Therapy areas

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 four 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

Adverse events should be reported. Reporting forms and information can be found at Adverse events should also be reported to Bayer plc.


If you want to report an adverse event or quality complaint, reports can be directed to: Tel: 011820‍63500 or email:


Further information is available on the “contact” tab at