Complications And Risks of Placenta Previa During Pregnancy

Complications And Risks of Placenta Previa During Pregnancy

Placenta Previa: Complications And Risks All You Need To Know

What is a placenta?

A placenta is a temporary organ in the uterus that develops during the 20th week of gestation and continues to grow throughout the pregnancy. It attaches the growing fetus to the mother via a rope-like structure called the umbilical cord to provide all the nutrients and oxygen from the mother to the baby and transfers the waste from the baby to the mother which is excreted out from her blood circulation. It also produces the hormone called progesterone, which helps in the maintaining the pregnancy till term.

What is placenta Previa?

Many complications develop during the time of pregnancy and many of them include the placenta. One of the complications that arises is placenta Previa. Normally, the placenta is attached to the upper segment of the uterus, most commonly to the fundus of the uterus, which is the most muscular region in the uterus. But in a placenta Previa, it attaches to the lower segment of the uterus, which the least muscular region of the uterus.
This is the reason why it can cause multiple and ominous health concerns in a pregnant woman. This phenomenon occurs in at least 1 pregnancy in every 200 live births in the third trimester. The low lying placenta obstructs the opening of the cervix, which means it may become risky for a mother to opt for a normal vaginal delivery.

Bleeding in placenta previa

The primary reason why bleeding occurs in placenta previa is because of the site of the attachment of the placenta. The more low lying the placenta is, the greater the chances of bleeding more as the placenta attaches to the least muscular part of the uterus.

 

What are the complications And Risks of Placenta Previa?

Many complications are associated with placenta Previa and many of them are serious concerns
• There maybe restricted fetal growth and the fetus can also present in an abnormal or breech position
• Hemorrhaging in the mother
• Fetal distress due to reduced blood supply
• The chances of preterm delivery are markedly increased
• If the placenta does not detach from the uterus, then a hysterectomy would be done. In this procedure, the entire uterus is removed.
• A premature delivery means premature baby, which can lead to health risks
• Placenta Previa can lead to placenta accreta where the placenta grows too deep in the uterus tissues
Vasa-Previa-Risks-in-pregnancy

What are the causes  And Risks of Placenta Previa?

Various reasons may result in the development of placenta previa, such as if:
• A woman underwent a cesarean section in her previous pregnancy
• A woman is carrying more than one fetus, maybe twins or more
• A woman had surgical marks from her previous surgeries of uterus
• A mother  smokes cigarette
• The mother is older in age
• Fibroids are present in the uterus
• Structural abnormalities of the uterus
• Lower segment attachment of the fertilized egg

Placenta-Previa-risks

What Are The Types Of Placenta Previa?

Every placenta Previa can form differently. There are 4 types of presentations in the uterus.
• Type 1: the placenta lies in the lower segment of the uterus but does not cover the internal is of the cervix. This type is usually not a risky case, and a normal vaginal delivery is possible with extra care.
• Type 2: the placenta is in the lower segment, slightly covering the internal os but not completely. A normal vaginal delivery is also possible in this case.
• Type 3: one edge of the placenta partially covers the internal os. In this case, many women would be advised to go for a cesarean delivery, but if the placenta has migrated upward to the upper segment during the advanced stages of the pregnancy, then a normal vaginal delivery may be possible.
• Type 4: the low lying placenta completely covers the internal os, leaving no space for the baby to be delivered via vaginal canal. This type of placenta Previa is the most dangerous type, as it can lead to massive hemorrhage and is regarded as a risky pregnancy. This type can also lead to placental abduction.

What Are The Symptoms Of Placenta Previa?

The presentation of placenta Previa is not unique. Any complication after 20 weeks of pregnancy can present with vaginal bleeding and a woman with placenta Previa would present with:
• vaginal bleeding and no abdominal pain, most commonly in the third trimester.
The bleeding depends on how much the placenta is covering the internal os. If it partially covers the internal os, the bleeding may be mild but if the placenta covers the internal os completely, the bleeding would be heavy and it could also lead to a hemorrhage. In such cases, the life of the mother is at risk with lower chances of fetal compromise. Though, other risks can develop with the fetus, such as:
• The fetus may not grow in correspondence to its gestational age
• The fetus may be born with birth defects
• There is a risk of premature delivery

What Is The Treatment For Placenta Previa?

When you go to a doctor with unusual symptoms and bleeding, the first thing your doctor would do is to perform an ultrasound on you. This test will tell what exactly is happening inside the uterus, and if your placenta is lying low, this ultrasound will also detect this finding. If your doctor is suspecting a placenta Previa, they would not perform a digital vaginal examination on you.
The treatment of placenta Previa depends on:
• How severe your bleeding is
• How is the mother’s health and condition
• The gestational age of the baby
• Position of the baby
• Location of the placenta
• Health and maturation of the baby
The management is mostly supportive; if you are bleeding, your doctor would transfuse blood and intravenous fluids in you to replenish the volume you lost. You would be given tocolytic drugs to reduce the contractions of the uterus, along with corticosteroids which helps in the maturation of the fetal lungs. If the bleeding has stopped you will be sent back home. Your doctor will advise you to take complete bed rest with limited movements, but if the bleeding is too heavy to be controlled, the last resort would be to deliver the baby and the placenta via a cesarean section. But once the placenta has taken its position it can not be moved, unless it migrates itself during the course of pregnancy, and there is no treatment for the placenta Previa.

