By Iván Ferrer Durbà BSc (biologist & science teacher).
Last Update: 02/20/2015

Generally, clots appear during the menstruation due to an excessive blood flow. These clots form when the agents that act as anticoagulants in the body cannot maintain the fluidity of the blood.

It is important to keep in mind that, the period is the expulsion of the endometrium, that is to say, the mucous membrane that lines the uterus. It occurs when the woman is not pregnant.

Coagulation during menstruation

The mucous protects and nourishes the embryo and, if there’s no fertilization and it doesn’t have to fulfil its function, the mucous detaches from the uterus and exists the female body followed by blood.

Menstrual clots: causes

Normally, the woman is not able to identify this tissue because its is gradually expelled, although, sometimes, all the mucous that covers the uterus can be released at the same time. This is a tissue that does not fall apart when touched and, its complete expulsion at once is not frequent.

The total shedding of the endometrium, a rare occurrence should not be confused with the expulsion of clots, which is normal.

Clots can either be small or large and, usually, appear when menstrual bleeding is very heavy and dense. Sometimes, these clots can be dark and cause some pain.

Blood has a clotting factor and for the menstrual blood to be able to flow freely from the uterus it has to produce a anticoagulant called plasmin . This agent is in charge of analyzing and controlling another protein called fibrin, which fuses with other molecules and forms soft clots. When menstrual bleeding is abundant, plasmin might not be enough and some blood clots may form.

Clots during menstruation

If the woman doesn’t suffer from any pathology like anaemia or endometriosis, there’s no reason to worry. However, if the menstruation is too painful, the woman should visit a gynaecologist in order to rule out any possible pathology.

Sharing is caring

Our editors have made great efforts to create this content for you. By sharing this post, you are helping us to keep ourselves motivated to work even harder.

Authors and contributors

 Iván Ferrer Durbà
BSc
Biologist & Science Teacher
Bachelor's Degree in Biology by the University of Valencia (UV). Postgraduate Course in Secondary Education and Teaching by the University of Portsmouth. Teacher of Sciences at multiple British schools and high schools. More information
Follow us on social media

Find the latest news on assisted reproduction in our channels.