Abruption

Placental abruption is characterized by a separation of the placenta from the uterine wall. This section contains information on causes, diagnosis, prognosis and other aspects of a pregnancy complicated by abruption.

Contents

What is placental abruption?
Causes
Diagnosis
Risk factors
Management
Role of placental function testing
Prognosis following a pregnancy with abruption

QUICK LOOK

–   Abruption is a potentially serious condition
–   It occurs when the placenta separates from the wall of the uterus before birth
–   This can result in vaginal bleeding and abdominal pain
–   Depending on the severity of the abruption, the baby may need to be delivered by Caesarean section

What is a placental abruption?

Placental abruption, also known as “abruptio placentae,” is a complication in which the placenta separates from the lining of the uterus before birth. Abruption occurs in about 1% of all pregnancies and is an important case of vaginal bleeding late in pregnancy. Abruption usually causes partial separation of the placenta, still having the potential to contribute to baby’s development and maintaining the nutrient supply to the baby. Very rarely, the placenta separates extensively, such that the baby is no longer alive when the diagnosis is made in the hospital. Abruption can result in bleeding from the mother and deprivation of oxygen and nutrients from the baby. In serious cases, the mother can go into shock from blood loss. Most women with abruption bleed vaginally, but unlike placenta previa[k1] , much of the bleeding with abruption can be concealed inside the uterus, behind the placenta. Consequently, these women may experience problems with blood clotting and organ failure and require blood transfusions. For the fetus, placental abruption can lead to premature delivery, asphyxiation (oxygen deprivation) or stillbirth. Both the risks and management of abruption depends greatly on the severity and the week of pregnancy during which it occurs. Therefore, cases are managed on an individual basis.

Causes

Although the cause of abruption is often unknown, it has been linked to trauma or injury to the abdomen, rapid loss of amniotic fluid and underlying placental damage. Abruption is linked to many risk factors as outlined below.

Diagnosis

The diagnosis of abruption is clinical and individualized. Depending on the location and severity of an abruption, it may be revealed (vaginal bleeding) or concealed (behind the placenta). Therefore, it may be suspected that a pregnant woman who presents with abdominal pain and bleeding could have had an abruption. Some abruption can occur behind the placenta, and keep all of the blood contained. These ‘concealed’ abruptions are more difficult to diagnose. Because the blood can get trapped in the uterus by the placenta, the amount of bleeding a woman experiences may not indicate the severity of the abruption. Ultrasounds are of limited use in diagnosing abruptions, since the visibility of the abruption depends on its location, size, and age (how long before the ultrasound they occurred). Studies have indicated that ultrasounds only detect about 50% of abruptions. Other signs of abruption include back and abdominal pain and rapid uterine contractions.

Risk Factors

While there is no way to accurately predict abruption, several factors put women at a higher risk. If a woman is identified as having any of these risk factors, she can be more closely monitored during her pregnancy, or admitted to hospital for safety. Risk factors for placental abruption include:

–        Previous placental abruption
–        High blood pressure
–        Trauma to the abdomen
–        Substance abuse, especially smoking and cocaine use
–        Premature rupture of the membranes
–        Blood clotting disorders
–        Multi-fetus pregnancies (ex. twins or triplets)
–        Advanced maternal age
–        Pre-eclampsia[k2]
–        Polyhydramnios (excess amniotic fluid around the baby)
–        High AFP in the second trimester (see maternal biochemistry[k3] )
–        Low PAPP-A in the first trimester (see maternal biochemistry[k4] )
–        Notching in the uterine artery waveform (see abnormal uterine artery Doppler[k5] )

Management

The management of placental abruption is usually determined specifically for individual cases. This depends largely on the timing of the abruption (whether early or later in gestation), the degree of the severity (complete or partial), and the stability of both the mother and the baby. If the abruption occurs prior to 34 weeks’ gestation, bleeding is minimal and the fetus is healthy, the mother may be admitted to the hospital for careful daily monitoring. Since there is a risk of preterm delivery, the mother will also be given intramuscular steroids to speed up the development of the fetal lungs. If the abruption occurs after 34 weeks’ gestation, labour may be initiated as a result, and often a normal vaginal delivery can occur. If the abruption is severe, immediate delivery by a Caesarean section is needed to save the baby. After birth, if the maternal bleeding cannot be controlled by any other measures, it may be necessary to remove the uterus entirely (hysterectomy).

Role of placental function testing

Identifying women at risk for abruption can help direct appropriate prenatal care. Placental function testing[k6] , which can identify abnormal levels of PAPP-A and AFP, as well as abnormal uterine artery blood flow, collectively can help recognize individual women at risk. Low levels of PAPP-A detected in the first trimester maternal serum screening have been associated with abruption, as have high levels of AFP detected in the second trimester. Furthermore, a Doppler scan can reveal notching in the uterine artery waveforms, which indicates impaired blood flow to the placenta and is also linked to abruption since it causes multifocal placental injury.

Prognosis following a pregnancy with abruption

Immediately following a pregnancy with abruption, the management will depend on a number of factors. If the mother has lost a lot of blood, she may require transfusions of blood and blood products (plasma, platelets, and clotting factors) and a longer stay in the hospital. Babies may be admitted to the NICU (neonatal intensive care unit) for more rigorous monitoring if they suffered negative consequences of abruption (oxygen deprivation) or with low birth weight due to prematurity.

If the abruption was severe and the bleeding could not be controlled, the uterus may need to be removed (Caesarean hysterectomy) to stop the bleeding. For women who are able to conceive again, one of the primary risk factors for an abruption is a previous abruption, which increases the risk 15-20 fold. Previous abruption also puts women at risk for pre-eclampsia[k7]  in subsequent pregnancies. Therefore, women who have suffered this complication are advised to seek advice from an obstetrician or a maternal fetal medicine specialist to plan the best outcome possible. Women can help by reducing their risk factors, for example, by quitting smoking.

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