The specific gravity of the blood in pregnancy and in the puerperium: A study of seventy-five patients

Abstract

1.a. Low specific gravity values may be of aid in differentiating between pregnancy and uncomplicated tumor of the uterus.2.b. When the mother's blood density falls below 1.040, the complications of pregnancy and of the puerperium should be looked for.3.c. One reason for the increased anemia of the puerperium may be the attendant hemorrhage at delivery. Another reason may be that active lactation may alter the water and mineral balance so as to prolong and intensify the anemia throughout the nursing period, such anemia diminishing as lactation diminishes.4.d. A teleologic theory as to the origin of amniotic fluid: Sakuma7 injected 10 to 20 c.c. of 1 per cent to 2 per cent solutions of pigments into the ears of gravid rabbits. He found that only the acid types of pigments (trypan red, trypan blue, Congo red, rose bengal, and one or two others) passed through the amniotic epithelium. The pigment was found in the amniotic epithelium, in the amniotic fluid, in the fetal intestines, but not in the kidney substance of the fetus. He concludes that the passage of the pigment is brought about directly from the maternal body and not by excretion on the part of the fetus.The anemia of pregnancy is apparently at its height during the seventh month of gestation. In this connection it is of interest to note that Kamei8 determined the specific gravity of amniotic fluid in the chick and found it greatest toward the end of embryonic development. This may have some bearing on the nutrition of the embryo, possibly the mineral supply, an increase of which in the amniotic fluid would raise its density, a withdrawal of which from the mother's blood stream would lower her blood density.In a previous publication3 I commented upon the specific gravity of the blood in 14 cases of fluid collections. All the cases, eight in number, in that series which exhibited blood densities below 1.050 presented free fluid in serous cavities. I was quite impressed by these findings and felt at the time that some extraordinary changes must take place in blood density before free fluid finds its way into serous cavities.If it is true that the specific gravity of the blood must be altered downward in order to effect a transudation of free fluid into serous cavities, then it would seem that the anemia of pregnancy must be a true physiologic phenomenon, one of the objects of which is to bring about the transudation of amniotic fluid through the amniotic epithelium.5.e. The results by the falling drop technic lend themselves to comparison with the sedimentation test in pregnancy and in the puerperium. Bland, Goldstein, and First9 have studied a large series of cases. Suffice it to say that the results by both methods are in fair agreement, the practical advantage, I feel, lying with the falling drop method because the determination may be made in two minutes' time.