The Placenta, or After-Birth—The Membranes—Management of the After-Birth—Rules for Extracting it—Of Flooding after Delivery.
In the preceding letter, I spoke of the first two stages of labor. The last, which refers to the birth, or expulsion of the placenta and membranes, I now propose considering.
First, I must say something of the nature and office of what is termed the after-birth.
THE PLACENTA AND UMBILICAL CORD.
The placenta, or after-birth, is of different forms in different animals. In the human subject, “it is a flat, circular body, about six inches in diameter, and about one inch and a half in thickness at the center, becoming thinner toward the circumference. Usually in the center, but sometimes at or near the edge, we find the insertion of the funis, or umbilical cord, the vessels of which immediately ramify in a divergent manner upon the surface of the organ.”
From Dr. Maunsel, of Dublin, I make the following quotation, in regard to the office of this viscus:
“The uses of the placenta appear to be in some degree analogous to those of the lungs and stomach of the breathing animal. The blood passes into it from the hypogastric arteries, and after a very free circulation through it, returns by the umbilical vein directly to the heart. The circulation continues until respiration is established, when it ceases spontaneously, and any interruption of it, before the latter process has commenced, is immediately fatal. From these facts we are warranted in inferring that a change necessary to life (probably oxygenation) is produced in the placenta, although the nature of that change is obscure, and the relative properties of the blood in the umbilical arteries and veins not at all known. That the organ in question not only revivifies the blood, but also elaborates new vital fluid, thus performing a function analogous to that of the stomach, can only be inferred from the absence of any other source from whence the fetus could obtain materials for growth and support.”
THE MEMBRANES.
These are expanded from the edge of the placenta, in connection with which they form a complete involucrum of the fetus and waters, and at the same time a lining for the uterus. The membranes grow and expand in the same proportion as the fetus, and when expelled after the birth has taken place, are, in connection with the placenta, termed the secundines.