=Symptoms.= The symptom of placenta prævia is hemorrhage, occurring during the latter part of pregnancy or at the onset of labor. The cause of the hemorrhage is the separation of that part of the placenta covering the internal os, when the latter dilates, thus presenting an exposed, bleeding surface. The hemorrhage is usually so profuse that unless it is controlled, both mother and child may bleed to death. =Treatment.= Unhappily there is no preventive treatment for placenta prævia, beyond that which is included in treatment for endometritis, and good care during the preceding puerperium. [Illustration: FIG. 47.—Position of Champetier de Ribes’ bag to stop hemorrhage, from placenta prævia, by pressure. ] Since the great danger in this complication is from hemorrhage the doctor’s principal effort is directed toward its control. Infection and shock are also feared but the first step is to stop the bleeding. A common method is to stimulate the uterus to contract; that necessitates the removal of its contents, or the induction of labor. The separation of the placenta leaves open, bleeding vessels in the uterine wall and placenta, which can only be closed by pressure, until the uterus contracts on its own vessels. The doctor sometimes makes pressure with tampons of gauze, by rupturing the membranes and bringing down the presenting part of the child to press against the bleeding surface, or by introducing a rubber bag into the cervix and pumping it full of sterile water. (Fig. 47.) By means of its weight and downward traction, this bag presses against the bleeding areas and thus checks the hemorrhage. It also tends to dilate the cervix, after which the baby is sometimes born spontaneously and sometimes delivered artificially. PREMATURE SEPARATION OF A NORMALLY IMPLANTED PLACENTA. A placenta prævia, as has been explained, is abnormally situated. But it sometimes happens that a placenta that is normally placed will separate prematurely, with hemorrhage as the inevitable result. Such a hemorrhage is termed “accidental” to distinguish it from the unavoidable bleeding caused by a placenta prævia. If the blood escapes from the vagina, the hemorrhage is called “frank,” but if it is retained within the uterine cavity it is called a “concealed” hemorrhage. =Causes.= Endometritis is probably an underlying cause, though very little is definitely known on the subject. Previous pregnancies are believed to be a factor, as this accident occurs less often among women who are pregnant for the first time than among those who have borne children, and also as the frequency of the hemorrhages apparently increases with the number of previous pregnancies. Nephritis is believed to be a possible cause, as well as anemia, general ill-health, toxemia, physical shocks, and frequently recurring pregnancies.