and Giffard attributed the hemorrhage to the dilata tion of the cervix, and consequent laceration of the veins. Levret was the one who first advanced a true theory of this accident. The cervix, according to him, sharing during the latter months of pregnancy in the enlargement of the rest of the uterus, grows away from the placenta, which thus becomes detached, whence the early hemorrhages that inevita bly recur during labor, because of the opening and dilatation of the cer vix. This theory, though generally adopted, was based on erroneous ob servations, and it was necessary to find another. Stoltz showed that the cervix remained absolutely intact up to the last weeks, or even days, of pregnancy, and could not by expanding give rise to the hemorrhage. Jacquemier affirmed that when the placenta was inserted over the os, its separation during the first half of pregnancy was prevented in part by its growth, which is at first very rapid, but later it becomes so stretched, that partial detachment occurs, whence the hemorrhage during the fourth, fifth and sixth months. But when the mechanical distension of the lower uterine segment is added to the enlargement of the placenta, causing it to project more or less into the pelvic cavity, the tearing increases to a very marked degree, and often results in separation of a portion of the placenta. hence the increasing frequency of hemorrhage during the seventh, eighth, and a part of the ninth month, although the os is just as much closed as it was when bleeding first took place. Levret's ex planation applies later after labor has begun; then dilatation of the cervix is the real, active cause. This theory has been attacked of late years by two authorities—Barnes, who admits that the blood comes from the uterus, and Simpson, who thinks that it is derived mostly from the placenta. The latter affirms that if the exposed uterine vessels contribute to the heinorrhage, it is only to a limited extent, and that most of the blood is derived from the placenta. Hence, at each escape of blood, a portion of the placenta is obstructed, and prevents further access of the maternal blood at the detached side; the hemorrhage accordingly ceases as soon as the placenta is completely separated. This view is incorrect, since the blood comes from the uterus, and not from the placenta, as has been proved by all observers, in cases in which the bleeding continued after the expulsion of the placenta.
Barnes offers the following explanation: In common with Stoltz, he be lieves that the first hemorrhage is due to excessive development of the placenta, as compared with that of the cervix. Under the influence of the monthly congestion the uterus and placenta are engorged with blood, and the latter swells and becomes too large for the surface to which it is attached; it becomes separated at the edges of the os and the blood pours out. Then, in consequence of the irritation which this partial detach ment produces, the uterus contracts, and thus a still larger portion of the placenta is separated, but this separation is always confined to the cervi cal zone. The strong contraction of the uterus is the true cause of the cessation of the hemorrhage. Barnes divides the internal surface of the uterus into three zones (Fig. 149): The superior polar circle or fun due, which is free from danger; the middle zone, attachment of the pla centa to which occasions risk of post-partum hemorrhage; and (lie inferior or cervical zone or region of danger. Any portion of the placenta inserted
in the latter may be detached prematurely, because the os must enlarge to give passage to the child, and this enlargement does not allow the pla centa to remain fixed. As long as the separation does not extend to the border of the cervical zone, the hemorrhage continues; soon as this limit is reached it stops, if the uterus contracts strongly. Now, accord ing to him, there are two things that prevent contraction, the fact that the uterus has not reached its full development, and the diminution of the vital force in consequence of loss of blood. Barnes affirms that the cer vix dilates slowly in these cases, but it is not because it is rigid and resist ant, but rather because the uterine contractions continue for a long time to be feeble and irregular. In the 15 or 16 cases observed by me, I have never been able to demonstrate this so-called anatomical resistance of the cervix, which he describes.
There are thus two theories: In the one the blood comes from the pla centa and its vessels, and which is not admissible as an exclusive theory; in the other the blood comes from the uterus, according to certain authors during labor, and according to Barnes the hemorrhage necessarily ceases when labor has progressed to a certain extent.
Legroux's conclusions (1855) express the same idea, viz.: Hemorrhage due to separation of the placenta takes place during repose of the uterus, but ceases when the organ contracts, and does not recur if the contraction is permanent. The hemorrhage is almost entirely uterine, the placenta contributing only a small share of the loss, which may affect the life of the child, but not that of the mother. It becomes entirely uterine after the death of the fwtus.
Matthews Duncan believes that hemorrhages from placenta przevia dur ing the last three months of pregnancy are often unaccompanied by sepa ration of the placenta, although this doubtless takes place in some cases. hemorrhage in his opinion may occur in four ways: 1. By the rupture of a utero-placental vessel, at the border of the os internum. 2. By the rupture cf a marginal utcro-placental sinus in the area of spontaneous detachment, in partial implantation. 3. By the partial separation of the placenta in consequence of traumatism. 4. By its partial separation from uterine contractions, which cause slight dilatation of the os. Spiegelberg adopts this view.
4. Hemorrhages during Labor.
All authorities agree that hemorrhage during labor is inevitable in cases of abnormal insertion, and they attribute it to separation of the placenta. Jacquemier says if labor sometimes proceeds without accidents in these cases, it is because the placenta was either completely detached, or at least it was so attached that dilatation proceeded without sepa rating it any further. Moreau's theory that hemorrhage ceases after the death of the fetus is negatived by many facts. Most writers believe that the hemorrhages increase at the return of each pain; Barnes, Judell and myself, adopt this opinion. Duncan says that the uterine contrac tion diminishes the calibre of the vessels, and thus diminishes the hem orrhage; Schroeder believes that the uterine wall glides away from the placenta during the dilatation of the cervix, as long as the membranes are intact, but after they are ruptured the placenta can follow the uterine wall in its movement of ascension, and there is no danger of sep aration.