What is placenta praevia?
Placenta praevia means placenta first. In a normal pregnancy the placenta is in the upper part of your uterus. With placenta praevia, however, the placenta is in the lower part of your uterus, often between your baby and your cervix (the neck of the uterus).
During the last 3 months of pregnancy, the lower part of your uterus becomes thinner and stretches around the growing baby. This can cause a low placenta to tear or pull away from the uterus. This results in bleeding (your blood, not the baby’s).
How common and how serious is placenta praevia?
Early in pregnancy a low lying placenta is common, but later in pregnancy placenta praevia occurs in about 1 in every 200 pregnancies, although it is less common in first pregnancies.There are different degrees of the condition:
- Grade 1 (minor) is when the placenta is mainly in the upper part of the uterus, but some of it extends into the lower part – the most common type.
- Grade 2 (marginal) is when the placenta reaches the cervix, but doesn’t cover it.
- Grade 3 (major) is when the placenta partially covers the cervix.
- Grade 4 (major) is when the placenta completely covers the cervix. This is the most serious type of placenta praevia.
What causes placenta praevia?
Placenta praevia happens when the fertilised egg implants in the lower part of your uterus (womb). The placenta may develop lower than it should because:- There is a large area of placenta (if you are carrying twins, for example)
- You may have scarring on the lining of your uterus, caused by a previous Caesarean or curettage
- Often there is no obvious cause.
How will you know if you have placenta praevia?
Placenta praevia is usually picked up on ultrasound. Most pregnant women have an ultrasound scan between 18 and 20 weeks, and if this shows a low-lying placenta, another scan will be performed at about 32 weeks to see if the placenta is still low. Only 2 – 5% of women who had a low-lying placenta on their first scan will have placenta praevia that is severe enough to need Caesarean delivery.If you have any bleeding during pregnancy, you will probably have an ultrasound scan to find out if you have placenta praevia. Bleeding doesn’t always mean you have placenta praevia. Bleeding can be caused by a bleed behind a normally positioned placenta, the bleeding may be coming from your cervix, or there may be no obvious cause at all for the bleeding.
What happens if you have placenta praevia?
If you have placenta praevia you will probably bleed at some stage of your pregnancy. This usually happens after 28 weeks when the lower part of your uterus is thinner and stretched. The bleeding may be small or large in amount, and is usually painless. However, even a small amount of bleeding needs to be checked out by your doctor.There is nothing that can be done to change the position of your placenta, so placenta praevia is managed by trying to reduce your chance of bleeding. The aim of this is to allow your baby to grow to a size and age that will give your baby the best chance of survival.
If you have a minor grade of placenta praevia, and the bleeding has stopped, you may be able to go home. However, you will need to be close to the hospital, and have access to immediate transport. You will also need to avoid sex.
If yours is a more serious case, you may have to stay in hospital until delivery because of the risk of heavy bleeding.
What happens in hospital?
If you have had a large bleed- You may need an intravenous drip.
- Your baby’s heartbeat will be listened to regularly.
- You will have blood taken to check your haemoglobin and blood group. Donor blood will be kept available in case you continue to bleed and need a transfusion. You will have blood taken each week so that an exact match is always ready.
- If you have Rh negative blood group you will be given an anti-D injection (have a look at the topic 'Routine antenatal tests' for more information about Rh negative blood group and anti-D injections).
- If your blood test shows that you are anaemic, your doctor may prescribe iron tablets.
Just because you are in hospital doesn’t mean you need to stay in bed. Once the bleeding has settled you will be able to wander around the hospital and grounds as long as you tell the staff where you are going.
Being in hospital will not prevent you from bleeding. It means that if you have a large bleed your baby can be delivered as quickly and safely as possible.
Is a Caesarean always necessary?
Most women with Placenta Praevia will have a Caesarean section. Contractions may cause heavy bleeding as the placenta separates from your uterus. The placenta also prevents your baby’s head from becoming engaged in your pelvis.If you have a grade 1 or 2 Placenta Praevia, a vaginal delivery may sometimes be possible. However, with grades 3 and 4, a Caesarean section is necessary. The Caesarean section will be planned for a time when the baby is mature, usually at about 38 weeks, hopefully before you go into labour.
If you have a Caesarean section an anaesthetist will talk with you about the best anaesthetic to have – you may need a general anaesthetic.
Is placenta praevia dangerous?
Placenta praevia is potentially life threatening. You may not bleed at all during your pregnancy, but it is possible for you to have a large haemorrhage at any time. You could lose your entire volume of blood in 10 minutes. This is why you need to stay in hospital close to emergency facilities.Your doctor or midwife can provide you with more information about placenta praevia. Please talk to them if there is anything that you don't understand about your condition, or if you have any concerns.
source: http://www.cyh.com/HealthTopics/HealthTopicDetails.aspx?p=438&np=462&id=2785
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