Validation of a rapid alkaline hematin technique to measure menstrual blood loss on feminine towels containing superabsorbent polymers  Julia L. Magnay, M.Sc., Gerrit Schönicke, M.D., Tracy M. Nevatte, Ph.D., Shaughn O’Brien, D.Sc., Wolfgang Junge, M.D.  Fertility and Sterility  Volume 96, Issue 2, Pages 394-398 (August 2011) DOI: 10.1016/j.fertnstert.2011.05.096 Copyright © 2011 American Society for Reproductive Medicine Terms and Conditions

Figure 1 Calibration master curves for the measurement of hemoglobin (as alkaline hematin) extracted from Always Ultra normal, long, and night towels. The dashed lines represent the absorbance of hemoglobin diluted in NaOH but not applied to towels. Fertility and Sterility 2011 96, 394-398DOI: (10.1016/j.fertnstert.2011.05.096) Copyright © 2011 American Society for Reproductive Medicine Terms and Conditions

Figure 2 Linear regression analysis of blood recovered from known volumes and percent compositions of simulated menstrual fluid (SMF) applied to Always Ultra normal, long, and night towels. Volumes tested contained 0.05 to 35 mL and 5% to 100% whole blood; n = 63 towels (21 of each type). Composite data from all towel types are shown. Fertility and Sterility 2011 96, 394-398DOI: (10.1016/j.fertnstert.2011.05.096) Copyright © 2011 American Society for Reproductive Medicine Terms and Conditions

Figure 3 Bland-Altman analysis of mean blood recovered by the manual reference method and the semiautomated method versus the difference in recovery between the methods. The horizontal dotted lines denote the 95% limits of agreement; n = 63 towels (21 of each type). Composite data from all towel types are shown. Fertility and Sterility 2011 96, 394-398DOI: (10.1016/j.fertnstert.2011.05.096) Copyright © 2011 American Society for Reproductive Medicine Terms and Conditions