Scientists found that many goods’ stated sizes were not accurate, and that menstrual cups and discs could hold the most blood. Their findings raise important questions about how doctors identify heavy monthly blood.

Even though blood is stronger than water, salt has always been used to figure out how much liquid a menstrual product can hold.

A common way to figure out how much blood is lost is to look at how much standard bleeding products can soak up. Clinicians use it to figure out what’s causing heavy monthly bleeding, which affects about a third of women around the world (18.2% in China and 37.9% in Turkey) and could be a sign of more serious problems like fibroids.

But evaluation is hard when people use unusual tools like discs and cups, or when the stated abilities of the tools aren’t accurate.

“No records with blood.”

Now, researchers from Oregon Health & Science University (OHSU) have released a study in the journal BMJ Sexual & Reproductive Health on August 7 about how well standard and novel period products take human blood instead of water or other fluids.

They found that many product claims about how much they could hold were not accurate.

A group of doctors said that it was important to test menstrual goods with blood because “blood, not urine, has to be absorbed.” (Salt water is like pee.)

Bethany Samuelson Bannow, an assistant professor of medicine at OHSU and one of the authors of the study, said that the fact that more of their patients are using menstrual cups made her team want to test the absorbency of unusual items as well. “We decided to find out how much alternative period products soak up,” Dr. Bannow wrote in an email to this writer. “As we looked at how disposable products are tested, we realized that there is no information on how much blood these products can absorb.”

From underwear to record discs

Her team tested the ability of 21 everyday items, like discs, cups, tampons, sanitary pads, and underwear, with packed red blood cells (RBCs) taken from whole blood. The names they picked can be bought in stores in the U.S. and Europe, and some of them can also be bought online in Asia.

For their tests, the team chose pads and tampons from two different brands with different reported absorbencies, as well as three pairs of period underwear from the same brand with the same reported absorption. They also tried different sizes of menstrual cups from the same brand and two sizes of discs from different brands.

To test how well pads and period undies could soak up blood, the team poured RBCs over the middle third until the RBCs gathered below or the product stopped soaking them up.

Researchers put each tampon in a cup with 50 ml of RBCs for 30 minutes, or until the blood hit the wick, to see how much blood it could hold. They then wrote down how much blood each tampon had received. They also put RBCs to the top of cups and plates and measured how much space they took up.

They found that menstrual underwear, no matter what size, soaked up the least amount of blood, on average only 2 ml. This surprised Dr. Bannow. Menstrual plates held the most: an average of 61 ml, and one brand could hold up to 80 ml. Tampons, pads, and menstrual cups held between 20 and 50 ml.

How does heavy bleeding happen?

The most important thing Dr. Bannow learned was that menstrual cups and discs can hold a lot of blood. So women who use these items more than once during their cycle are likely to have heavy periods.

“In the end, we want every woman who menstruates to know if her periods are really “normal” and to be able to get checked out and treated if they are heavy.”

The measures the researchers took also didn’t match what the ads said.

Researchers have written in the journal BMJ Sexual & Reproductive Health about how well standard and nontraditional period products take not saline fluids but human blood.

“We weren’t too surprised that pads and tampons absorbed more blood than saline,” said Dr. Bannow, adding that this had been said before but not written down. Even though a product that soaks up more blood might seem like a good thing, it could be hiding heavy bleeding.

According to Dr. Kamath, it is crucial to differentiate between normal and severe menstrual flow due to the potential health complications associated with heavy bleeding.

An independent doctor named Ananya Petkar said, “Blood and water have very different viscosities and make-ups, so we can’t expect a product to hold both of them the same way.” “This study is a great way to find out how well different products can absorb.”

In their study, the writers, including Dr. Bannow, admitted that even though RBCs are thicker than water, they are still not a perfect substitute for menstrual blood, which also contains uterine cells and vaginal liquids. The consistency of menstrual blood also varies from person to person and day to day.

Dr. Bannow and his team are now looking at how menstrual cups and period underwear help women who have heavy periods.

Not enough research

Dr. Petkar also said that the experts filled each product with blood to figure out how much blood it could hold. But in real life, women might not wait until a pad or cup is fully full before changing it. This also makes it hard to compare the results of the study to how the goods are actually used and what their health effects are.

Both Dr. Kamath and Dr. Petkar say that another problem with using this study in Asia is that not all of the goods studied are as easy to find there as they are elsewhere. Dr. Kamath said that cups and discs aren’t used as much in Asia because it takes “practice and a little bit of knowledge of the female anatomy” to use them.

“We can only teach other people about heavy menstrual bleeding and treat it if we know the right way to measure blood loss,” Dr. Kamath said. “To do that, we need to learn more about this subject.”

There is still not much known about menstruation. In the PubMed database, “menstrual blood” was mentioned in 400 papers between 2011 and 2018, but semen was mentioned in more than 10,000 papers.

Dr. Bannow said, “I think people in general need to feel more at ease talking about periods.” She was happy that her latest work is getting so much notice. It “brings up to the forefront a discussion about menstruation.”