During pregnancy, an exchange between mother and baby needs to occur in order to deliver essential oxygen and nutrients to the growing fetus. We will discuss what the placenta accreta symptoms and treatments are in this article.
The placenta is the organ that is the interface between the mother’s and the baby’s blood.
It acts as the baby’s lungs, digestive system, and kidneys, and it also supplies vital nutrients and pregnancy hormones until birth occurs.
The placenta must act as this interface without actually invading the mother’s uterine muscle.
When pregnancy occurs, the lining of a woman’s uterus becomes the decidua. One of the functions of the decidua is to prevent the placenta from invading the uterus.
If the decidua is too thin (deficient) it can allow the placenta to embed too deeply. When this happens, it is a placenta accreta.
Read more: What Is A Placenta? 13 Amazing Placenta Facts.
What is placenta accreta?
Normally, the placenta firmly attaches to the uterine wall by little finger-like projections called chorionic villi.
Placenta accreta occurs when the placenta grows abnormally deep into the uterus.
This is a relatively rare but serious condition and is reported to occur in about 1 in 7000 pregnancies.
Normally, after the birth of the baby, high levels of oxytocin in the maternal system trigger the uterus to shrink down, sealing the blood vessels that feed the placenta. As this happens, the placenta easily detaches as it’s pushed off the uterine wall.
In the case of placenta accreta, however, the placenta cannot detach from the uterine wall in the usual way after birth, and the placenta remains attached or partially attached.
Severe bleeding can occur when the maternal blood vessels that are open cannot be shut off.
This can make for a complicated and potentially dangerous delivery of the placenta. It can lead to severe postpartum hemorrhage, often requiring blood transfusion, surgical removal of the placenta, and uterine surgery to correct.
For further information read our article Placenta Accreta | What You Need To Know.
Placenta accreta, increta and percreta. What’s the difference?
The severity of placenta accreta depends on how deeply the chorionic villi have penetrated.
Here are three possible variations:
- Placenta accreta. Chorionic villi attach to the muscle of the uterine wall; this occurs in about 75% of all cases of placenta accreta.
- Placenta increta. Chorionic villi extend into the muscles of the uterus; this occurs in approximately 15% of cases.
- Placenta percreta. Chorionic villi extend through the entire wall of the uterus and often into nearby organs. This is known as placental invasion. Placenta percreta is the deepest form of attachment and occurs in approximately 7% of cases.
Most medical professionals use the term placenta accreta when referring to any of the three variations. The three conditions are also known collectively as the placenta accreta spectrum.
Placenta accreta risk factors
Placenta accreta is thought to occur due to abnormalities in the lining of the uterus, as described above.
However, the biggest risk groups for placenta accreta are women who have had a previous cesarean section, and women with another placental abnormality known as placenta previa.
For more information, please read Placenta Previa | Symptoms And Bleeding.
Placenta accreta vs placenta previa
Placenta previa occurs when the placenta covers, or partially covers the cervix, making vaginal birth impossible.
The placenta grows too low down on the uterine wall, often coming between the baby’s head and the opening of the cervix, ruling out vaginal delivery.
More commonly, a placenta can be described as low-lying, where the edge of the placenta is close to the opening of the cervix, but not touching. Typically, a placenta is described as low lying when the edge of the placenta is two centimeters (20mm) or less away from the cervix.
A low lying placenta is commonly detected around 18-20 weeks during a mid-trimester ultrasound; however, don’t worry too much at this stage if this is the case for you.
More often than not, a low-lying placenta will be pulled up out of the way as the pregnancy progresses and the bottom section of the uterus is formed.
If you’ve been told you have a low-lying placenta, you’ll be offered an additional ultrasound usually around 32-36 weeks to see if it has moved out of the way.
Read more about this in Low Lying Placenta | What Does It Mean?
True placenta previa is linked to previous uterine surgery, most notably C-Section Birth. Therefore, if you’ve had a previous cesarean section, you’re at increased risk of placenta previa.
How common is placenta accreta after c-section?
Previous uterine surgery, including prior cesarean section, increases your chances of placenta accreta spectrum.
If you’ve had one previous cesarean section and you have placenta previa in your current pregnancy, the risk of placenta accreta increases to 25%.
If you’ve had two or more c-sections and currently have placenta previa, the risk of placenta accreta increases to 40%.
Although placenta accreta can occur in the absence of uterine scarring, it’s most likely to happen after a previous c-section. Research has shown between 60-80% of cases of placenta accreta occur in women who had a previous c-section.
Additional risk factors for placenta accreta
Rates of placenta accreta spectrum disorders are becoming more common, due to an increase in a number of clinical risk factors, including rising rates of cesarean section and reproductive technologies, including in vitro fertilization.
Placenta accreta without placenta previa is rare, but there are other risk factors that increase your risk of developing placenta accreta:
- Your placenta attaches over a uterine or C Section Scar. Scar tissues behaves differently from regular healthy tissue; therefore, if your placenta grows over your scar, it can increase the chance of a complicated delivery.
- A previous Dilation And Curettage (D&C), including after an abortion, which involves your uterus lining being scraped. A D&C procedure can cause scar tissue in the upper lining of the uterus, increasing the risk of placenta accreta and placenta previa.
- Advanced maternal age (more than 35 years old)
- Increased number of pregnancies beyond 20 weeks gestational age
- Smoking While Pregnant or using illicit drugs.
- Unexplained elevated maternal serum alpha-fetoprotein (protein found in the blood)
- Uterine fibroids. They take up space in the uterus. Sometimes surgical fibroid removal is necessary but can cause complications during pregnancy. A cesarean delivery might be recommended if you’ve had previous surgery to the uterine wall.
