Placental abruption: Clinical sciences

Placental abruption is the partial or complete separation of the placenta from the uterine wall prior to delivery. This is due to rupture of maternal vessels within the basal layer of the endometrium. Blood accumulates and splits the placental attachment, which can cause leakage of blood into the myometrium, painful uterine contractions, as well as maternal blood loss through the vagina, which results in decreased blood flow and oxygenation to the fetus.

Some patients may present acutely requiring immediate delivery, while others may stabilize and be candidates for expectant management of the pregnancy with close surveillance.

When evaluating a patient presenting with a chief concern suggesting placental abruption, your first step is to perform a CABCDE assessment as well as a primary obstetric survey to determine if they are stable or unstable. If the patient is unstable, immediately attempt to control the hemorrhage and stabilize their airway, breathing, and circulation. You may need to intubate the patient, obtain IV access, and continuously monitor their vitals. Remember that you have two patients here, so you must assess the fetus as well! First, check the fetal heart rate to ensure well-being, and if at a viable gestational age, perform continuous fetal monitoring and assess for fetal movement. Bleeding from a placental abruption can stimulate uterine contractions, so you should also assess for labor.

Once you have initiated the acute management, your next step is a focused history and physical exam. Labs are important because of the potential for life-threatening hemorrhage, so order a CBC as well as PT, INR, PTT, and fibrinogen. Finally, order a Kleihauer-Betke test, also called a “KB” for short, to look for the presence of fetal blood in maternal circulation. This test is highly specific for abruption and lets you know how much Rh immune globulin is needed to prevent alloimmunization.

In the history, patients may report feeling dizzy or anxious, and may experience tunnel vision due to the acute hemorrhage. In addition, they’ll typically report abdominal pain and contractions. Next, be sure to review the patient’s risk factors for abruption. These include tobacco or cocaine use; abdominal trauma; preterm prelabor rupture of membranes; advanced maternal age; uterine myomas; a history of abruption in a prior pregnancy; or a hypertensive disorder, such as gestational hypertension, preeclampsia, or chronic hypertension.

Here’s a clinical pearl! Painful vaginal bleeding after 20 weeks often indicates a placental abruption. With painless vaginal bleeding, think placenta previa.

As for the physical exam, expect hypotension, tachycardia, and an altered mental status. Patients may look pale and their skin could feel cold or clammy. Typically, patients will have vaginal bleeding coming from the uterus, but in cases known as a concealed abruption, the blood can pool behind the placenta, so there won’t be vaginal bleeding.

Blood leaking into the myometrium may make the uterus tender, firm, and hypertonic on the exam. Now, the rupture of vessels that provide maternal blood to the fetus and the loss of functional placental surface can cause fetal distress.

The fetal heart rate tracing may show recurrent late decelerations

or even fetal bradycardia. Additionally, the tocometer often shows high frequency, low amplitude contractions, and increased uterine resting tone.

Because some women with abruption present without vaginal bleeding, keep abruption in mind for women who present with decelerations and uterine irritability during monitoring.

Now let’s talk about labs. Anemia is common in abruption. In addition, there may also be low platelets, elevated PT, INR, and PTT, as well as low fibrinogen as coagulation factors are consumed. Lastly, labs may also show a positive KB.

Alright, based on these findings on history, physical, and labs, you can diagnose placental abruption with hemorrhage and shock. Start IV fluid resuscitation quickly, and be prepared to give blood products, even if labs seem reassuring. Remember that labs may not reflect the degree of blood loss, since hemorrhage can rapidly evolve, and it takes time for lab values to reflect that. Therefore, the patient’s clinical picture and vitals should serve as the main indicators for transfusion.