Placental Abruption

Pregnant Mother in DistressPlacental abruption (also called "placenta abruptio") is an uncommon and potentially dangerous complication during pregnancy in which the placenta prematurely detaches from the uterus before birth.

The placenta is an organ that plays a critical role in pregnancy and gestation. The placenta is responsible for delivering nutrients from the mother to the baby during pregnancy. In a normal pregnancy, the placenta attaches to the upper part of the uterus and stays attached until the baby is delivered. The separation of the placenta from its site of implantation before the delivery of the fetus is called placental abruption.

So placental abruption occurs when the placenta detaches and separates from the uterus prematurely before the baby is born. You do not see abruptions before 20 weeks. Placental abruption typically occurs around the 25th week of pregnancy. But it is not a common complication. Placental abruption only affects between 1% and 6% of all pregnancies.

Placental abruption may be occult and not associated with uterine pain, tenderness, and bleeding. Placental abruption can occur with little or no external signs of injury to the abdominal wall.

What are the Symptoms of Placental Abruption?

In the earliest stages of placental abruption (when the placenta first begins to detach from the uterus) there may not be any noticeable symptoms at all. When symptoms appear later on they tend to show up very suddenly and be very intense. Sudden vaginal bleeding is the primary symptom of placental abruption. Around 80% of women who experience placental abruption will have vaginal bleeding. The remaining 20% of placental abruption cases do not result in vaginal bleeding, usually because the detached placenta is positioned in a way the effectively traps the blood. The other key symptoms of placental abruption include:

  • Sudden and often severe pain in the abdomen or back
  • Abdominal tenderness
  • General discomfort

Placental abruption's limitation of oxygen and nutrients is likely going to have an impact on the growth of the fetus. The size of the baby is testable. Placental abruption is the leading cause of fetal growth restriction (or IUGR). Sometimes, IUGR is misdiagnosed as "constitutionally small" which just means the child is little and healthy the way some adults are little and healthy. The key is for the obstetrician and the maternal-fetal medicine doctors to be able to distinguish between the two.

What are the Causes and Risk Factors of Placental Abruption?

In some cases, placental abruption is caused by bleeding resulting from some sort of abdominal trauma to the mother. Car accidents are a common cause of external trauma to a pregnant woman's abdomen.

In most other cases, however, the exact cause of the placental abruption is not fully known. There are a number of well-known risk factors that have been shown to increase a woman's likelihood of experiencing a placental abruption. The most commonly recognized risk factors for placental abruption are:

  • Maternal Age: older mothers are much more likely to experience placental abruption compared to younger mothers, so maternal age over 35 increases the risk of placental abruption.
  • Multiples: a pregnancy with multiples (e.g., twins, triplets, etc.) makes abruption more likely, especially for the 2nd baby because the placenta frequently detaches after the first baby is delivered.
  • High Blood Pressure: a maternal history of hypertension (high blood pressure)
  • History of Abruption: mothers who had a placental abruption in a prior pregnancy are 10 times more likely to have one again in a subsequent pregnancy.
  • Smoking: a recent study found that women who were regular cigarette smokers before getting pregnant, increased their chance of placental abruption by 40% for each year that they smoked.
  • Cocaine: cocaine use during the 3rd trimester of pregnancy increases the chance of placental abruption from 1% to 10%.
How is Placental Abruption Diagnosed?

Placental abruption cannot be diagnosed definitively until after the baby is delivered and there are few markers for placental abruption, particularly in the first to trimesters. However, doctors will often suspect placental abruption and may have evidence to support that suspected diagnosis. Diagnostic testing for placental abruption usually starts with a physical examination of the mother followed by an ultrasound or sonogram imaging test. Blood work and fetal monitoring devices might also be used to gather information and decide on the most appropriate course of action.

What are the Treatment Options for Placental Abruption?

The appropriate method for treating or managing placental abruption will depend on the timing and severity of the placental abruption. If placental abruption occurs it will always require c-section delivery. If the abruption is considered "mild" doctors may opt to wait as long as possible to deliver the baby. If the abruption is severe an emergency c-section may be necessary.

Mild Placental Abruption

Just under half (48%) of placental abruptions are classified as "mild" in severity. Placental abruptions are considered mild when they involve limited vaginal bleeding Maternal heart rate and blood pressure remain stable will remain stable. Most importantly, there are no indications of fetal duress. For mild placental abruptions that occur before the 34th week of gestation, doctors will usually try to prolong the pregnancy as long as possible. Management will typically involve medication to prolong gestation and very close monitoring. Best rest or possibly hospital care is also standard. When a mild placental abruption occurs closer to the end of the pregnancy (after the 34th week), doctors will usually recommend delivering the baby right away. This will involve either an emergency C-section or inducing labor.

Moderate or Severe Placental Abruption

Placental abruptions are considered moderate or severe when vaginal bleeding is heavy or moderate and the abruption triggers maternal tachycardia or elevated blood pressure. When the placental abruption is moderate or severe, immediate delivery of the baby is typically required regardless of how far along the pregnancy is. If the bleeding from the placental abruption is particularly heavy, a blood transfusion may be necessary. Although rare, some placental abruptions trigger uncontrolled bleeding which can only be stopped by performing an emergency hysterectomy (surgical removal of the uterus).

In 2020, this is a clinical trial to determine if azithromycin helps with pre-labor rupture of membranes. Doctors sometimes prescribe erythormycin which can be so brutal on a woman's stomach that she discontinues the use of the drug.

Placental Abruption Medical Literature
  • Workalemahu T, et. al (2018) Genetic variations and risk of placental abruption: A genome-wide association study and meta-analysis of genome-wide association studies. Placenta. 2018;66:8-16. Study found there is genetic component to the risk of placental abruption.
  • Ananth CV, et. al (2015): Change in paternity, risk of placental abruption and confounding by birth interval: a populationbased prospective cohort study in Norway, 1967-2009. BMJ Open.2015; 5:e007023. Study shows women who do not have an abruption in their first pregnancy, have a threefold increased risk for abruption if the birth intervals are less than a year.
  • Shen TT, et al. A population-based study of race-specific risk for preterm premature rupture of membranes [electronic article], Am J Obstet Gynecol, 2008, vol. 199 4pg. 373. Study shows that race is associated with greater risk of placental abruption, specifically with respect to black and white mothers. Black women have a might greater risk.