What is an embolism during pregnancy?
An embolism is an obstruction of a blood vessel by an embolus, something that has traveled through the bloodstream. In obstructing blood flow, an embolism can cause ischemia (inadequate blood flow and oxygen to tissue), which in turn can lead to infarction, tissue death. Embolic infarction has different names and effects, depending on where in the body it happens. The obstruction of pulmonary vessels from an embolus is called a pulmonary embolism (PE). The obstruction of coronary vasculature (blood vessels of the heart) has different names, depending on the extent of infarction. Whereas most vascular obstruction in the heart comes, not from emboli, but from blood clots forming at the site, embolism constitutes a high proportion of blood vessel obstruction in the brain, known as ischemic stroke. A stroke due to embolism is called either a cerebral embolism (CE), or an embolic stroke. Embolism also can occur in various other organs in the body, but when it comes to pregnancy and the weeks following delivery, the main embolism concerns are first PE and second CE. In pregnancy, PE is the more common type of embolism, because the main source of emboli in pregnant women is venous thrombosis, the formation of clots in deep veins. This is due to whats called an increased hypercoagulability state (meaning that in pregnancy, you form clots more easily) and due to venous stasis, meaning that blood slows down and pools in certain veins, due to pressure of the growing womb on veins in the pelvis. Deep venous clots can produce emboli, which travel through the right side of the heart and to the lungs until they reach vessels too narrow to allow them to pass through – this causes a PE.
Although normally, such emboli generated in deep veins would not travel beyond the lungs and cause an embolism in the brain, in many people, venous emboli can reach the left side of the heart through what is called a patent foramen ovale (PFO), an opening between the hearts right and left atria. The foramen ovale is present in everybody during fetal life and closes soon after birth, but possibly as many as one-third of all people have a PFO. Additionally, certain types of emboli can be generated in places other than deep veins. A very rare, but severe, pregnancy complication, for instance, is amniotic fluid embolism (AFE), caused by amniotic material traveling in the mothers bloodstream. This can produce an embolism in the brain and other organs. Also, the heart can be a source of emboli that reaches the brain, either because of heart surgery, problems with a valve on the left side of the heart (aortic valve and mitral valve), an infection of the inner layer of the heart (endocarditis), an aneurysm in the wall of the heart, or atrial fibrillation ([AF] quivering of the upper chambers of the heart without active pumping of the blood into the ventricles).
How common is embolism during pregnancy?
Venous thromboembolism (VTE), the condition that encompasses venous thrombosis and resulting embolic complications, develops in 0.5-2.2 cases for every 1,000 pregnancies. The thrombosis risk, and thus the risk of embolism, is especially high at particular times. In the late first trimester, the risk is elevated, for instance, possibly due to the coagulation system shifting toward increased clotting to protect against bleeding in placental blood vessels, thereby lowering the risk of spontaneous abortion (miscarriage). From the middle of pregnancy onward, the tendency for clotting decreases slightly, but then it rises to a very high peak just after delivery. The risk remains elevated for several weeks after delivery. Because of the timing of body changes in pregnancy, embolism is possible during the post-partum period, from delivery until about two weeks after delivery. There have been a handful of epidemiological studies, reporting rates of stroke, consisting mostly of cerebral embolism affecting up to 34 pregnant women per 100,000 deliveries. Still, it is difficult to state how common cerebral embolism is in terms of a precise number.
How is embolism during pregnancy diagnosed?
Diagnosis of PE must proceed quickly, beginning with a high-level suspicion that you might have a PE based on difficulty with your breathing. Doctors can then check for a PE with a procedure called a ventilation/perfusion (V/Q) scan, which analyzes air flow using a radioactive substance. Another method for diagnosing PE is computed tomographic pulmonary angiography (CT-PA). Some pulmonary specialists prefer using simple flat x-ray scans (CXR) instead of CT-PA to minimize the radiation dose to the fetus, although CT-PA is a better test for detecting PE. Since PE is an emergency that can be fatal quickly both to the mother and fetus, concern about scanning radiation is not appropriate. Along the way, the team caring for you will also monitor vital signs, which include pulse oximetry, which can reveal whether your lungs are not functioning in providing oxygen to the blood.
To assess for CE, the physical examination will include a neurological exam that will provide clues as to the location of the embolism. Diagnosis can be achieved using computed tomography (CT) scanning or magnetic resonance imaging (MRI) of the brain, plus doctors also may order a cerebral angiogram; in this test, a catheter is inserted through a small incision and into an artery in your neck so that dye can be injected to provide contrast to show details of blood vessels. Additional tests may include carotid ultrasound that provides images of the inside of your carotid arteries. You may be tested with echocardiography to find a location in the heart that may be generating emboli. The workup will also include an electrocardiogram (ECG), which can be helpful in diagnosis if a cardiac condition, such as AF, is the reason for the embolism.
