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The use of fetal scalp blood testing originated in Germany in 1961 and required 0.25 mL of blood drawn from the fetus. [1] As one of the first methods of monitoring fetal wellbeing during labor, there were many disadvantages including the need for at least 3 cm dilation of the mother and extreme precision from the physician performing the procedure. [9]
Percutaneous umbilical cord blood sampling (PUBS), also called cordocentesis, fetal blood sampling, or umbilical vein sampling is a diagnostic genetic test that examines blood from the fetal umbilical cord to detect fetal abnormalities. [1] Fetal and maternal blood supply are typically connected in utero with one vein and two arteries to the fetus.
In the fetus, the normal range differs based on which umbilical vessel is sampled (umbilical vein pH is normally 7.25 to 7.45; umbilical artery pH is normally 7.18 to 7.38). [2] Fetal metabolic acidemia is defined as an umbilical vessel pH of less than 7.20 and a base excess of less than −8. [3]
[13] [16] [17] [18] [1] The normal pH in the fetus differs from that in the adult. In the fetus, the pH in the umbilical vein pH is normally 7.25 to 7.45 and that in the umbilical artery is normally 7.18 to 7.38. [19] Aqueous buffer solutions will react with strong acids or strong bases by absorbing excess H + ions, or OH −
The embryo is surrounded by the thin membranes of the amniotic sac, the umbilical cord is seen in the center, attaching the embryo to the placenta. The umbilical cord develops from and contains remnants of the yolk sac and allantois. It forms by the fifth week of development, replacing the yolk sac as the source of nutrients for the embryo. [2]
A blood gas test or blood gas analysis tests blood to measure blood gas tension values, it also measures blood pH, and the level and base excess of bicarbonate.The source of the blood is reflected in the name of each test; arterial blood gases come from arteries, venous blood gases come from veins and capillary blood gases come from capillaries. [1]
Delaying the clamping allows blood to flow from the placenta to the baby while the baby’s lungs fill with air.
Histopathology of placenta with increased syncytial knotting of chorionic villi, with two knots pointed out. The following characteristics of placentas have been said to be associated with placental insufficiency, however all of them occur in normal healthy placentas and full term healthy births, so none of them can be used to accurately diagnose placental insufficiency: [citation needed]