What is Placenta previa?

Placenta previa is a complication of pregnancy that characteristically presents with non-painful vaginal bleeding during the third trimester due to the abnormal location of the placenta at the cervix. The placenta is an organ that develops only during pregnancy. Its role is to provide the foetus with oxygen and nutrients required for the baby’s growth. Its function is also to remove waste products from the baby’s blood via the umbilical cord. It normally attaches to the wall of the uterus. The cervix is the structure found at the bottom of the uterus which widens during labour and delivery to create the passage through which the baby will come out.

When the placenta is attached on top of the opening (cervix), this condition is known as placenta previa. It can partially or totally cover the cervix. This condition can result in severe bleeding that can even lead to death. Placenta previa occurs in around 0.5% of all pregnancies in the United States. The risk of having this condition increases by 1.5 to 5 times if you have a history of caesarean delivery. No studies have shown any racial predilection for the condition. However, it has been observed to be more common among women with advanced maternal age (35 and above).

What are the causes of placenta previa?

The implantation of the placenta usually begins when the embryo adheres to the wall of the uterus. During the process of placental development, it may unfortunately develop to cover the cervix. Bleeding due to placenta previa is usually initiated when the lower part of the uterus is changing in preparation for labour during the third trimester of pregnancy. This causes a gradual detachment of the placenta from the uterus. The placenta, being an organ rich in blood vessels, starts to bleed. The exact cause of placenta previa is unknown.

What are the risk factors for placenta previa?

The following factors may increase your risk of having placenta previa:

• Advanced maternal age
• History of infertility treatment
• Having had many children
• Having multiple gestation (for example twins or triplets)
• Short time interval in between consecutive pregnancies
• History of uterine surgery
• History of caesarean delivery
• History of previous abortions
• History of placenta previa
• Low socioeconomic status
• Smoking
• Cocaine use

What are the signs and symptoms of placenta previa?

Placenta previa classically presents with painless bright red bleeding from the vagina which can stop spontaneously and restart with labour. The symptoms most likely occur during the third trimester of pregnancy. Other signs and symptoms include the following:

• Profuse bleeding
• Decrease in blood pressure
• Increased heart rate

How is the diagnosis of placenta previa made?

To make the diagnosis of placenta previa, your doctor will start by asking you a series of questions to know more about your symptoms. He/she will then proceed with a physical examination to look for signs of placenta previa. The diagnosis of placenta previa is usually confirmed by an ultrasound scan. It can be diagnosed as early as in the second trimester during a routine placental appointment as well. Ultrasound scan is performed using a special device which emits sound waves. These sound waves are then interpreted on a monitor where the inside of the uterus can be visualized. It is a non-invasive test that does not involve any radiation.

Ultrasound scan can be done in 2 ways in pregnant women. The first type of ultrasound is known as the transabdominal ultrasound. In this technique, an ultrasound gel is applied on your pregnant belly and the probe is placed on the gel to form the images. The second type of ultrasound is the transvaginal ultrasound. In this method, a wand like probe is inserted inside the vagina. It is considered as the best ultrasound technique to make the diagnosis of placenta previa.

How is placenta previa managed?

Placenta previa cannot be prevented. There are also no medical or surgical treatment to cure the condition. However, when bleeding occurs, the woman should be managed accordingly. If bleeding is not managed on time, it can lead to potential complications including death of either the baby, the mom or both.

If you have placenta previa, your doctor will have to assess the amount of bleeding, how far you are in your pregnancy, your general health, the baby’s health and the position of the placenta as well as the baby. The main goal is to maintain the pregnancy the closest possible to your due date to prevent the likelihood of having neonatal complications.

If you have little to no bleeding, your doctor is most likely to recommend you to rest and avoid activities such as exercise or sex. You will also have to closely monitor any bleeding and seek medical help as soon as it happens. Your doctor will best advise on the ideal mode of delivery, either vaginal or caesarean delivery depending on the position of the placenta.

If you have heavy bleeding, it is important that you seek medical help as soon as possible. You may even in some cases need blood transfusion if you have lost a large quantity of blood. You may end up needing a caesarean section immediately to deliver your baby if the bleeding cannot be controlled or if the baby is in distress. If the delivery has to be done prior to 37 weeks of pregnancy, your doctor may give you corticosteroids to ensure maturation of your baby’s lungs.

What are the complications of placenta previa?

With advances in technology and imaging techniques, early diagnosis of placenta previa can be made. However, some complications can still arise in the case of placenta previa. These include:

Maternal complications

• Haemorrhage (postpartum bleeding which is bleeding after delivery of the baby)
• Need for blood transfusion
• Placental abruption (Separation of the placenta from the uterine wall)
• Preterm delivery (Delivery of the baby prior to 37 weeks of pregnancy)
• Inflammation of the endometrium
• Death (in 2-3% of cases)

Infant complications

• Congenital malformations
• Fetal intrauterine growth retardation
• Fetal anemia
• Abnormal fetal presentation, meaning that the baby’s position during delivery is abnormal, for example, breech presentation (presenting the buttocks first instead of the head)

• Low birth weight
• Jaundice at birth
• Admission into the neonatal intensive care unit

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