Menstrual Product Absorbency Studies - Scientific American

According to a recent paper published on August 7th in BMJ Sexual & Reproductive Health, researchers have found that many menstrual products have much higher and lower liquid capacity than advertised when real blood was used instead of saline solution. This study was the first of its kind to perform testing with actual blood. The inspiration for this study was derived from the lack of measure/accountability for heavy menstrual flows that can’t be dealt with properly with products on the market right now and often lead to misdiagnoses by health professionals. 

Studies regarding tampon absorbencies in the 1980s were also conducted using saline mixtures, as are most tampon/pad studies today. This is rather problematic because blood and saline solution have very different viscosities, and thus the absorbency metrics that are currently put to use must be updated. 

Blood’s viscosity, as compared to that of water and saline, is highly variable, especially menstrual blood. Menstrual blood contains vaginal secretions that have been shed from the uterine wall. Its viscosity can change from person to person. 

In the new study, led by Samuelson Bannow, discs, tampons, pads, period underwear, and cups were all tested. Period pants had the least absorbency. Light pads were slightly more absorbent, followed by tampons. Menstrual discs had the highest absorbency.

Overall, the results were startling for most members of the scientific community. Interestingly enough, doctors would typically diagnose heavy bleeding based on either a visual chart, called the pictorial blood loss assessment chart, or the frequency with which the individual would need to change their period supply. Prior to these findings, we had probably been inadvertently missing a lot of heavy menstrual bleeding.

Source: https://www.scientificamerican.com/article/no-one-studied-menstrual-product-absorbency-realistically-until-now/