14 Postpartum Hemorrhage on Labor and Delivery.pdf - Vtr

106 Mhyre
While the incidence of antepartum hemorrhage appears
to be relatively stable, postpartum hemorrhage is increasing
in developed countries around the globe. 7–11 In the
United States between 1994 and 2006, rates of postpartum
hemorrhage increased 30%, almost entirely attributable to
increases in postpartum uterine atony. The proportion of
all US deliveries complicated by the need for a blood
transfusion increased 90% between 1998 and 2005 to
0.5% of all deliveries. 10 Exposure to blood products is
only one of a number of hemorrhage-related morbidities,
including anemia, disseminated intravascular coagulopathy,
myocardial ischemia, respiratory failure, renal failure,
secondary surgical procedures, fertility loss, and
delayed functional recovery postpartum. 12
Peripartum hysterectomy increased 15% in the United
States between 1994 and 2007, to a rate of 1 in 1,200
deliveries. 13 Placenta accreta, with or without placenta
previa, leads to approximately half of all peripartum hysterectomies,
and rates have increased in conjunction with
the burgeoning population of pregnant women with previous
cesarean deliveries. Hysterectomy attributed to uterine
atony more than doubled, and currently accounts for
one third of all peripartum hysterectomies. Meanwhile,
hysterectomies due to uterine rupture have become vanishingly
rare as the rates of vaginal birth after cesarean
delivery have plummeted.
The shift toward cesarean birth, up to 33% of all births
in 2009, underlies the increasing rates of abnormal placentation,
uterine atony, and postpartum hemorrhage. <strong>14</strong>
Other factors include: (1) increasing population rates of
obesity, 15 multiple gestation, 11 and advanced maternal age;
(2) increasing rates of induction of labor 16 ; and (3) increasing
use of oxytocin for induction and/or augmentation
of labor. Between 1990 and 2006, inductions of labor increased
from 10% to 22% of all US births 17 and may be as
high as 44% among women attempting to deliver vaginally.
18 Prolonged exposure to oxytocin infusions downregulates
oxytocin receptors in the lower uterine segment. 19
There appears to be a dose–response relationship between
the oxytocin area under the curve and the risk of postpartum
hemorrhage attributed to uterine atony. 20
Globally, hemorrhage is the leading cause of maternal
mortality, accounting for 25% of all maternal deaths, or an
estimated 100,000 deaths per year. 21,22 In the United
States, over the past 25 years, cause-specific mortality attributed
to obstetric hemorrhage has declined 30% from
2.6 to 1.8 per 100,000 live births, 2 and currently accounts
for 13% of all maternal deaths.
While hemorrhage is no longer the leading cause of
maternal death in the United States, it remains among the
most preventable. 23 In California, between 2002 and
2003, hemorrhage accounted for just 10% of pregnancyrelated
deaths, but in 70% of these cases, improved clinical
care would have had a good or strong chance to alter the
fatal outcome. 5 This rate of potential preventability was
higher than for any other condition and established hemorrhage
as a top priority for the California Maternal
Quality Care Collaborative (CMQCC). Consequently,
CMQCC developed the Obstetric <strong>Hemorrhage</strong> Toolkit
and deployed a statewide campaign ‘‘to improve California
hospital capabilities and resources for responding
to obstetric hemorrhage by increasing the use of protocols
and drills and by improving availability of and training in
standard and state-of-the-art medical, surgical and blood
replacement options.’’ 5
ANTICIPATED HEMORRHAGE
Antenatal risk assessment and targeted preparation are
crucial. Even with the physiological anemia of pregnancy,
a hematocrit less than 32% should be treated with oral
iron, intravenous iron, or even erythropoietin to reduce the
possible need for postpartum blood transfusion. It is important
to identify patients with special considerations,
including: (1) women with abnormal placentation; (2)
those with inherited coagulation disorders; and (3) those
who refuse blood products.
Even with the physiological anemia of
pregnancy, a hematocrit less than 32% should
be treated with oral iron, intravenous iron, or
even erythropoietin to reduce the possible
need for postpartum blood transfusion.
Special Considerations
Placenta Accreta. With placenta accreta, the decidua
basalis is absent, and the placenta adheres to a floor of
uterine myometrium. With placenta increta, chorionic villi
invade into the myometrium. With percreta, the placenta
penetrates the uterine serosa and may even grow into other
pelvic structures, most commonly the bladder. Decidual
deficiency increases vulnerability to abnormal placental
adherence and is most commonly observed at the site of a
uterine scar, in the lower uterine segment around the internal
cervical os, and over a uterine fibroid. As a result,
prior cesarean delivery, especially in the setting of an anterior
placenta or placenta previa, is the most important
risk factor for placenta accreta. 24 It is less commonly seen
after other uterine surgeries, advanced maternal age, grand
multiparity, uterine fibroids, or in vitro fertilization. Frank
hematuria in pregnancy is most often due to urinary tract
infection or nephrolithiasis, but in the setting of these other
risk factors, should be considered to be placenta percreta
invading the bladder until imaging proves otherwise.
Optimal surgical management of placenta accreta is
directed toward delivering the neonate, then closing the
uterus with the placenta left in situ, followed by planned
peripartum hysterectomy. When the area of accreta is
small, a trial of spontaneous placental separation may be