Placental abruption

Question 1

What is placental abruption?

Answer 1

Bleeding at decidual-placental interface that cause partial or total placental detachment prior to delivery of the fetus
Typically over 20 weeks of gestation

Question 2

Perinatal death rate for abruption

Answer 2

12% (vs. 0.6% in non-abruption births

Majority of perinatal deaths (up to 77%) occur in utero; postnatal period deaths are related to preterm delivery

Question 3

Incidence of abruption

Answer 3

0.4-1% of pregnancies

1 review - 50% before 37 wks GA and <20% before 32 wks, but largely variable depending on the etiology

Question 4

Pathophysiology of abruption

Answer 4

Immediate cause of premature placental separation is rupture of maternal vessels in decidual basalis where it interfaces with anchoring villi of the placenta.

The accumulating blood splits decidua, separating the thin layer of decidua with its placental attachment from the uterus.

Can lead to complete or near complete separation - detached portion is unable to exchange gas and nutrients, remaining fetoplacental unit not able to compensate for loss of function, fetus becomes compromised

Question 5

Etiology of bleeding at decidual basalis

Answer 5

Clinical/epidemiologic research a lot

Mechanical events (blunt trauma or shearing of placenta due to sudden stretching or contraction of the uterine wall) - MVA (rapid accel-decel)

Severe trauma 6 fold increase in abruption

Uterine abnormalities

Cocaine use (vasoconstriction leading to ischemia) -10%

Smoking - vasoconstriction causing hypoperfusion, necrosis and hemorrhage

Uterine abnormalities (leiomyoma, bicornuate uterus - placental implantation)

Abnormality in early development of spiral arteries leading to decidual necrosis, inflammation and possible infarction

Question 6

Risk factors for abruption

Answer 6

Smoking (2.5x)
Smoking + HTN are synergistic (5x)
HTN - antihypertensive therapy does not appaer to reduce risk of abruption with chronic HTN

Question 7

Patient presentation of abruption

Answer 7

Abrupt onset of vaginal bleeding, mild to moderate abdominal or back pain, uterine contractions

Uterus is often firmy, may be rigid and tender

Question 8

Bleeding and abruption

Answer 8

blood loss may be underestimated - bleeding retained behind placenta
correlates poorly with degree of separation and not useful marker of impending fetal or maternal risk

Question 9

Clinical signs for fetal/maternal risks in abruption

Answer 9

Maternal hypotension and fetal heart rate abnormalities

Question 10

Placental separation > 50% - common consequences

Answer 10

acute disseminated intravascular coagulation (10-20% of severe abruptions with death of fetus)
fetal death

Question 11

Lab findings for abruption

Answer 11

fibrinogen - best correlation with severity of bleeding

<200 is reported to have 100% PPV of severe postpartum hemorrhage

Question 12

Confirmation of acute DIC

Answer 12

increasing thrombin generation, fibrinolysis (D-dimer)

platelet count

Question 13

Imaging

Answer 13

retroplacental hematoma is classic ultrasound finding

absence does not exclude possibility of severe abruption - blood may not collect behind uterus

Question 14

Sensitivity of abruption on US

Answer 14

only 25-50% (positive predictive value is 88%)

Question 15

Consequences

Answer 15

Maternal: related to severity of separation
Fetus: severity and GA of delivery

Question 16

Maternal consequences of abruption

Answer 16

excessive blood loss - hypovolemic shock, renal failure, ARDS, multiorgan failure, peripartum hysterectomy, DIC, death

Emergency C/S for fetal or maternal indications

Question 17

Fetal consequences of abruption

Answer 17

Perinatal morbidity and mortality related to hypoxemia, asphyxia, low birth weight, preterm delivery

Fetal growth restriction with chronic abruption

Question 18

Placental pathology

Answer 18

recent infarct - preservation of villous stromal architecture, eosinophiic degeneration of synctiotrophoblast, villous agglutination with neutrophils 96h to develop)

Question 19

Recurrence

Answer 19

5-15% recurrence (baseline of 0.4-1.3% in general population)

After 2 consecutive abruptions - risk increases to 20-25%

Risk higher after severe abruption

Question 20

Chronic abruption

Answer 20

light, chronic, intermittent bleed 0 ischemic placental disease over time - oligohydramnios, fetal growth restrictions, preeclampsia

Coagulation normal

Question 21

Diagnosis

Answer 21

Cliniacal, imaging, postpartum path studies

Question 22

Differential diagnosis of abruption

Answer 22

Labor (more gradual onset; bloody mucus before labor begins)
Placenta previa (painless vaginal bleeding - prior US)
Uterine rupture (prior hysterotomy) - sudden fetal heart abnormalities, recession of presenting part
Subchorionic hematoma (partial detachment of chorionic membranes from uterine wall - light vaginal bleeding; made before 20 weeks of gestation

Question 23

Severe acute abruption

Answer 23

• Initiate continuous fetal monitoring
• 2 large bore IV to access
• Closely monitor mother’s hemodynamic status (HR, BP, urine output) - UOP maintained above 30 ml/hour - normal BP may mask hypovolemia
• CBC, blood type, RH and coag studies - blood bank for blood replacement products
• DIC - massive transfusion protocol

Question 24

At what level to aim treatment for DIC

Answer 24

Platelet > 50 000
Fibrinogen > 100
PT/PTT < 1.5x control
Hematocrit 25-30

Question 25

After initial assessment and stabilization

Answer 25

Assess whether fetus is alive or dead

If alive, then GA and fetus status play a role in decision making

Question 26

Severe abruption at any GA and nonsevere abruption > 36 weeks

Answer 26

Delivery if mother is unstable (ongoing blood loss, hypotension), or fetal heart rate tracing is nonreassuring

Vaginal reasonable if mother is stable and tracing reassuring - if there is access to immediate CS

Prompt C/S if mother is unstable or FHR is nonreassuring - major maternal morbidity and death as risk factor with C/S in the presence of coagulopathy (cdesirable, but not always possible, to correct clotting abnormality prior to cesarean)

Question 27

Couvelaire uterus?

Answer 27

blood extravasated into myometrium - atonic and more prone to postpartum hemorrhage - may increase risk of hysterectomy

Question 28

Minor abruption 34-36wk

Answer 28

conservative treatment - close monitoring, can have increased risk for sudden, severe abruption

Question 29

Fetal demise

Answer 29

minimize maternal morbidity and mortality - vaginal delivery is acceptable