The more energetic and regular the pains, the later the rupture of the membranes, the more normal the anatomy of the cervix, the more ad vantageous the fcetal position, and the more regular the conformation of the pelvis, the better and the quicker will dilatation occur. The head, in passing through the cervix, produces a laceration of its border, which, although.of little importance in most cases, may extend to a certain height, and may even, in some instances, assume such proportions as to seriously endanger the woman's life. (Vide Rupture of the Uterus). The fre quency of the position L. O. A. explains why this laceration occurs, ordi narily, on the left. Repeated at each confinement, these lacerations impart to the cervices of multiparEe their characteristic aspect, as the result of cicatrization, and of the subsequent changes in the cervical tissues.
5. Len corrhay.
The vaginal and cervical glands are considerably hypertrophied in pregnancy, and their secretions notably augmented. This gives rise to leucorrhcea, which increases in proportion as pregnancy advances. ( Vide Chapter concerning Anatomical Modifications of the Genital Organs). The thick, viscid mucus, secreted by the cervical glands, accumulates in the cervix, constituting the so-called cervical gelatinous plug. As soon as the cervix is definitively obliterated, and when dilatation is about to begin, the organ, opening, allows the mucous plug to escape, which, mixed with the vaginal secretions, issues from the vulva in the form of a yellowish fluid containing more or less blood. In certain cases the quan tity of blood is sufficient to stain the woman's linen. This is the so-called " show." Tarnier holds that a certain quantity of amniotic fluid often mingles with this discharge, having transuded through the still unrup tured membranes. The experiments upon which Tarnier bases his de ductions regarding the transudation of amniotic fluid, having been made with membranes obtained after delivery, and under conditions quite different from the physiological ones, do not seem conclusive to us. It seems much more natural, to us, to refer the moisture of the vagina, during labor, to the vaginal secretions. In Tarnier's experiments, indeed, the pressure exerted on the membranes was continuous, while, in labor, the pressure is short and intermittent, since it results from uterine con tractions.
6. The Bay of Waters.—Rupture of the Membranes.
The bag of waters consists of that part of the membranes which, dis tented by the amniotic fluid, projects through the more or less dilated cervix. It forms as soon as the pains have sufficiently dilated the cervix to allow the membranes to become engaged in its orifice. Its enlarge ment is, in general, dependent upon the degree of cervical dilatation.
Tense, resisting, prominent during the pain, which forces more and more of the amniotic fluid into its cavity, the bag of waters is, during the in tervals of contraction, flaccid and soft. It may then be indented by the finger, which thus takes cognizance of the presentation, and, often, of the position. The bag of waters is, as Depaul remarks, essentially tem porary, even as the cause which produces it, and only becomes permanent in the pathological cases where the uterine contractility has assumed the same character. The shape of the bag of waters is not constant, depend ing not only on the shape of the cervix. but upon the variety of the pre sentation and upon the extent to which engagement has taken place. The bag of waters is generally hemispherical, and its size is greater in proportion as the presentation is abnormal. It is, thus, small in head presentations, and is more voluminous in less favorable presentations and in cases of delayed engagement. Spherical or hemispherical in head pre sentations, it is often oval in presentations of the trunk, and in obliquity of the uterus. In pelvic presentations it is cylindrical. The bag some time resembles an ampulla, compressed and pediculated, at its base, by the undilated cervix. The bag is double under two conditions. The usual condition is in cases of twin pregnancy. The other, more rare, has been reported by Campbell, and we have seen two examples. The obstetrician himself ruptures the membranes, or witnesses their rupture, and, nevertheless, a second bag of waters is formed, after a time. This bag either bursts spontaneously or the accousheur is forced to rupture it_ The practical inferences to be drawn from the shape of the bag of waters suggest themselves. Every time that the physician encounters a volu minous bag of waters he must, above all, make sure of the diagnosis, and, if it is abnormal, as is often the case, he should seek to prevent the rup ture of the membranes, so as to retain the largest possible quantity of amniotic fluid, the presence of which frequently facilitates the interven tion of the accoucheur (Version). Certain German obstetricians, in order to prevent the rupture of the membranes in these cases, do not hesitate to introduce a bag of rubber distended with water (Colpeurynter of Braun) into the vagina, to support the bag of waters and to avoid its rupture. In the article on the " Placenta" we stated that, in certain cases, the umbilical vessels ramify on the membranes (insertio velamentosa). In these cases spontaneous or artificial rupture exposes the Rails to a hemor rhage which may be mortal if the rupture involves one of these vessels.