal adenosis as a result of diethylstilbestrol exposure in utero. Differentiation. 2012;84(3):252-60.
