RESUMO
OBJECTIVE: To validate the semiautomated alkaline hematin technique for rapid measurement of menstrual blood loss on ultrathin sanitary towels with a superabsorbent polymer component. DESIGN: Laboratory study using simulated menstrual fluid (SMF) and Always Ultra Normal, Long, and Night "with wings" sanitary towels. SETTING: Laboratorium für Klinische Forschung, Germany. PATIENT(S): None. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Linearity and blood recovery over a range of SMF volumes applied to towels, the lower limit of reliable detection, and the effect of storing soiled towels for up to 5 weeks at 20°C and 4°C before analysis, were determined. Recovery from 63 SMF samples comprising between 5% to 100% blood and 0.05-35 mL applied volume was compared with duplicates analyzed at Keele Menstrual Disorders Laboratory (manual reference method). RESULT(S): Linearity was confirmed, and ≥85% recovery was reproducibly achieved at up to 30 mL applied blood at all tested SMF compositions, except at low volume or high dilution equivalent to <4 mL blood. Samples could be stored for 3 weeks at 4°C without loss of recovery. Linear regression analysis showed good agreement with the reference method. CONCLUSION(S): The semiautomated alkaline hematin technique is a reliable method for measuring menstrual blood loss from Always Ultra sanitary towels containing superabsorbent polymers.
