Abstract

PIP: An evaluation of the photometric alkaline hematin procedure was carried out to determine its reliability and practicality in measuring menstrual blood loss (MBL). A reliable method for quantitating MBL was necessitated in order to measure the effect of IUD design on uterine bleeding. MBL was measured in 6 women during 2-4 consecutive cycles (total of 15 cycles). Test samples of blood, either as liquid or soaked into sanitary napkins, vaginal tampons, or cotton pads were incubated at room temperature in 5% (w/v) aqueous sodium hydroxide solution. After incubation, absorbance of the brown-colored alkaline hematin was measured at 550 nm in a Perkin-Elmer Model 124 dual beam spectrophotometer against a blank of either 5% sodium hydroxide or distilled water. The quantity of blood in each sample, represented by eluted, hematin-converted hemoglobin, was determined from a standard curve relating various known volumes of incubated blood to absorbance at 550 nm (A550). Standard volumes of blood were always incubated for the same length of time as the samples. When the samples were diluted with more sodium hydroxide solution than the standards, sample absorbances were multiplied by an appropriate dilution factor. The photometric alkaline hematin procedure indicated a sensitivity to less than .1 ml of blood, within-batch precision of 5% or less (2 C.V.), and an accuracy of measuring human menstrual blood from most sanitary devices generally within plus or minus 5%. The method appeared to be specific for menstrual blood and independent of other materials in genital fluids. Menstrual discharge could be stored for at least 1 month prior to determination without alteration of results. The procudre, once optimized for the authors' purposes, was found to be very practical. The results of the study were consistent with the available literature which indicated that maximum normal menstrual blood flow is between 60 and 80 ml, and the mean is near 30 ml. Variation of measured flow between consecutive menstrual cycles in some individuals (both normal and menorrhagic) revealed the necessity for repeated measurements to properly assess average blood flow in certain cases.