OBSTETRIC HEMORRHAGE
Although most patients tolerate the normal blood loss associated
with delivery without hemodynamic consequences,
Figure 58-16
Illustration depicting degrees of abruptio placentae.
A, Concealed hemorrhage. B,
External hemorrhage. C, Complete placental separation.
(Redrawn from Bonica JJ, Johnson WL: Placenta previa, abruptio placentae
or rupture of the uterus. In Bonica JJ [ed]: Principles
and Practice of Obstetric Analgesia and Anesthesia, vol 2, 1st ed. Philadelphia,
FA Davis, 1969, p. 1164.)
occasionally blood loss may be excessive and lead to maternal and fetal compromise.
The most common causes of third trimester bleeding are placenta previa, abruptio
placentae, and uterine rupture. Postpartum hemorrhage, which complicates approximately
10% of deliveries, is most often due to uterine atony, retained placenta, placenta
accreta, and uterine inversion.
Placental Abruption
Placental abruption, a partial or complete separation of the placenta
before delivery of the fetus, is estimated to occur in 1.3% to 1.6% of pregnancies.
Figure 58-16
illustrates
placental abruption in its various forms. Preexisting conditions such as chronic
hypertension, pregnancy-induced hypertension, preeclampsia, maternal cocaine use,
excessive alcohol intake, smoking, and a previous history of abruption are all risk
factors associated with placental abruption.
Placental abruption may be manifested as vaginal bleeding and
uterine tenderness. However, as shown in Figure
58-16
, blood loss can often be underestimated because of the potential
for substantial hemorrhage
Figure 58-17
Types of placenta previa. (Redrawn from Suresh
MS, Belfort MA: Antepartum hemorrhage. In Datta
S [ed]: Anesthetic and Obstetric Management of High Risk Pregnancy, 2nd ed. St
Louis, CV Mosby, 1996, p 93. Illustration copyright 1995. Baylor College of Medicine.)
concealed behind the placenta. Abruption may be mild, moderate, or severe, depending
on the degree of placental separation. DIC may occur with abruptio placentae, and
its incidence may be as great as 30% with an abruption large enough to result in
fetal death.[259]
Obstetric management depends on the severity of bleeding and fetal
status. Large-bore intravenous access should be established on admission and blood
samples drawn for baseline hematocrit, coagulation studies, blood typing, and cross-matching.
Treatment of associated DIC involves delivery of the fetus and placenta, restoration
of maternal blood volume, and correction of coagulation with the use of blood components.
If an operative procedure is considered necessary, general endotracheal anesthesia
is preferable to regional anesthesia in women with hemodynamic instability or coagulopathy.
Direct arterial blood pressure and central venous pressure monitoring is useful
to guide volume resuscitation.
