Early diagnosis and specialised care will help to reduce harms associated with complications of the placenta such as placenta praevia and placenta accreta and ensure the safest possible outcome for mother and baby, concludes latest guidance from the Royal College of Obstetricians and Gynaecologists (RCOG).
Both placenta praevia and placenta accreta are associated with high maternal and neonatal morbidity and mortality. The highest rates of complication for both mother and newborn occur when these conditions are only diagnosed at delivery, highlighting the need for prenatal diagnosis, say the guidelines.
The rates of placenta praevia and accreta have increased and are likely to continue to increase as a result of rising rates of caesarean births and use of assisted reproductive technology, such as IVF.
The risks of both conditions, which are often combined, increases with the numbers of previous caesarean sections. The latest guidelines recommend that women must be informed of this risk when discussing the benefits and risks of a caesarean birth.
Placenta praevia refers to a low lying-placenta. It occurs when the placenta attaches in the lower part of the womb and can sometimes completely cover the neck of the womb. The condition can lead to heavy bleeding during pregnancy or birth.
It is checked for during the routine 20-week ultrasound scan. If it is detected, a woman will have the opportunity to discuss her birthing options with her healthcare professional. A caesarean is usually the safest way to give birth, but this will depend on her individual circumstances.
Placenta accreta is a rarer condition. It occurs in between 1 in 300 and 1 in 2000 pregnancies, depending on the number of prior caesarean sections. Placenta accreta is when it sticks abnormally to, or invades deeply, the muscle of the womb including nearby structures like the bladder.
When unknown at the time of birth, it usually causes heavy bleeding and sometimes a massive haemorrhage which may require an emergency hysterectomy and intensive care admission for either mother or baby, or both. It may be suspected during routine ultrasound scans during pregnancy.
When a placenta accreta is diagnosed before birth, a specialist obstetrician will discuss all the birthing options and the extra care that will be needed. It may be planned for a woman to give birth early, between 35 and 37 weeks of pregnancy, depending on a woman’s individual circumstances.
Revised guidance on vasa praevia, a rare condition affecting between 1 in 1200 and 1 in 5000 pregnancies, has also been published. In vasa praevia, blood vessels from the baby to the placenta, unprotected by placental tissue or the umbilical cord, pass near to the cervix and can tear during labour or when a woman’s waters break. This is very dangerous as the blood lost comes from the baby.
Risk factors for vasa praevia include a low-lying placenta, a multiple pregnancy or if the placenta or umbilical cord develops in an unusual way. It may be possible to diagnose with ultrasound imaging at the routine 20-week scan. If vasa praevia is confirmed during pregnancy, a woman should be offered a planned caesarean at around 34-36 weeks. If suspected during labour or when a woman’s waters break, an emergency caesarean is usually recommended.
Professor Eric Jauniaux, lead author of the guidelines and Consultant Obstetrician and Senior Lecturer at University College London, says:
“We hope this updated guidance will support healthcare professionals during discussions with women and their partners who may be considering assisted reproduction, particularly IVF, or an elective caesarean birth. Guidelines should also help clinicians diagnose these potential complications early, and to discuss with women the safest possible ways to give birth and the advantages and disadvantages associated with each approach to ensure the best possible outcomes and to ensure personalised care.”
Dr Geeta Kumar, Chair of the RCOG Patient Information Committee said:
“It is important for women to be aware of these complications of the placenta, but they should be reassured that these are very rare and specialist care is available. Early diagnosis is key to reduce harms associated with placenta praevia and accreta to ensure the safest possible outcome for mother and baby.”