Placental Abruption

What is it?

It is important to distinguish between a premature placental abruption and a placental separation area found during a routine exam. The first case, known to obstetricians as placental abruption, refers to a medical emergency in which the placenta, normally implanted, suddenly and abruptly detaches from the uterus — thereby interrupting the supply of oxygen and nutrients to the fetus

This situation occurs after 20 weeks of pregnancy and results from the rupture of arteries that supply the placental area. The main cause is high blood pressure, but it can also result from trauma, cocaine use, or other less common situations

The presence of a placental separation area is due to the rupture of small veins behind the placenta, causing part of it to detach from the uterus. The cause is unknown, but when it occurs early in pregnancy (before 20 weeks), it is classified as a threatened miscarriage

When is it most common during pregnancy? (Third trimester?)

Although placental abruption can occur from the 20th week of pregnancy (fifth month), it is fortunately more common in the third trimester, after 28 weeks — a time when the fetus is already viable, meaning it has the ability to survive outside the womb

On the other hand, placental separation areas are more common in the first trimester, especially before 12 weeks, when they are classified as a threatened miscarriage, as mentioned above. They can also occur later in pregnancy, particularly if the placenta is implanted near the cervix, where its attachment is more fragile

Symptoms

Once again, the conditions of placental abruption and areas of placental detachment are quite distinct. Placental abruption is characterized by continuous, intense cramping pain, accompanied by a “hardening” of the uterus, known as uterine hypertonia

About 80% of women experience vaginal bleeding, which varies in amount and is dark red in color. However, not all affected women exhibit external bleeding, as it may remain trapped behind the placenta or enter the amniotic sac—making the amniotic fluid bloody, a condition known as hemamnios.

Fetal heartbeats often show a progressive decrease, but due to the uterine hardening, auscultation can be significantly hindered

When there is a localized area of placental detachment, vaginal bleeding may occur, typically bright red and painless, with normal uterine tone. However, in many cases, there is no visible bleeding, and the condition is discovered incidentally during an ultrasound exam. Except in cases of very heavy bleeding, the baby’s well-being is usually preserved

Diagnosis

The diagnosis of placental abruption is primarily clinical, especially because swift action is required and there is no time for additional tests. In cases involving a localized area of placental detachment, there may be a clinical suspicion, but confirmation is made through obstetric ultrasound examination

Will labor need to be induced if placental abruption is confirmed?

In cases of placental abruption, if the fetus is alive and viable, delivery must be immediate. This is not only to prevent fetal death but also to avoid the mother's body from consuming all its clotting factors in a futile attempt to stop the bleeding

Such a situation can worsen the condition and lead to bleeding in other areas. If the fetus has died, spontaneous delivery can be awaited for up to 4 hours, provided the mother is stable and there is no significant consumption of clotting factors—meaning close monitoring and testing are essential

For a localized area of placental detachment, if maternal and fetal well-being is preserved, the approach is expectant management—that is, observation only. Naturally, avoiding local microtraumas, such as those caused by sexual intercourse, is crucial to prevent worsening of the bleeding

As long as there is no active bleeding, there is no need to induce labor—the pregnancy can continue until a more appropriate time. It is worth noting that in most cases of placental detachment, especially in the first trimester, the condition resolves as the placenta grows

Treatment

In cases of placental abruption, since immediate delivery is required, hospitalization is mandatory. In contrast, for localized areas of placental detachment, if maternal and fetal well-being is ensured and there is no active bleeding, hospitalization is not necessary. The recommendation is simply to seek medical attention if the condition worsens

The use of micronized vaginal progesterone has shown some benefit in the literature for maintaining pregnancy and improving the condition

Risk Factors

For placental abruption, the main risk factor is high blood pressure (hypertension). Therefore, blood pressure control is essential for preventing this condition. The use of vasoconstrictive drugs, such as cocaine, is another important risk factor and must be strictly avoided

For localized areas of placental detachment, the main risk factor is low placental implantation. Other associated factors may include advanced maternal age and chromosomal abnormalities

By the Einstein Editorial Board