Question & Answer

Can a menstrual cup dislodge an intrauterine device (IUD)?

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The Evidence

Menstrual cups are an alternative to tampons and sanitary towels. The cup is made from silicone and is placed inside the vagina during a woman’s period. The cup collects blood and can be washed and used again.
An intrauterine device is a form of contraception where a device is placed inside the womb. There have been claims that people who have an intrauterine device (IUD) fitted and who use menstrual cups are more likely to experience dislodgement of the IUD from the body, compared to those who use sanitary towels or tampons.
We looked for studies to see if using a menstrual cup was associated with IUDs being dislodged, and we found two systematic reviews.
One of these looked at a review of hospital charts, an internet survey and some case series and case reports of women whose IUDs had dislodged while using a menstrual cup.
- The review of 743 hospital charts didn’t find any difference in rates of IUD dislodgement between menstrual cup, sanitary towel or tampon users.
- The internet survey found an increased risk of IUD dislodgement and use of a menstrual cup. However, women who have had a problem with menstrual cups are more likely to volunteer to take part in a survey like this. Therefore, the survey is more prone to bias because it isn’t representative of all women using menstrual cups, and we can’t depend on its findings.
- It is not advisable to rely solely on case reports or case series as evidence for a particular health care treatment or other intervention, because they only consider people who have experienced a certain problem, and do not account for those who have not. Therefore, such information is not as helpful in finding out if the expulsion of IUDs was due to menstrual cups or it would have happened anyway.
The second systematic review included the studies mentioned above and didn’t provide any further information.
We would need some well-designed randomised studies to figure out whether menstrual cups are more likely to lead to dislodgement of IUDs compared to, say, sanitary towels or tampons.
Dislodgement of IUDs is rare, which means we would need studies with large numbers of women in them to even see a few dislodgements. As a result very large studies would be needed in order for us to say with confidence whether there really is a difference between women who use a menstrual cup and those who don’t.

Guidelines and recommendations

We did not find any guidelines or recommendations on the topic.

Things to Remember

Just because something is associated with getting worse (or better) doesn’t mean it caused it. It may have happened by chance or because of something else.
Look out for claims based on studies that include few people or events. We cannot be sure of results from these kinds of studies.

Reviewers

Lead Researcher: Dr. Paula Byrne, Senior post-doctoral researcher, iHealthFacts, Evidence Synthesis Ireland and Cochrane Ireland, College of Medicine, Nursing and Health Sciences, University of Galway.
Reviewed by: Prof Declan Devane, Professor of Health Research Methodology, Deputy Dean, College of Medicine, Nursing and Health Sciences, University of Galway,
Scientific Director, HRB-Trials Methodology Research Network Director, Evidence Synthesis Ireland. Director, Cochrane Ireland
Topic advisor: Prof. Susan M Smith, Professor of General Practice, Discipline of Public Health and Primary Care, Trinity College Dublin and General Practitioner in Inchicore Family Doctors, Dublin 8.
Public and Patient advisor: Deirdre Mac Loughlin, Public and Patient Involvement in research (PPI) advisor, PPI Ignite, University of Galway.
Journalist Advisor: Dr. Claire O’Connell, PhD in cell biology, Masters in Science Communication. Contributor to The Irish Times, writing about health, science and innovation.

Conflict of Interest Statement: The authors have no financial or other conflicts of interest for this health claim summary.

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