Placenta praevia

Question 1

Definition of placenta praevia

Answer 1

• Placenta implanted into the lower segment of the uterus

Question 2

Classification of placenta praevia

Answer 2

• Major
  
  • Complete or partial obstruction of the cervical os
• Minor
  
  • Placenta located in the lower segment of the uterus, but does not obstruct the cervical os
    
    • Marginal (within 2 cm of cervical os)
    • Low-lying (2-3.5 cm)

Question 3

Definition of vasa praevia

Answer 3

• Foetal vessels overlie the cervical os
• Typically occurs with velamentous cord insertion
  
  • Umbilical cord inserts and travels within the foetal (chorioamniotic) membranes to the placenta
• Rupture is likely to result in foetal mortality
• Diagnosis is suspected when spontaneous or artificial rupture of the membranes is accompanied by painless, fresh vaginal bleeding → Emergency Caesarean

Question 4

Definition of placenta:

• accreta
• increta
• percreta

Answer 4

• Placenta accreta
  
  • Abnormally adherent to uterine wall
• Placenta increta
  
  • Invasion of the myometrium
• Placenta percreta
  
  • Invasion through the myometrium (sometimes into adjoining tissues)

Question 5

Risk factors for placenta praevia

Answer 5

• Previous Caesarean
• Advanced maternal age
• Multiple pregnancy
• Multiparity
• Assisted conception
• Smoking

Question 6

Complications of placenta praevia

Answer 6

• Placental abruption
  
  • APH
  • PPH
• ↑ likelihood of Caesarean section
• ↑ likelihood of hysterectomy (accreta/increta/percreta)

Question 7

Clinical features of placenta praevia

Answer 7

Symptoms

• Red, profuse, painless vaginal bleeding
  
  • * Digital vaginal examination should NEVER be performed on women with active vaginal bleeding until the position of the placenta is known with certainty *

Signs

• Foetal head high, not engaged
• Breech presentation
• Transverse lie
• Caesarean scar

Question 8

Investigations for placenta praevia

Answer 8

• Ultrasound (at 20 weeks)
  
  • Transabdominal
  • Transvaginal
    
    • Superior, but ↑ risk of abruption
    • Doppler/MRI can be performed to diagnose vasa praevia and placenta accreta

Repeat ultrasound at 32 weeks if major, 36 weeks if minor

• The majority of low-lying placentas will migrate during pregnancy and resolve spontaneously

Question 9

Management of placenta praevia

Answer 9

• Minor → possible vaginal delivery
• Major → Caesarean section
  
  • Elective - 38 weeks
• Rhesus incompatability
  
  • Anti-D immunoglobulin (28 weeks)
• Corticosteroids (if gestation <34 weeks)
  
  • Promote foetal lung maturity
• Haemorrhage
  
  • Monitor haemodynamic stability
  • Resuscitation
    
    • Crystalloids
    • Blood & blood products

Consider hospital admission for women who experience APH until delivery