- Asherman’s syndrome. This causes scar tissue or adhesions to form on the wall of the uterus. You can become pregnant but sometimes it can affect fetal development and placental abnormalities. This will increase the likelihood of heavy bleeding, cesarean delivery and the risk of Preterm Birth.
Related reading: Fertility After 40 | What You Need To Know
How serious is placenta accreta?
Placenta previa and placenta accreta are both associated with significant maternal morbidity and mortality, as well as adverse neonatal outcomes.
The biggest concern occurs when diagnosis of placenta accreta happens in labor, as it doesn’t allow for careful planning of care. Therefore, early diagnosis in the antenatal period is key to improve maternal morbidity and the neonatal complications that arise from premature birth.
The major risk of placenta accreta is massive, life-threatening bleeding, because the uterus cannot contract down and shut off the blood vessels that supply the placenta.
More than half of all women with this condition will need blood transfusions if placenta accreta occurs during birth.
If you have been diagnosed with placenta accreta, you will be advised to give birth in a hospital setting, in a labor and delivery unit. It’s important to recognise that, even in the most optimal hospital setting, substantial adverse maternal outcomes still occur.
If the uterus has to be removed during delivery, no future pregnancies will occur.
If complications occur, this can lead to damage to internal organs – including the bowel and bladder – as well as to the uterus. This can lead to dangerously heavy blood loss, blood transfusion, kidney failure and even maternal death.
How early can you diagnose placenta accreta symptoms?
Antenatal diagnosis of placenta accreta is preferable to diagnosis following severe vaginal bleeding in the third trimester, or in The Third Stage Of Labour, following the birth of your baby.
Placenta accreta spectrum can be diagnosed on a routine ultrasound although this can be difficult. In some cases, magnetic resonance imaging (MRI) might also be helpful.
A specialist OBGYN doctor can diagnose a placenta accreta with 95% accuracy using ultrasound imaging.
However, in most cases, placenta accreta is diagnosed based on clinical presentation.
If you have placenta previa, or if you have several risk factors for placenta accreta, you might choose to have screening done.
- Ultrasound. From 15 weeks of pregnancy, ultrasound can identify placenta accreta, although the best results are around 20 weeks, as the ultrasound is more sensitive at this time. The placenta will have a ‘swiss cheese’ appearance if placenta accreta has occurred.
- Blood testing. Raised maternal serum alpha-fetoprotein (AFP) levels, and associated low levels of PAPP-A (a protein produced by the placenta) have been linked to increased rates of placenta accreta. AFP is a protein found in the blood, at highest concentrations in the baby. Due to the decidua being thin, this allows leakage of fetal AFP into the mother’s blood. If these levels are raised with no other obvious cause, placenta accreta is the likely diagnosis.
These methods of blood testing are not a reliable predictor for placenta accreta, however, as levels of both hormones can be abnormal for other reasons.
An exciting new study has found that specialist technology can be used to detect placental cells (trophoblasts) circulating in the mother’s blood stream. Abnormally high levels of these cells in the maternal system, can be indicative of placenta accreta spectrum. This screening could be performed in pregnant women as early as the first trimester.
Early diagnosis of suspected placenta accreta can mean earlier referral to specialist doctors and specialized care.
Related reading: Pregnancy Week By Week – The First Trimester
Placenta accreta symptoms
If you have risk factors for placenta accreta, it’s likely your doctor will make sure you have a thorough ultrasound to check for the placenta’s position – especially if you’ve had a previous c-section.
The most common presentation of a placental problem during pregnancy is heavy vaginal bleeding that occurs in the second or third trimester.
However, not everyone with a diagnosis of placenta accreta will have vaginal bleeding.
Sometimes the first sign of placenta accreta occurs during birth.
Learn more in our article Bleeding During Pregnancy | 7 Causes Of Vaginal Bleeding
Placenta accreta treatment
If diagnosis does occur during birth, there are three treatment options available:
- An emergency cesarean hysterectomy (the most likely outcome)
- Very rarely would the placenta be forcibly removed, as this increases the risk of massive blood loss and subsequent hysterectomy
- Conservative management, which leaves the placenta in place. Drugs are used to contract the uterus and prevent infection, as well as the blocking of certain arteries to minimize bleeding. The placenta is reabsorbed by the body; studies have shown this to be successful in about 80% of cases. It’s considered a very controversial option due to the risk of bleeding and infection.
If placenta accreta is diagnosed before the birth, then management can be carefully planned. The usual outcome is an elective c-section at around 38 weeks of pregnancy.
The risk of complications from placenta accreta is reduced if the surgery is planned rather than performed in an emergency.
In some cases of placenta percreta, where the placenta might be deeply adhered to the muscle and wall of the uterus – as well as to other organs such as the bladder – it might be necessary to involve other specialists, such as trauma surgeons, urologists, and/or general surgeons.
Collaborative teamwork requires careful planning and is much more likely to be successful if performed in an elective procedure, rather than as emergency surgery.
At the time of the c-section, the uterus will be surgically removed (hysterectomy), to prevent hemorrhage. Counseling and planning are important aspects of a diagnosis of placenta accreta during pregnancy.
How do you prevent placenta accreta?
Placenta accreta cannot be prevented.
Although women are also experiencing higher numbers of other risk factors – such as increased maternal age and a greater likelihood of having uterine procedures for fibroids – the ever increasing rate of c-sections is having an impact.
Avoiding c-section in the first instance would increase your chances of avoiding this serious, life-threatening complication in future pregnancies.
If you have had previous cesarean sections or uterine surgery, speak to your doctor about the risks of placenta accreta, placenta increta and placenta percreta.
Related reading: US Women Have Too Many C-Sections, With Too Many Risks.