This article is written by medical professional Dr. Alice Byram, whom you can read more about at the end of the article.

Although many people will have heard about the cervix, it’s exact location and functions understandably can remain a mystery. If you are going to use a menstrual cup, and there are many good reasons to do so, then you need to know a little about your cervix.

Becoming familiar with your cervix is helpful for self-knowledge, choosing the right size menstrual cup for your body and using a menstrual cup. It is also the area from which a sample will be taken during a pap smear or smear test which should be done every 2 - 3 years.

Where and what is the cervix?

Imagine the cervix as the “neck of the uterus”. It’s the part that connects the vaginal canal with the uterus. It can vary in length, usually between 3-4 cm long(1). If you have a longer cervix, your vaginal canal will be shorter. And if you have a high cervix your vaginal canal will be longer.

What does the cervix look like?

You can imagine the cervix looking like a small doughnut. It is about 2-3 cm in diameter and with a tiny hole in the middle (hence the doughnut reference), where your menstrual blood will flow out and sperm will go in.

Depending on the phase of your menstrual cycle, your cervix will look different, and even shift position due to hormonal fluctuations. It opens up completely during childbirth to let the baby through.

What is the function of the cervix?

The cervix is the connection between the outside world and your inner reproductive organs. It is a barrier which opens to let your menstrual blood out during your period. It also opens and closes to let sperm in during and just after sexual intercourse. Should you become pregnant your cervix will create a mucus plug which acts as an extra level of defence against germs from the outside, whether virus or bacteria.

What does your cervix have to do with your menstrual cup?

If you know the length of your cervix, you’ll know if you have a shorter or a longer vaginal canal. This will give you an idea as to which period cup size you should choose to ensure that it will fit snugly and comfortably inside your vagina.

The Ruby Cup, for instance, comes in two sizes, small and medium. As you read above, the length of the cervix can vary. That means that if you have a low cervix, your vaginal canal is shorter, and if you have a high cervix, your vaginal canal is longer.

How to measure the height of your cervix

Here’s a step-by-step feel-guide to working how the height of your cervix and therefore the right size menstrual cup for you:

1. Wash your hands thoroughly including underneath your fingernails. If you have any nail extensions, consider doing this at a time when you don’t have any as you may cause damage to the cervix wall.

2. Squat or put one leg on the toilet. You can also do this in the shower as if you were about to apply a tampon (for those not using a menstrual cup yet)

3. Insert your longest finger into your vagina, or whichever one feels most comfortable, and notice how far in it goes. You will feel a soft roof past which you can not push. If you are not sure if it is the cervix “roof” or the vaginal wall, you can try to feel a dip or opening.

4. Use how far your knuckles go in to work out your cervix height.

This measurement method is an orientation, as finger lengths vary widely, but it will definitely give you a closer idea of where your cervix sits.

1. Best Menstrual Cup for a High Cervix

If you can insert your longest finger almost all the way up, you have a high cervix.

What to look out for in a menstrual cup if you have a high cervix (long vaginal canal):
If you have a high cervix then you will need a longer menstrual cup so that it is easy to reach and remove. A small cup can travel up the cervix making it hard to reach. The Ruby Cup Medium is a great fit for a high cervix.

2. Best Menstrual Cup for an Average Cervix

If you can insert your longest finger until the middle knuckle, then you have an average cervix. If you have an average cervix then you can use a Ruby Cup Medium or Ruby Cup Small. Use a medium if you have a heavy flow or small for a lighter flow. Tip: many people have both sizes and choose the cup according to where in their cycle they are. You can also trim the stem of your menstrual cup to make sure it fits comfortably in your vagina.

3. Best Menstrual Cup for a Low Cervix

If you can insert your longest finger only until slightly above the middle knuckle, then you have a low cervix.

Look for a short menstrual cup that fits comfortably inside your vagina. This helps avoid the stem poking out, which can feel uncomfortable against your labia. Choose a Ruby Cup Small or cut the stem off your Ruby Cup Medium.

4. Try a menstrual cup to know for sure - our money-back guarantee has your back.

All Ruby Cups are covered by our 100% money-back guarantee. Switch size or get a full refund within 120 days of purchase. No questions asked.

Let us know if this comprehensive guide helped you understand which menstrual cup is best for you based on your cervix. If you still have doubts, you can always reach out to us via email. Our menstrual cup coach will take time to answer your questions.

Looking for a high-impact, beginner-friendly menstrual cup? Ruby Cup is the #1 choice for first-time menstrual cup users and the world’s leading menstrual cup donor. For every cup you buy, we give one to someone without access to safe menstrual products. Get your Ruby Cup now. 

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Written by Dr Alice Byram Bsc Med & Surg UMA MA Hons MML Cantab

Dr Alice Byram was born in England to a French-British family. Following on from a degree in Spanish from the University of Cambridge, she went to Spain to study medicine. On her return to the UK, she worked in Emergency Medicine for several years before recently returning to Barcelona.

Date last reviewed: February 2020

References: 

1. Levine DA, Dizon DS, Yashar CM, Barakat RR, Berchuch A, Markman M, Randall ME. (2015). Handbook for Principles and Practice of Gynecologic Oncology. (2nd Edition). Philadelphia, PA: Wolters Kluwer.