Placental Abruption

Placental 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

Ananth, C.V., et al. (2021). Maternal Cardiovascular and Cerebrovascular Health After Placental Abruption: A Systematic Review and Meta-Analysis (CHAP-SR). American Journal of Epidemiology, 190(12), 2718-2729.

The researchers found that placental abruptions significantly increased maternal coronary heart disease and stroke mortality risks.

Odendaal, H., et al. (2020). Associations of maternal smoking and drinking with fetal growth and placental abruption. European Journal of Obstetrics & Gynecology and Reproductive Biology, 253, 95-102.

This study found that cigarette and alcohol consumption combined with other risk factors increased the placental abruption risk.

Fadl, S.A., et al. (2019). Placental abruption and hemorrhage—review of imaging appearance. Emergency Radiology, 26(1), 87-97.

This study looked at how placental abruptions appear on ultrasounds, CT scans, and MRIs. The researchers found that it was difficult to conduct placental evaluations based on CT scans. However, they also found that MRIs helped determine the hematoma’s age and differentiate them from tumors.

Li, Y., et al. (2019). Analysis of 62 placental abruption cases: Risk factors and clinical outcomes. Taiwanese Journal of Obstetrics and Gynecology, 58(2), 223-226.

This study looked at placental abruption’s clinical characteristics and outcomes. The researchers found that preeclampsia and premature membrane rupture were the primary risk factors. They also found that abdominal pain and bleeding were placental abruption’s classical symptoms. Emergency C-sections were performed in over 70 percent of placental abruption cases. The researchers recommended that healthcare providers should consider symptoms, risk factors, physical signs, ultrasound monitoring, and cardiac care when diagnosing a placental abruption. They concluded that earlier diagnoses and treatments would improve the prognosis of the mother and baby.

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, 66, 8-16.

This study identified genetic loci and related functions that potentially determine the placental abruption risk. The researchers concluded that understanding these genetic factors may help prevent and timely diagnose the condition.

Ananth, C.V., et al. (2015). Change in paternity, risk of placental abruption and confounding by birth interval: a population-based prospective cohort study in Norway, 1967–2009. BMJ Open, 5(2), e007023.

This study found no association between partner changes between pregnancies and placental abruptions.

Shen, T.T., et al. (2008). A population-based study of race-specific risk for placental abruption. BMC pregnancy and childbirth, 8(1), 1-9.

This study found that Black women were more at risk of suffering a placental abruption than white women.

Birth Injury