The hormonal changes that occur at menopause cause a woman’s menstrual periods to stop and result in the end of her reproductive years. The disrupted balance between oestrogen and progesterone can also lead to other conditions, including endometrial hyperplasia.
Although endometrial hyperplasia can occur in women who are in perimenopause, it is most common among women in their 50s and 60s who have gone through menopause1. That being said, it is a rare condition, affecting around 133 out of 100,000 women2.
However, it is important to be aware of the symptoms and risk factors of endometrial hyperplasia as it is a precancerous condition that if left untreated, can develop into endometrial cancer.
What is endometrial hyperplasia?
The endometrium is the lining of the uterus. It is what is shed during a menstrual period and is also the tissue that an embryo implants into during pregnancy. Endometrial hyperplasia is when the endometrium becomes too thick because the cells are growing more than expected3,4.
Types of endometrial hyperplasia
Endometrial hyperplasia is categorised based on the kind of cell changes in the endometrium. There are two types: Endometrial hyperplasia without atypia, and atypical endometrial hyperplasia.
- Endometrial hyperplasia without atypia is where more cells have been produced within the womb lining which crowd together, making the lining look thicker. However the cells themselves look normal in structure.
- Atypical endometrial hyperplasia is where the cells look abnormal and are described as atypical looking cells. This type of hyperplasia has a higher risk of developing into endometrial cancer.
Endometrial hyperplasia without atypia
This type of endometrial hyperplasia indicates that there are some early changes to the cells of the endometrium. If left untreated, this type has up to a 5% risk of progression to cancer over 20 years4.
In many women with this type of endometrial hyperplasia, the womb lining may return to normal without treatment if there are other modifiable risk factors. However the success rate of a watch and wait option is lower (76%) compared to having progesterone based treatment (89-96%).
Atypical hyperplasia
Atypical hyperplasia) presents a more significant risk of cancer. In addition there is a 25-40% risk of there already being cancer present in a part of the womb that has not been biopsied; this may only show following a hysterectomy4.
What causes endometrial hyperplasia?
A thick lining of the uterus after menopause is caused by an imbalance of oestrogen and progesterone in the body.
This can occur as a result of:
- Increased body weight
- A history of irregular or absent menstrual periods e.g. PCOS
- Hormonal imbalances e.g. oestrogen secreting tumours
- Medications e.g tamoxifen
- Use of oestrogen only HRT when a woman still has a uterus present
- Long-term use of high doses of oestrogen HRT without sufficient progesterone2
Within a normal menstrual cycle, oestrogen thickens the endometrium, while progesterone counteracts this growth and prepares the uterus for pregnancy. If pregnancy doesn’t occur, progesterone levels drop which triggers the endometrium to shed, resulting in a period. With little or no progesterone in a cycle, the endometrium cannot shed and the oestrogen would be unbalanced.
A thick lining of the uterus after menopause arises because there isn’t enough progesterone to counteract the effects of oestrogen (even though levels are lower than before menopause). The endometrium continues to grow but as menstrual periods have stopped, it doesn’t leave the body.
Hormone replacement therapy (HRT), which replenishes oestrogen and progesterone can slightly increase the risk of certain conditions. For example, there is a link between HRT and breast cancer. HRT use also has a small increased risk of endometrial hyperplasia and uterine cancer which is lessened when using appropriate progesterone alongside oestrogen.
Studies suggest that approximately 20% of women using oestrogen-only HRT for one year, who have a uterus still present, develop endometrial hyperplasia, with the risk rising to 62% after three years of unopposed oestrogen use.
During perimenopause when a woman is still having periods, the recommended progesterone duration is 12-14 consecutive nights per month; this is called sequential combined HRT. Women taking sequential combined HRT with less than 10 days of progesterone each month are also at increased risk. The prevalence of endometrial hyperplasia in these circumstances is 5.4%6,7.
The progesterone dose must also be proportionate to the oestrogen in the HRT regime.
