The Endometrium
The endometrium is the inner lining of the uterus (womb). Each month, under the influence of hormones, this lining thickens in response to normal reproductive hormone changes. If fertilisation does not occur, the lining is shed during a period as part of the menstrual cycle. Endometrial hyperplasia occurs when this lining becomes thicker than normal. The cells in the endometrium grow and multiply too quickly, usually because there is too much oestrogen and not enough progesterone to balance it. After the menopause, hormone levels fall and the endometrium normally becomes thin and inactive, but hormonal imbalances can still sometimes cause it to thicken abnormally.
Understanding Endometrial Hyperplasia
The hormonal imbalance driving endometrial hyperplasia can develop for a variety of reasons, for example, during perimenopause or after menopause, when ovulation (and therefore progesterone production) becomes irregular or stops. In most cases, endometrial hyperplasia is not cancer, but certain types can increase the risk of developing endometrial cancer over time if left untreated. That’s why early assessment and monitoring are important. The main symptom of endometrial hyperplasia is abnormal vaginal bleeding. This can vary depending on whether you are still having periods or have gone through menopause. You may notice:
- Heavy or prolonged periods
- Bleeding between periods
- Short menstrual cycles (bleeding more often than usual)
- Bleeding after sex
- Any vaginal bleeding after menopause
Post-menopausal bleeding, even a small amount, should always be checked by a healthcare professional.
Types of Endometrial Hyperplasia
Endometrial hyperplasia without atypia
This is the most common and mildest form. The cells of the womb lining are normal, but there are more of them than usual. The risk of this type developing into cancer is very low, especially with proper treatment or monitoring.
Endometrial hyperplasia with atypia
Also called atypical hyperplasia. In this type, the cells not only increase in number but also appear abnormal. This form carries a higher risk of turning into endometrial (womb) cancer if left untreated, so closer follow-up and more active treatment are often recommended.
What causes Endometrial Hyperplasia?
Endometrial hyperplasia develops when the lining of the womb (endometrium) is exposed to too much oestrogen without enough progesterone to balance it. This hormone imbalance causes the lining to keep thickening instead of shedding normally. You may be more at risk if you:
- Age & menopause status More common in people over 40 or post-menopausal, when hormone patterns change.
- Irregular ovulation PCOS or infrequent periods reduce progesterone, allowing the lining to thicken.
- Weight Overweight or obesity increases oestrogen production from body fat.
- Hormone therapy Oestrogen-only HRT without progesterone raises risk.
- Health conditions Type 2 diabetes or high blood pressure are associated with higher risk.
- Reproductive history Risk is slightly higher in those who have never been pregnant.
Diagnosing Endometrial Hyperplasia
If your doctor suspects endometrial hyperplasia, often due to abnormal or post-menopausal bleeding, they’ll arrange tests to check the thickness and appearance of the womb lining. Common tests include:
- Ultrasound A transvaginal ultrasound uses sound waves to show how thick the lining of your uterus is. A thickened endometrium can suggest hyperplasia.
- Hysteroscopy In some cases, a thin camera is passed through the cervix into the uterus to look directly at the lining and guide targeted biopsies.
- Endometrial Biopsy A small sample of tissue is taken from the womb lining and examined under a microscope to confirm the diagnosis and determine the type (with or without atypia).
Treatment Options
Treatment depends on the type of endometrial hyperplasia, your age, whether you are still having periods, and whether you want to preserve fertility.
Medical Treatment
- Progesterone therapy Often given as tablets, injections, or a hormonal IUD, this helps balance oestrogen and reduce the thickness of the womb lining.
- Regular monitoring Follow-up ultrasounds and biopsies may be used to make sure the lining returns to normal.
Surgical Options
- Hysterectomy Complete removal of the uterus is usually reserved for women with atypical hyperplasia who do not wish to maintain fertility or when medical treatment is not suitable.
- Hysteroscopic resection or polypectomy In some cases, localized thickened areas or polyps can be removed using a camera and small instruments inserted through the cervix.
Treatment is tailored to your needs, and your doctor will discuss the most appropriate options for your situation.