Placenta Previa

What are the risk factors for placenta previa?

- Damage to endometrium (c-section, uterine surgery, abortion, multiparity) - Multiple placenta - Large placenta - >35 years - Smoking - Fibroids

When is the placenta's position determined?

20 week scan

How is placenta previa graded?

By how much it covers the internal cervical os - Complete - Partial - Marginal (within 2cm of cervical Os)

How is placenta previa treated?

Corticosteroids - enhance foetal lung maturity Minor bleeding - bed rest Major bleeding - blood products + IV fluids Severe impact on mother/child - emergency c-section

What are the complications of placenta previa?

Foetal hypoxia Preterm delivery Haemodynamic shock (mother)

How does the placenta usually implant?

In the upper uterine segment

What causes placenta previa?

No known cause, but hypothesised: when endometrium is not well vascularised because all the risk factors (previous c-section, abortion, multiparity etc) all reduce vascularity

How common is placenta previa?

Only 10% of those with low-lying placenta's go on to have placenta previa at term! (Usually corrects itself as the uterus grows)

How does placenta previa present?

Painless bright red bleeding after 20 weeks gestation (because as the LUS grows it disrupts the placental blood vessels!)

What is placenta previa associated to?

Placenta accreta

What is the definition of placenta previa?

Placenta first

What is placenta previa?

Placenta is the first thing in the uterine cavity - implants in the lower uterine segment and covers internal Os

How is placenta previa diagnosed?

Prenatal USS During labour (bleeding!)