How to prevent placenta Previa?

Placenta Previa is simply the placental attachment away from its normal attachment and there is really no way of preventing it from happening. What you can do is to minimize its symptoms and take care of yourself.
• If you smoke, you should stop smoking
• If there is a risk of massive bleeding, you need to take complete bed rest
• You need to avoid doing chores or exercises
• Avoid travelling in this condition
• Avoid having intercourse

Dangerous Placenta Previa

The prognosis of placenta Previa is good. All the symptoms are manageable if the situation is taken care of professionally. Most women end up delivering via a cesarean section at the end of their term or in emergencies if a woman is bleeding massively.

Placenta Previa at 20th week:

A woman who may have placenta previa presents with painless vaginal bleeding as early in the 12th week of gestation as this is the time the placenta is completely produced. But instead of attaching to its typical site in the uterus which is the fundus of the uterus, the placenta attaches to another site, that can be the lower part or sides of the uterus.

Placenta previa is detected in at least one pregnant woman out of every four pregnant women before the 20th week of gestation. But not all women with placenta previa by 20th week continue to have a placenta in the wrong position till the last trimester. Even if the placenta attaches to the wrong site, it migrates to its normal position as the time passes. When this happens, it is no more a placenta previa.

But at least one woman out of 200 pregnant women continues to have a placenta that remains attached in the abnormal site till the third trimester. If this occurs, then labor in such pregnant women becomes very dangerous and can also be fatal.

It is especially true if the placenta completely covers the internal os, which is the natural passage for the baby to come out from, this condition is regarded as complete placenta previa. If it bleeds, then there may be massive blood loss, and if there are large vessels crossing over the placenta, then the blood loss will be much greater and can send the mother into hypovolemic shock rapidly.

Placenta Previa Ultrasound:

To check for placenta previa on ultrasound, it is a must that the placenta has completely developed so it can be seen on the imaging. For this reason, a radiological diagnostic test should be performed after 20 weeks of gestation.

Placenta previa is usually detected on an ultrasound or magnetic resonance imaging (MRI). Placenta previa is usually detected on routine radiological tests. On an ultrasound, the doctor calculates the distance between the edge of the placenta and the internal os. If the distance is significant enough, then the placenta must be in its correct position, and it will not be placenta previa.

But if the distance between the lower edge of the placenta and the internal os is reduced to a dangerous point, then it is suspected as placenta previa. Still, in such cases, an ultrasound should be repeated at 32 weeks of gestation to know if the placenta is still in the abnormal position or it has migrated to its normal position.

To perform an ultrasound, it is advisable to go for a transvaginal ultrasound, which will produce more accurate results than the transabdominal ultrasound. It is because transabdominal ultrasound may sometime incorrectly diagnose placenta previa.

On the other hand, placenta previa is also detected in an MRI. It is the gold standard imaging to look for placenta previa, but in most cases, an MRI is not needed, and ultrasound is enough to make a diagnosis of placenta previa. On the MRI, the distance between the internal os and the lower edge of the placenta is better appreciated.

Placenta Previa And Birth Defects:

Studies have shown that placenta previa is associated with an increased risk of congenital birth defects in single births, and the risk is increased by 1.6 folds.

Other than this, in high-risk placenta previa patients, the most appropriate mode of delivery in such is c section. And because c section is performed before the term ends, for instance, at 33 to 34 weeks of gestations, there are high chances that the baby is born with complications related to premature delivery.

Such complications may include underdeveloped lungs of the fetus, which may result in breathing problems. The fetus may even turn hypoxic due to a lack of oxygen. Similarly, the newborn may have low birth weight, cerebral palsy as a result of birth injury, and hypoxic-ischemic encephalopathy (HIE).

Placenta Previa Management:

The management of a patient with placenta previa requires prompt handling as the patient’s health is rapidly deteriorating. The nurses are required to assess the overall condition of the patient.

  • The first thing is to check the patient’s vital and other baselines. It is crucial to keep the patient under constant surveillance and check her blood pressure as often as every 5 to 10 minutes.

 

  • At the same time, it is necessary to check the fetus’ condition, as well. The nurse should monitor the heartbeat of the fetus as well as the movements of the unborn to make sure that the well being of the unborn baby is intact.

 

  • The next important thing is to monitor the contractions of the uterus of the mother to check if she in labor. The constant monitoring will help in predicting when the labor will be induced.

 

  • The nurses will assess the general examination of the patient to see if her health is progressing or deteriorating. It is imperative to examine the patient in the left lying position to take off the pressure of the weight of the uterus from her organs and abdominal artery.

 

  • In case a woman is bleeding, it is vital for the overall health of the patient for the nurses to know how much blood is lost. The amount of blood loss will also help calculate how much fluid should be replaced in the patient. If the blood loss is massive, then the patient may even require a blood transfusion. To know the amount of blood lost, the nurses will have to check how many perineal pads are saturated in every hour.

Differential Diagnosis:

There are other conditions that may be similar to placenta previa in terms of signs or symptoms. It may include:

  • A bladder that is full
  • Focal myometrial contraction

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References:

Medical News Today

Webmd

 

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