Fetal–maternal hemorrhage severity estimation To determine if a positive test for FMH indicates the likely cause of fetal death, the percent of total fetal blood volume lost should be calculated, making appropriate adjustments based on the following known relationships: * the size of a fetal red blood cell is 1.22 times that of an adult red blood cell; * the KB stain is known to have a mean success rate of 92% in detecting fetal red blood cells; * in a woman at or near term in her pregnancy, the mean volume of maternal red blood cells is approximately 1800 ml; * the mean fetal hematocrit is 50%; and * at stillbirth, the mean fetal blood volume is These constraints can then be applied to yield the formula where * is the percentage of fetal blood lost; * is the observed number of fetal red blood cells; * is the observed number of maternal red blood cells (N.B. we have that , where is the total observed number of red blood cells, both maternal and fetal); * is the stillbirth weight of the fetus in kilograms. Number of RhD vials An estimate of the required number of Rho(D) immune globulin vials may assume the following equations: * Volume (mL) of Fetal Blood = % Fetal Cells x 50 * Number of Vials of 300 mcg RhIG Required = Volume of Fetal Blood/30mL Combining those two equations results in: * Number of vials = % Fetal Cells x 50 / 30 This is approximately equal to: * Number of vials = % Fetal Cells x 1.7 Practically, if the number to the right of the decimal point is ≥5, it is rounded up to add one vial. Stillbirth resolution Suppose that a KB stain is performed and total red blood cells are observed, of which are found to be fetal red blood cells. Suppose further that the stillbirth weight of the fetus under consideration is . Then we would conclude that the total percentage of fetal blood lost is approximately: to five significant digits. We would hence conclude that the fetus under consideration lost 66.667% (two-thirds) of its blood via FMH. Generally, stillbirth is highly probable for any value of , particularly if the fetus abruptly loses this much blood; in this example, we would hence be likely to suspect FMH as the cause of the stillbirth. It is important to note, however, that such a diagnosis is still not completely conclusive; fetuses losing large quantities of blood over long periods of time are able to compensate for this slower blood loss; since the KB stain tells us nothing with regard to the level of acuity of FMH. This means that it is not possible to entirely correlate a positive KB stain and high with a stillbirth, though in many cases, given other information, such as known hereditary complications of pregnancy, extremely high positive correlation coefficients<unk> en FMH and stillbirth have been observed.
Kleihauer–Betke test
Kurzrock–Miller test
Poppy seed test
Galeazzi test
Conconi test
Beutler test
Czermak–Hering test
Yeoman's test