Estimating menstrual blood loss in women with normal and excessive menstrual fluid volume

OBJECTIVE: To examine the relationship between total fluid volume at menstruation and the volume of blood loss, and to assess the feasibility of using total fluid volume to estimate menstrual blood loss. METHODS: Fifty-three women were studied over two menstrual periods each. Hemoglobin in menstrual pads and tampons was measured using the alkaline hematin technique; total menstrual fluid volume was simultaneously measured using a weighing technique and meticulous care to avoid evaporation. RESULTS: Despite period-to-period change in measured total menstrual fluid and menstrual blood loss volumes, there was a significant correlation between total fluid volume and blood loss (r=.93, P<.001). Blood comprised 48% of total menstrual flow for women with moderately heavy blood loss (>60 mL) and 50% for women with excessive blood loss (>100 mL). Regression estimation of blood loss from total fluid volume was reasonably accurate. For clinical purposes, estimated blood volumes correctly classified 98% of periods in terms of actual blood loss as normal (<60 mL blood), moderately heavy (60-100 mL), or excessive (>100 mL). CONCLUSION: If total fluid volume is measured carefully, the estimate of actual blood loss is sufficiently accurate for clinical purposes. This simple technique has considerable clinical potential, and inexpensive commercial packs for this purpose could easily be developed. (Obstet Gynecol 2001;98:806-14. (C) 2001 by the American College of Obstetricians and Gynecologists).