Almost every woman will experience periods during their life – around 12 periods a year for more than 30 years. But for one in three, this bleeding can be extremely heavy and may require medical help.

Around one in 20 women between the ages of 30 and 49 will seek treatment for heavy menstrual bleeding (HMB) or menstrual problems every year in the UK. Many will be given medication to help manage the bleeding, but this isn’t always effective. Some women may eventually have surgery to help lighten or stop their menstrual bleeding altogether.

It is widely recognised that tightly controlled uterine inflammation, low oxygen levels in the blood (hypoxia) in the uterine lining (endometrium) and efficient and blood clotting are important to prevent HMB.

Now, research funded by Wellbeing of Women, shows MRI scanning can predict oxygen levels in the endometrium, potentially giving doctors a new, non-invasive way to diagnose the underlying cause of heavy periods in some women, facilitating more personalised treatments.

The study was led by Dr Jacqueline Maybin, Reader and Honorary Consultant Gynaecologist at the Centre for Reproductive Health at the University of Edinburgh.

Dr Maybin’s research suggest that the blood vessels found in the endometrium need to narrow at menstruation to minimise blood loss during a period and create the tissue hypoxia that is required to drive the normal repair process following shedding at menstruation.

This opens the door to future treatments that target the endometrial blood vessels to limit menstrual bleeding, enabling those with HMB to access more specific medical care and avoid fertility removing surgery.

What is heavy menstrual bleeding?

HMB may be caused by an imbalance of three main factors within the uterus: inflammation of the womb lining, hypoxia and blood clotting. These are called ‘non-structural’ causes.

For other women, heavy periods may be caused by other conditions, such as endometriosis, adenomyosis or fibroids. These are ‘structural’ causes and will require a referral to a gynaecologist for further help and treatment.

Diagnosing HMB can take time because it can be difficult for women to distinguish if their menstrual bleeding is heavy or not due to the taboos surrounding periods and a lack of awareness. In addition, diagnosing non-structural causes can be difficult with the routine investigations that are currently available. This means those experiencing HMB may suffer for years before finding a suitable treatment.

Assessing oxygen levels in the blood during menstruation

Dr Maybin and her research team studied endometrial samples collected from 16 women during a period and when not menstruating, measuring markers of hypoxia. All of the women had normal menstrual bleeding and none were taking hormonal contraceptives or had any known gynaecological conditions.

In addition to the endometrial samples, women consented to have magnetic resonance imaging (MRI) of their uterus at both phases of their menstrual cycle to assess the amount of blood flowing through the endometrial blood vessels and measure an indicator of low oxygen levels in the tissue.

Dr Maybin and her team discovered that women had signs of hypoxia during a period but not at other times of the menstrual cycle, both in laboratory tests of their endometrial tissue and detected non-invasively by MRI.

This is the first time hypoxia has been detected directly in the endometrium of women. It shows that MRI scans can help detect endometrial hypoxia non-invasively, and potentially be used to detect a lack of hypoxia that is linked with HMB.

Dr Maybin says:

“Heavy menstrual bleeding is common among women and can have a major impact on a woman’s quality of life. It is often extremely debilitating and can make women anaemic, resulting in fatigue and shortness of breath. HMB also affects their mental wellbeing and has a negative financial impact due to sick leave and a loss of earnings.

Next steps

Dr Maybin hopes these findings will lead to MRI scanning being researched as a potential method to detect if a lack of hypoxia is present in endometrial tissue in those with HMB. She hopes this will lead to faster diagnosis and more tailored management for those living with this debilitating symptom.

Wellbeing of Women is funding a number of research projects to understand more about heavy menstrual bleeding, including a study looking to understand if menstrual fluid can be a reliable method to identify heavy periods and possible causes like adenomyosis and fibroids.