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Fetal hemoglobin, or foetal haemoglobin (also hemoglobin F, HbF, or α 2 γ 2) is the main oxygen carrier protein in the human fetus.Hemoglobin F is found in fetal red blood cells, and is involved in transporting oxygen from the mother's bloodstream to organs and tissues in the fetus.
The oxygen–hemoglobin dissociation curve, also called the oxyhemoglobin dissociation curve or oxygen dissociation curve (ODC), is a curve that plots the proportion of hemoglobin in its saturated (oxygen-laden) form on the vertical axis against the prevailing oxygen tension on the horizontal axis. This curve is an important tool for ...
The rabbit test became a widely used bioassay (animal-based test) to test for pregnancy. The term "rabbit test" was first recorded in 1949, and was the origin of a common euphemism, "the rabbit died", for a positive pregnancy test. [4] The phrase was, in fact, based on a common misconception about the test.
The binding of oxygen to methemoglobin results in an increased affinity for oxygen in the remaining heme sites that are in ferrous state within the same tetrameric hemoglobin unit. [17] This leads to an overall reduced ability of the red blood cell to release oxygen to tissues, with the associated oxygen–hemoglobin dissociation curve ...
The hemoglobin alkaline denaturation test can detect the presence of maternal blood, which is indicated by a color change from red to brown when the sample is added to alkali reagent. [ 13 ] [ 14 ] Blood typing would also detect maternal blood, as the I antigen only occurs in adults. [ 12 ]
The results of the blood test are then combined with the NT ultrasound measurements, maternal age, and gestational age of the fetus to yield a risk score for Down syndrome, trisomy 18, and trisomy 13. First Trimester Combined Test has a sensitivity (i.e. detection rate for abnormalities) of 82–87% and a false-positive rate of around 5%. [74] [75]
The KB test is the standard method of quantitating fetal–maternal hemorrhage (FMH). It takes advantage of the differential resistance of fetal hemoglobin to acid. A standard blood smear is prepared from the mother's blood and exposed to an acid bath.
Embryonic hemoglobin is a tetramer produced in the blood islands in the embryonic yolk sac during the mesoblastic stage (from 3rd week of pregnancy until 3 months). The protein is commonly referred to as hemoglobin ε. Chromosomal abnormalities can lead to a delay in switching from embryonic hemoglobin. [3]