Introduction

For decades, visual guides like colored droplets and terms such as "heavy" or "light" on menstrual product packaging have been primary references for users. A landmark study published in August 2023, however, reveals a significant discrepancy between labeled absorbency and actual performance, attributed to the industry's standard testing method using saline solution instead of human blood. This research represents the first systematic measurement of various menstrual product absorption rates using real human blood, raising critical questions for women's health, particularly regarding the diagnostic standards for Heavy Menstrual Bleeding (HMB).

Methodology: A Shift to Real Blood Testing

Driven by clinical observations of patients using reusable products like menstrual cups, a research team led by clinician and hematology professor Dr. Bethany Samuelson Bannow conducted this study. The aim was to address the inadequacy of existing HMB diagnostic criteria, which are based on traditional product use, in the context of modern alternatives. The current global standard, the Pictorial Blood Assessment Chart (PBAC), diagnoses HMB at a total menstrual blood loss exceeding 80 milliliters per cycle.

The team tested 21 products—including pads, panty liners, tampons, menstrual cups, discs, and period underwear—using expired human blood from a blood bank. This approach provided a more accurate medium than saline, as real menstrual blood is a complex mixture of blood cells, proteins, and endometrial tissue, differing in viscosity and absorption characteristics.

Key Findings: Labeled vs. Actual Performance

The comparative analysis yielded specific, parameter-driven insights:

• Period Underwear: Demonstrated an actual absorption capacity of only 1-3 milliliters. This contrasts sharply with online retailer claims for similar products citing approximately 40 milliliters. Testing showed minimal performance difference between various marketed "absorbency levels" of the same underwear product line.

• "Light" Products: Pads and panty liners absorbed 3-4 milliliters; tampons absorbed 20-34 milliliters.

• "Heavy" Pads: Outperformed expectations, with a maximum actual absorption of 52 milliliters, compared to labeled ranges of 10-20 milliliters.

• Menstrual Cups and Discs: Offered the highest capacity, with one model holding up to 80 milliliters when completely filled, making them a practical choice for individuals with heavy flow.

Clinical Implications: Questioning Diagnostic Standards

The data directly challenges the parameters of current HMB diagnostic criteria. Common guidelines, such as diagnosing HMB based on saturation of a pad or tampon within 1-2 hours, may be too stringent, potentially leading to underdiagnosis. The study provides a parameter-based example: saturating two "heavy" pads (approx. 100mL) or three "heavy" tampons (approx. 90mL) in a single cycle already exceeds the 80mL diagnostic threshold for HMB.

Context: A Field Needing More Research

This study highlights the significant research gap and historical stigma surrounding menstrual health. Despite affecting hundreds of millions daily, scientific inquiry is limited. For context, annual academic publications on "erectile dysfunction" historically outpace those on "menstrual blood" by a factor of approximately two. Standardized assessment tools for menstrual health only emerged in the early 2000s.

Limitations and Future Direction

The study acknowledges limitations. Sourcing human blood for testing presents logistical and cost barriers compared to using saline. Furthermore, while superior to saline, banked blood is not identical in composition to menstrual blood. The laboratory pour method also differs from the dynamic flow process in vivo. In practice, individuals rarely wait for complete saturation before changing a product, meaning clinical assessment must consider both usage frequency and absorption degree.

Conclusion

This research provides quantified evidence of the performance gap between labeled and actual absorption of menstrual products using a human blood benchmark. Its primary significance is the clear indication that current HMB diagnostic standards may be flawed, necessitating a review based on more accurate data. Ultimately, it underscores the need to normalize and deepen scientific discourse on menstruation to improve health outcomes.