Placenta Previa

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Placenta Previa

• Hai Ho, MD
• Department of Family Practice

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What is placenta previa?

• Implantation of placenta over cervical os

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Types of placenta previa
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Who are at risk for placenta previa?

• Endometrial scarring of upper segment of uterus
  implantation in lower uterine segment
• Prior DC or C-section
• Multiparity
• Advance age independent risk factor vs.
  multiparity

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Who are at risk for placenta previa?

• Reduction in uteroplacental oxygen or nutrient
  delivery compensation by increasing placental
  surface area
• Male
• High altitude
• Maternal smoking

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Factors that determine persistence of placenta
previa?

• Time of diagnosis or onset of symptoms
• Location of placenta previa

Placental Migration
Repeat ultrasound at 24 28 weeks gestation
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Clinical presentations?

• Painless vaginal bleeding 70-80
• 1/3 prior to 30 weeks
• Mostly during third trimester shearing force
  from lower uterine segment growth and cervical
  dilation
• Sexual intercourse
• Uterine contraction 10-20

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Fetal complications?

• Malpresentation
• Preterm premature rupture of membrane

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Diagnostic test?

• Ultrasound

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Placenta Previa ultrasound
Placenta
Bladder
Cervix
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Placenta Previa ultrasound
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Placenta accreta?

• Abnormal attachment of the placenta to the
  uterine wall (decidua) such that the chorionic
  villi invade abnormally into the myometrium
• Primary deficiency of or secondary loss of
  decidual elements (decidua basalis)
• Associated with placenta previa in 5-10 of the
  case
• Proportional to the number of prior Cesarean
  sections

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Variations of placenta accreta
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Placenta accreta ultrasound
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Vasa Previa?
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Vasa Previa
Velamentous insertion
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Vasa Previa
Velamentous insertion
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Vasa Previa
Velamentous insertion
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Vasa Previa

• Rupture
• Compression of vessels
• Perinatal mortality rate 50 75

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Management of placenta previa?

• Individualized based on (not much evidence)
• Gestational age
• Amount of bleeding
• Fetal condition and presentation

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Preterm with minimal or resolved bleeding

• Expectant management bed rest with bathroom
  privilege
• Periodic maternal hematocrit
• Prophylactic transfusion to maintain hematocrit gt
  30 only with continuous low-grade bleeding with
  falling hematocrit unresponsive to iron therapy

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Preterm with minimal or resolved bleeding

• Fetal heart rate monitoring only with active
  bleeding
• Ultrasound every 3 weeks fetal growth, AFI,
  placenta location
• Rhogam for RhD-negative mother

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Preterm with minimal or resolved bleeding

• Amniocentesis weekly starting at 36 weeks to
  assess lung maturity delivered when lungs reach
  maturity
• Betamethasone or dexamethasone between 24 34
  weeks gestation to enhance lung maturity
• Tocolysis magnesium sulfate

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Active bleeding

• Stabilize mother hemodynamically
• Deliver by Cesarean section
• Rhogam in Rh-negative mother
• Betamethasone or dexamethasone between 24 34
  weeks gestation to enhance lung maturity

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Management of placenta previa

• No large clinical trials for the recommendations
• Consider hospitalization in third-trimester
• Antepartum fetal surveillance
• Corticosteroid for lung maturity
• Delivery at 36-37 weeks gestation

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Management of placenta accreta

• Cesarean hysterectomy
• Uterine conservation
• Placental removal and oversewing uterine defect
• Localized resection and uterine repair
• Leaving the placenta in situ and treat with
  antibiotics and removing it later

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Placenta Abruption
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What is placental abruption?

• Premature separation of placenta from the uterus

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Epidemiology

• Incident 1 in 86 to 1 in 206 births
• One-third of all antepartum bleeding

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Pathogenesis

• Maternal vascular disruption in decidua basalis
• Acute versus chronic

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Types of placental abruption
16
4
81
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Types of placenta hemorrhage
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Risk factors for placental abruption?

• Maternal hypertension
• Maternal age and parity conflicting data
• Blunt trauma motor vehicle accident and
  maternal battering
• Tobacco smoking and cocaine

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Risk factors for placental abruption

• Prior history of placental abruption
• 5-15 recurrence
• After 2 consecutive abruptions, 25 recurrence
• Sudden decompression of uterus in polyhydramnios
  or multiple gestation (after first twin delivery)
  rare
• Thrombophilia such as factor V Leiden mutation

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Clinical presentations?

• Vaginal bleeding
• Uterine contraction or tetany and pain
• Abdominal pain
• DIC
• 10-20 of placental abruption
• Associated with fetal demise
• Fetal compromise

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Diagnostic test?

• Ultrasound
• Sensitivity 50
• Miss in acute phase because blood could be
  isoechoic compared to placenta
• Hematoma resolution hypoechoic in 1 week and
  sonolucent in 2 weeks
• Blood tests

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Ultrasound subchorionic abruption
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Ultrasound retroplacental abruption
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Ultrasound retroplacental abruption
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Blood tests?

• CBC hemoglobin and platelets
• Fibrinogen
• Normal 450 mg/dL
• lt150 mg/dL severe DIC
• Fibrin degradation products
• PT and PTT

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Management?

• Hemodynamic monitoring
• Urine output with Foley
• BP drop late stage, 2-3 liter of blood loss
• Fetal monitoring

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Management delivery

• Timing
• Severity of placental abruption
• Fetal maturity - consider tocolysis with MgSO4
  and corticosteroid (24-34 weeks)
• Correction of DIC with transfusion of PRBC, FFP,
  platelets to maintain hematocrit gt 25,
  fibrinogen gt150-200 mg/dL, and platelets gt
  60,000/m3
• Mode vaginal vs. Cesarean-section

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Couvelaire uterus?

• Bleeding into myometrium leading to uterine atony
  and hemorrhage
• Treatment
• Most respond to oxytocin and methergine
• Hysterectomy for uncontrolled bleeding

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The End