No, it will not. The opening of the uterus (cervical opening) only allows for the exit of products (and babies) and entry of sperm (which actually swim upwards into it). If instruments need to be introduced into the uterus (for diagnostic or treatment purposes), firm instruments are usually used in order to gain access into the uterine cavity. Right after the instruments are taken out or the baby and afterbirth are taken out, the cervical opening closes up. This means that your flow cannot return into the uterus.

Menstrual flow is also not entirely watery, it is thick and viscous and sometimes contains clots. Also note that when on your period, the uterus constantly pushes blood out through its opening.

What happens when my cup is filled up?

When your cup fills up, the blood flows downwards into your vagina (starts to leak) rather than upwards into your uterus. Gravity also only allows your menstrual blood to flow downwards.

Several articles have been in circulation that insinuate that menstrual cups lead to endometriosis by way of causing a backflow of blood into the uterus.

This is far from the truth as the cervical opening cannot admit even the tiniest amount of non-viscous fluid (for example water). There also have not been enough clinical studies to prove the theory.

If you are still in doubt or concerned about backflow of blood or endometriosis, feel free to contact us. One of our knowledgeable and experienced representatives will be on the other end of the line to respond to your questions. We always look forward to receiving questions, comments and feedback from our clients. In the meantime, you can ensure that you empty your cups as often as you can, just so blood doesn’t get to sit in your vagina for hours. You could also speak with your gynecologist about your reservations of using a cup.