Placental abruption Flashcards
What is placental abruption?
Bleeding at decidual-placental interface that cause partial or total placental detachment prior to delivery of the fetus
Typically over 20 weeks of gestation
Perinatal death rate for abruption
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
Incidence of abruption
0.4-1% of pregnancies
1 review - 50% before 37 wks GA and <20% before 32 wks, but largely variable depending on the etiology
Pathophysiology of abruption
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
Etiology of bleeding at decidual basalis
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
Risk factors for abruption
Smoking (2.5x)
Smoking + HTN are synergistic (5x)
HTN - antihypertensive therapy does not appaer to reduce risk of abruption with chronic HTN
Patient presentation of abruption
Abrupt onset of vaginal bleeding, mild to moderate abdominal or back pain, uterine contractions
Uterus is often firmy, may be rigid and tender
Bleeding and abruption
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
Clinical signs for fetal/maternal risks in abruption
Maternal hypotension and fetal heart rate abnormalities
Placental separation > 50% - common consequences
acute disseminated intravascular coagulation (10-20% of severe abruptions with death of fetus)
fetal death
Lab findings for abruption
fibrinogen - best correlation with severity of bleeding
<200 is reported to have 100% PPV of severe postpartum hemorrhage
Confirmation of acute DIC
increasing thrombin generation, fibrinolysis (D-dimer)
platelet count
Imaging
retroplacental hematoma is classic ultrasound finding
absence does not exclude possibility of severe abruption - blood may not collect behind uterus
Sensitivity of abruption on US
only 25-50% (positive predictive value is 88%)
Consequences
Maternal: related to severity of separation
Fetus: severity and GA of delivery
Maternal consequences of abruption
excessive blood loss - hypovolemic shock, renal failure, ARDS, multiorgan failure, peripartum hysterectomy, DIC, death
Emergency C/S for fetal or maternal indications
Fetal consequences of abruption
Perinatal morbidity and mortality related to hypoxemia, asphyxia, low birth weight, preterm delivery
Fetal growth restriction with chronic abruption
Placental pathology
recent infarct - preservation of villous stromal architecture, eosinophiic degeneration of synctiotrophoblast, villous agglutination with neutrophils 96h to develop)
Recurrence
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
Chronic abruption
light, chronic, intermittent bleed 0 ischemic placental disease over time - oligohydramnios, fetal growth restrictions, preeclampsia
Coagulation normal
Diagnosis
Cliniacal, imaging, postpartum path studies
Differential diagnosis of abruption
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
Severe acute abruption
- 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
At what level to aim treatment for DIC
Platelet > 50 000
Fibrinogen > 100
PT/PTT < 1.5x control
Hematocrit 25-30
After initial assessment and stabilization
Assess whether fetus is alive or dead
If alive, then GA and fetus status play a role in decision making
Severe abruption at any GA and nonsevere abruption > 36 weeks
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)
Couvelaire uterus?
blood extravasated into myometrium - atonic and more prone to postpartum hemorrhage - may increase risk of hysterectomy
Minor abruption 34-36wk
conservative treatment - close monitoring, can have increased risk for sudden, severe abruption
Fetal demise
minimize maternal morbidity and mortality - vaginal delivery is acceptable
