All of these factors can lead to an underappreciation of the magnitude of hemorrhage over time. he efects of hemorrhage depend to a considerable degree on the maternal nonpregnant blood volume and the corresponding degree of pregnancyinduced hypervolemia. For this and other reasons, hypovolemia may not be recognized until very late. A treacherous eature of pospartum hemorrhage is the ailure of the pulse and blood pressure to undergo more than moderate alterations until large amounts of blood have been lost. The normotensive woman initially may actually become somewhat hypertensive from catecholamine release in response to hemorrhage. And importantly, women with preeclampsia may become "normotensive" despite remarkable hypovolemia.
Some gravidas may be particularly susceptible to hemorrhage because their blood volume expansion is less than expected. This situation is most commonly encountered in small womeneven those with normal pregnancy-induced hypervolemia. Women with severe preeclampsia or eclampsia are also more vulnerable to hemorrhage because they frequently do not have a normal blood volume accrual. Specifically, Zeeman and associates (2009) documented a mean increase above nonpregnant volume of only 10 percent in eclamptic women (Chap. 40, p. 718). A third example is the moderate-to-severe curtailing of pregnancy-induced volume expansion in women with chronic renal insuiciency (Chap. 53, p. 1034). When excessive hemorrhage is suspected in these high-risk women, cystalloid and blood are prompty administered or suspected hypovolemia.
The most frequent cause of obstetrical hemorrhage is failure of the uterus to contract suiciently after delivery and to arrest bleeding from vessels at the placental implantation site (p. 755). That said, some bleeding is inevitable during thirdstage labor as the placenta begins to separate. Blood from the implantation site may escape into the vagina immediately-the Duncan mechanism of placental separation, or it remains concealed behind the placenta and membranes until the placenta is delivered-the Schultze mechanism. After signs of placental separation, the uterus should be massaged if it is not contracted irmly, and placental descent is indicated by a slack umbilical cord. Importanty, separation and delivey of the placenta by cord traction, especialy when the uterus is atonic, may cause uterine inversion.
If heavy bleeding persists after delivery of the newborn and while the placenta remains partially or totally attached, then manual placental removal is indicated (Cummings, 2016; Frolova, 2016). For this, adequate analgesia is mandatory, and aseptic surgical technique should be used. As illustrated in
Figure 41-3, the fingertips of one hand, with fingers approxi mated, are insinuated between the uterine wall and placenta. A sweeping forward motion in this plane will peel the placenta of its uterine attachmenc. After its removal, trailing membranes are carefully teased free from the decidua using ring forceps as needed. Another method to clear membranes is to wipe out the uterine cavity with a gauze-wrapped hand. Most recommend
FIGURE 41 -3 Manual removal of placenta. A. One hand grasps the fundus. The other hand is inserted into the uterine cavity, and the fingers are swept from side to side as they are advanced. B. When the placenta has become detached, it is grasped and removed.
removal (World Health Organization, 2015).