Endometrial hyperplasia

What is endometrial hyperplasia?

Endometrial hyperplasia is broadly defined as an excessive cellular proliferation leading to an increased volume of endometrial tissue. It is characterised by an increase in the endometrial gland-to-stroma ratio greater than 1:1.1


Endometrial hyperplasia is further classified as simple or complex, with or without atypia. This classification system is based on the complexity and crowding of the glandular architecture.1

The most common presenting symptom of endometrial hyperplasia is abnormal uterine bleeding, including:


However, endometrial hyperplasia can also be asymptomatic and can spontaneously regress without being detected.1

Histological classification of endometrial hyperplasia

Aetiology and risk factors

Oestrogen stimulates endometrial proliferation.1 A relative excess of oestrogen (exogenous or endogenous) compared with progesterone is considered to be one of the principle causes in endometrial hyperplasias.1


Key risk factors in post-menopausal women include:


  • Unopposed oestrogen1,2
  • Obesity, particularly in nulliparous women1,2


Other risk factors include:


  • Diabetes1,3
  • Hypertension1
  • Polycystic ovary syndrome2,3

Incidence and diagnosis

Transvaginal ultrasound

There are approximately


new cases of endometrial hyperplasia in the UK each year.1

Transvaginal ultrasound

The only levonorgestrel intrauterine system licensed for five years for endometrial protection during oestrogen replacement therapy (ERT)1


Efficacy and safety

The efficacy of Mirena® in preventing oestrogen-induced hyperplasia in peri-menopausal and postmenopausal women has been assessed in various studies.2,3



No hyperplasia was detected in any of the trials, regardless of dose, method of administration of oestrogen component or duration of therapy.2,3,4



Mirena® significantly decreased menstrual bleeding compared with conventional oral hormone replacement therapy (P=0.001, N=200).2



Continuing Mirena® use during the transition from contraception to ERT has no adverse effects on the vaginal bleeding profile.5

proportion of patients


The proportion of patients who had difficulties in coping with any items from the Women's Health Questionnaire decreased during both the contraception and ERT phases with Mirena®.5

Find more Mirena® Product Information here.

Reporting adverse events and quality complaints

If you want to report a side effect or quality complaint, please contact your health care professional (e.g. physician or pharmacist) or The Health Products Regulatory Authority, Reports can also be reported directly to Bayer through this link or by emailing directly on adr-reland@bayerhealthcare.com