Just saw this being shared on Twitter & Mastodon:  Menstrual Hygiene products for "heavy menstrual bleeding" (HMB).

Apparently, it's the first time they have been using real human blood - instead of water or other fluids - to measure the capacity of these products. Interesting study! 

"Red blood cell capacity of modern menstrual products: considerations for assessing heavy menstrual bleeding"

URL: srh.bmj.com/content/early/2023/07/03/bmjsrh-2023-201895

Abstract
Background
Heavy menstrual bleeding affects up to one third of menstruating individuals and has a negative impact on quality of life. The diagnosis of heavy menstrual bleeding is based primarily on history taking, which is highly dependent on traditional disposable menstrual products such as pads and tampons. Only tampons undergo industry-regulated testing for absorption capacity. As use of alternative menstrual products is increasing, there is a need to understand how the capacity of these products compare to that of standard products.

Methods 
A variety of commercially available menstrual products (tampons, pads, menstrual cups and discs, and period underwear) were tested in the laboratory to determine their maximal capacity to absorb or fill using expired human packed red blood cells. The volume of blood necessary for saturation or filling of the product was recorded.

Results 
Of the 21 individual menstrual hygiene products tested, a menstrual disc (Ziggy, Jiangsu, China) held the most blood of any product (80 mL). The perineal ice-activated cold pack and period underwear held the least (<3 mL each). Of the product categories tested, on average, menstrual discs had the greatest capacity (61 mL) and period underwear held the least (2 mL). Tampons, pads (heavy/ultra), and menstrual cups held similar amounts of blood (approximately 20–50 mL).

Conclusion
This study found considerable variability in red blood cell volume capacity of menstrual products. This emphasises the importance of asking individuals about the type of menstrual products they use and how they use them. Further understanding of capacity of newer menstrual products can help clinicians better quantify menstrual blood loss, identify individuals who may benefit from additional evaluation, and monitor treatment.

and

WHAT IS ALREADY KNOWN ON THIS TOPIC

• Metrics for diagnosing heavy menstrual bleeding (HMB) are dependent on disposable period products (tampons and pads) and have not been modified for use with alternative products such as menstrual cups and underwear.

WHAT THIS STUDY ADDS

• Menstrual cups and discs can hold ≥30 mL of blood. HMB may be underdiagnosed in users of these products. Period underwear is likely to be ineffective for those with HMB. Modern disposable period products also have a high capacity (20–50 mL) and menstrual losses are likely underestimated when using metrics developed with the use of older technology.

HOW THIS STUDY MIGHT AFFECT RESEARCH, PRACTICE OR POLICY

• Clinicians can better assess menstrual blood loss in patients using their preferred menstrual product.

via: mastodon.social/@BethanyBlack/110886684776659288
and mastodon.social/@ErinKernohan/110887002803703731