Placenta Praevia Flashcards
What are the causes of antepartum haemorrhage?
The three causes of antepartum haemorrhage to remember are placenta praevia, placental abruption and vasa praevia. These are serious causes with high morbidity and mortality.
Causes of spotting or minor bleeding in pregnancy include cervical ectropion, infection and vaginal abrasions from intercourse or procedures.
What is placenta praevia?
Placenta praevia is where the placenta is attached in the lower portion of the uterus, lower than the presenting part of the fetus. Praevia directly translates from Latin as “going before”.
Briefly differentiate between a low-lying placenta and placenta praevia
The RCOG guidelines (2018) recommend the following definitions:
- Low-lying placenta is used when the placenta is within 20mm of the internal cervical os
- Placenta praevia is used only when the placenta is over the internal cervical os
How common is placenta praevia?
Placenta praevia occurs in around 1% of pregnancies. It is a notable cause of antepartum haemorrhage.
What risks are associated with placenta praevia?
Placenta praevia is associated with increased morbidity and mortality for the mother and fetus. The risks include:
- Antepartum haemorrhage
- Emergency caesarean section
- Emergency hysterectomy
- Maternal anaemia and transfusions
- Preterm birth and low birth weight
- Stillbirth
What are the risk factors for placenta praevia?
The risk factors for placenta praevia are:
- Previous caesarean sections
- Previous placenta praevia
- Older maternal age
- Maternal smoking
- Structural uterine abnormalities (e.g. fibroids)
- Assisted reproduction (e.g. IVF)
How does placenta praevia present?
The 20-week anomaly scan is used to assess the position of the placenta and diagnose placenta praevia.
Many women with placenta praevia are asymptomatic. It may present with painless vaginal bleeding in pregnancy (antepartum haemorrhage). Bleeding usually occurs later in pregnancy (around or after 36 weeks).
For women with a low-lying placenta or placenta praevia diagnosed early in pregnancy (e.g. at the 20-week anomaly scan), when does the RCOG guideline (2018) recommends a repeat transvaginal ultrasound scans?
For women with a low-lying placenta or placenta praevia diagnosed early in pregnancy (e.g. at the 20-week anomaly scan), the RCOG guideline (2018) recommends a repeat transvaginal ultrasound scan at:
- 32 weeks gestation
- 36 weeks gestation (if present on the 32-week scan, to guide decisions about delivery)
When are corticosteorids given to the mother given the risk of preterm delivery?
Corticosteroids are given between 34 and 35 + 6 weeks gestation to mature the fetal lungs, given the risk of preterm delivery.
How does placenta praevia impact the delivery of the baby?
Planned delivery is considered between 36 and 37 weeks gestation. It is planned early to reduce the risk of spontaneous labour and bleeding. Planned cesarean section is required with placenta praevia and low-lying placenta (<20mm from the internal os).
Depending on the position of the placenta and fetus, different incisions may be made in the skin and uterus, for example, vertical incisions. Ultrasound may be around the time of the procedure to locate the placenta.
Emergency caesarean section may be required with premature labour or antenatal bleeding.
What is the main complication of placenta praevia?
The main complication of placenta praevia is haemorrhage before, during and after delivery.
How is haemorrhage of placenta praevia managed?
The main complication of placenta praevia is haemorrhage before, during and after delivery. When this occurs, urgent management is required and may involve:
- Emergency caesarean section
- Blood transfusions
- Intrauterine balloon tamponade
- Uterine artery occlusion
- Emergency hysterectomy