Risk factors for endometrial hyperplasia
Any woman can develop endometrial hyperplasia. However, there are risk factors that increase the chance of it occurring. These include:
- Obesity
- Diabetes
- Gallbladder disease
- Polycystic ovary syndrome (PCOS)
- Smoking
- Thyroid disease
- Having never been pregnant
- Taking tamoxifen for breast cancer
- Lynch syndrome
- Cowden syndrome
- Starting menstrual periods at an earlier age
- Menopause at a later age
- A compromised immune system
- A personal or family history of uterine, ovarian or colorectal cancer 1,2,8
Symptoms of endometrial hyperplasia
The main symptom of endometrial hyperplasia is changes to menstrual bleeding or unexpected vaginal bleeding.
Symptoms of endometrial hyperplasia may include:
- Bleeding between periods
- Heavy, longer lasting periods
- Vaginal bleeding after menopause
- Increased amount of brown vaginal discharge
- Bleeding or spotting after sex
How is endometrial hyperplasia diagnosed?
As many conditions can cause abnormal vaginal bleeding, diagnosing endometrial hyperplasia usually takes a multi-step approach of reviewing a woman’s medical history and symptoms, physical examination and diagnostic tests.
Transvaginal ultrasound
A transvaginal ultrasound is a common imaging procedure. It involves a probe being inserted into the lower part of the vagina which captures images of the pelvic cavity, including the uterus. These images can show if the endometrium is too thick1, and look for other causes of bleeding such as polyps or ovarian cysts
Endometrial biopsy
If the lining of the uterus does appear too thick, a biopsy is carried out to confirm if hyperplasia is present. This is done by using a small flexible plastic tube inserted into the womb through the cervix. A small amount of endometrial tissue is removed so that it can be looked at under a microscope to assess if hyperplasia is present.
Hysteroscopy
Alternatively, a hysteroscopy may be offered instead. In this procedure, a thin tube called a hysteroscope, which has a camera and a light, is inserted into the vagina and through the cervix into the uterus. This allows the inside of the uterus to be visualised. A biopsy can be done at the same time.
How is endometrial hyperplasia treated?
Treatment of endometrial thickness after menopause depends on the type of endometrial hyperplasia and medical history.
In most instances of thickening of the uterus after menopause, a progestogen-based treatment is used to reverse the changes to the uterine lining. This may be:
- Continuous oral progesterone such as medroxyprogesterone acetate or norethisterone.
- An intrauterine device (IUD) that gradually releases progesterone (Mirena Coil)11.
For women who have atypical endometrial hyperplasia with abnormal looking cells, a hysterectomy may be recommended. This may also be suggested following progesterone treatment should it not be successful in reversing womb lining thickening
Outlook for endometrial hyperplasia
Most people with endometrial wall thickening after menopause respond well to progesterone treatment. Studies have shown regression of hyperplasia without atypia to normal endometrial thickness levels in 80 to 90% of patients when treated with either medroxyprogesterone acetate, or a hormone intrauterine device (Mirena Coil).
The risk of it developing into cancer depends on the type of endometrial hyperplasia you have.
How to prevent endometrial hyperplasia
While anyone can develop endometrial hyperplasia, some steps can be taken to reduce the risk:
- Using a combined HRT regimen which includes a proportionate progesterone if you still have a uterus
- Maintaining a healthy weight
- Quitting smoking
- Getting prompt medical advice about any unusual bleeding if you take tamoxifen for breast cancer.
At Menopause Care, our team are here to help you navigate every stage of menopause and look after your physical and mental well-being. We are knowledgeable about how menopause and other conditions are linked and can support you with evidence-based resources, tailored guidance and a personalised treatment plan. If you want to speak to an experienced specialist about your symptoms, book a consultation with a menopause doctor.
²Endometrial Hyperplasia: Causes, Symptoms & Treatment (February 2023)
³Endometrial Hyperplasia | ACOG (February 2024)
⁴⁵Types of endometrial hyperplasia (February 2019)
⁷Progestogens and endometrial protection (October 2021)
⁹¹⁰Role of Progesterone in Endometrial Cancer - PMC (January 2010)
¹¹Management of Endometrial Hyperplasia (February 2016)
