What is placenta praevia, and what are its symptoms and risk factors? Balanced information on placenta accreta, vasa praevia, monitoring and birth plans.
Placenta praevia is when the placenta sits in the lower part of the womb and partly or completely covers the cervix; it is usually noticed at the routine ultrasound scan in the middle of pregnancy. In most cases the placenta moves upwards as the pregnancy advances and no problem remains; if it continues, it is monitored with extra ultrasounds and the birth plan is made accordingly.
What is placenta praevia (a low-lying placenta)?
Placenta praevia is when the placenta sits in the lower part of the womb and partly or completely covers the cervix. If the placenta is very close to the cervix but does not completely cover it, this is called a "low-lying placenta".
How does it differ from placenta accreta and vasa praevia?
Placenta accreta is the placenta attaching tightly to the womb muscle or to nearby structures such as the bladder; it is rare and can cause serious bleeding at birth. Vasa praevia is when the baby's blood vessels pass near the cervix without being protected by placental tissue or the umbilical cord; it is very rare, but if these vessels tear it poses a very serious danger to the baby.
What is placental abruption (abruptio placentae)?
The placenta can separate from the wall of the womb before birth; this is called placental abruption, and it is a different condition from placenta praevia. It is usually accompanied by constant pain; the bleeding can collect inside the womb and stay hidden, so the amount of visible bleeding does not always reflect how serious the condition is.
What are its symptoms?
Bleeding due to placenta praevia is usually painless, bright red and can also appear after sex. Bleeding due to placental abruption is usually accompanied by constant pain and a feeling of tightness or tension in the womb; even if the bleeding looks small, the condition can be serious. The baby lying in a breech or transverse position can raise suspicion of praevia. Do not try to tell which situation you are in yourself.
What are the risk factors?
Previous caesarean births, IVF or similar fertility treatments and smoking are among the risk factors for placenta praevia. Previous caesarean and womb operations, fibroids or a bicornuate womb structure, older age and IVF treatment are counted among the risk factors for accreta; a low-lying placenta, multiple pregnancy and unusual development of the cord are counted among the risk factors for vasa praevia. Having these factors does not mean praevia, accreta or vasa praevia will develop; it is nobody's fault.
How is it diagnosed and monitored?
A low-lying placenta is usually noticed at the routine ultrasound scan in the middle of pregnancy. A transvaginal ultrasound, which is a safe method, is used to confirm it. If the placenta is found to be low-lying, it is monitored with extra ultrasound scans; in most cases the placenta moves upwards as the pregnancy advances, and in those that continue, monitoring goes on.
How is birth planned?
The mode and timing of birth are planned together with you according to how far the placenta is from the cervix and other risks. If the edge of the placenta is very close to the cervix, a caesarean can be the safest method; if it is further away, vaginal birth can be chosen. If there has been no bleeding, birth is planned for a particular time; if there has been bleeding in pregnancy, birth may be needed earlier. For a caesarean it is recommended that a senior team is present and preparation is made for the possibility of a blood transfusion; if bleeding cannot be brought under control, a hysterectomy may be needed. If you do not accept blood transfusion, it is important to tell your team early. In cases where accreta is detected, birth is generally planned at a centre experienced in this; if vasa praevia is detected, a planned caesarean is recommended.
What can it mean for the mother and baby?
These conditions can raise likelihoods such as the risk of bleeding, preterm birth and, rarely, the need for a hysterectomy or a blood transfusion. In vasa praevia, if the vessels are damaged this poses a very serious danger to the baby. Even so, with regular monitoring most pregnancies end healthily.
How can you support yourself?
- If it is known that you have a low-lying placenta, seek care straight away for any bleeding, contractions or pain.
- Do not miss your check-ups and the tests recommended.
- Have the tests recommended for checking anaemia.
- Tell your team early about your preference on blood transfusion.
- Consult your doctor about sex and heavy activity.
- Share your worries; ask for support if needed.
What can you ask your doctor?
- How does the position of my placenta affect my mode of birth?
- In what situation are an extra ultrasound or check-up needed?
- What should I do if there is bleeding or contractions?
- How is preparation made if a caesarean is needed?
- How can I tell the team my preference on blood transfusion?
Frequently Asked Questions
What check-ups are done during monitoring?
When a low-lying placenta is detected, monitoring continues with more than one extra ultrasound; the length of the cervix can also be measured if needed. Because the position of the placenta is reassessed at every check-up, the birth plan is set according to the latest findings.
If I have placenta praevia, will I definitely have a caesarean?
No. The decision is made according to how far the placenta is from the cervix. If the placenta is far enough from the cervix, vaginal birth can also be an option; the decision is made specifically for you.
Why should painless bleeding be taken seriously?
Because bleeding due to placenta praevia can be overlooked precisely because it is usually painless. Even if the amount looks small, for any bleeding you need to go to a health facility straight away.
Is placental abruption the same as praevia?
No. Both can cause bleeding, but they are different conditions. In placental abruption constant pain is usually typical and the bleeding can stay hidden.
What happens if vasa praevia is not detected beforehand?
If vasa praevia is not detected during pregnancy, noticing it once labour has begun or the membranes have opened may need an emergency caesarean. For this reason, detecting it during pregnancy is important so that the birth can be planned beforehand.
Do placenta praevia and a low-lying placenta describe the same position?
No. In praevia the placenta partly or completely covers the cervix. A low-lying placenta is very close to the cervix but does not completely cover it.
Does finding a low placenta mean its position will always stay the same?
No. In most cases the position shifts upwards as pregnancy advances. Those that continue are monitored with extra ultrasounds.
Does the bleeding looking small show that the condition is mild?
No. Especially in placental abruption, the bleeding can stay hidden inside the womb. The amount seen does not always reflect how serious it is; do not try to tell the situation apart yourself.
If I have a low-lying placenta, should I wait if there is pain or contractions?
No. You should seek care straight away for any bleeding, contractions or pain.
Does a previous caesarean mean a placental problem will definitely develop?
No. A previous caesarean is among the risk factors, but it does not mean these problems will develop. Such a situation is nobody's fault.
Should I tell my team beforehand about my preference on blood transfusion?
Yes. If you do not accept blood transfusion, tell your team in the early period. This preference should also be covered when preparation for the birth is discussed.
If vasa praevia is detected, is the birth planned beforehand?
Yes. When vasa praevia is detected, a planned caesarean is recommended. In cases where placenta accreta is detected, birth is generally planned at an experienced centre.
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