Does embolism cause problems during pregnancy?
Yes. PE can be quickly fatal because it interferes with lung function. CE can produce temporary or permanent disability and can be fatal, as well. Disabilities that often occur in embolic strokes include problems with speech or understanding of speech and paralysis of particular parts of the body, such as the face, arms, or legs. Typically, one side of the body or face is affected.
Does embolism cause problems for the baby?
Yes, because it threatens the mothers life and ability to function. In addition to PE and CE being the main embolism concerns, its possible for any embolus traveling in the mothers arterial system to reach the vasculature of the uterus and placenta, causing a cutoff of circulation to the fetus in a way that the mother survives, but the fetus does not.
What to consider about taking medications when you are pregnant or breastfeeding:
- The risks to yourself and your baby if you do not treat the embolism
- The risks and benefits of each medication you use when you are pregnant
- The risks and benefits of each medication you use when you are breastfeeding
What should I know about using medication to treat embolism during pregnancy?
Treatment for embolism is based on the rapid provision of medications that can break up the clot to restore blood flow to the affected area, whether in the lungs, the brain, or an
ywhere else, and the prevention of additional emboli from forming. In the case of PE, physicians do this with an agent called heparin, which binds to an anti-clotting factor called anti-thrombin. This inhibits two very important clotting factors, resulting in reduced clotting and breakup of the clot. There are different types of heparin. Low molecular weight heparin (LMWH) is often the choice during pregnancy. When no LMWH is available, doctors can use another type of heparin called unfractionated heparin (UFH). In severe cases, when the thrombus does not break up with heparin alone, you may receive thrombolytic (clot breaking) therapy, consisting of streptokinase, r-tPA, or urokinase. Thrombolytic therapy carries a risk of bleeding, but the risk from an un-dissolved venous clot can be worse.
Heparin is used for short-term therapy, but if the PE occurs in the middle of pregnancy, very often, the heparin therapy will be continued for months. On the other hand, your doctor may switch you to long-term anticoagulation treatment. The classic medicine in this category is warfarin, which cannot be given during the first trimester (especially weeks 6-12) because it causes birth defects nor within a few weeks of delivery. Although there are newer blood thinners, generally, they are not thought to be safer than warfarin, but if needed, warfarin can be given in the middle of pregnancy if your doctor thinks your risk of clotting is great. Otherwise, there are other options, one common one being low-dose aspirin, which has been used in many pregnancies without harm. The decision to provide you with long-term anticoagulation therapy and the needed duration of that therapy depends on your medical history.
When it comes to embolic stroke, anti-clot therapy often is quite aggressive, because its very important to restore blood flow. Quick recognition of the stroke is a major factor in determining the treatment. The gold standard treatment consists of drugs of a category called thrombolytic agents that also can be used in PE, as noted above. These drugs can be given intravenously, or endovascularly, meaning through an instrument in a catheter that is inserted into a vein. Although clot-busting drugs are considered to be a risk for the fetus, such drugs have been administered successfully in pregnancy, and the risk must be weighed against the risks and benefits of giving the drug and the risk of not.
Who should NOT stop taking medication for embolism during pregnancy?
If you have an embolism during pregnancy, taking the medication is a matter of life and death, so no one should stop taking the medication until it is ended by order of your physician.
What should I know about choosing a medication for my embolism during pregnancy?
It is important to stay in communication with your health care provider as the release of new studies over time can change the outlook on the role of specific medications during pregnancy.
You may find Pregistrys expert reports about the medications to treat this condition here. Additional information can also be found in the sources listed below.
What should I know about taking a medication for my embolism when I am breastfeeding?
There is some concern about aspirin because it enters breastmilk, but it enters in very tiny amounts. Neither UFH nor LMWH is thought to be harmful in breastfeeding, but after a heart attack, you are likely to be on various medications, some of which may require you to avoid breastfeeding. Neither warfarin (used in North American for long-term anticoagulation therapy) nor a similar drug called acenocoumarol (used in Europe) enter breastmilk or otherwise affect a nursing infant. Thus, once you have delivered, warfarin therapy can be added or added back.
What alternative therapies besides medications can I use to treat my embolism during pregnancy?
An embolism is life-threatening and requires anti-clot medication.
What can I do for myself and my baby when I have embolism during pregnancy?
It is very important to follow the instructions of your physician.
Resources for embolism in pregnancy:
For more information about embolism during and after pregnancy, contact http://www.womenshealth.gov/ (800-994-9662 [TDD: 888-220-5446]) or contact the following organizations:
- Mayo Clinic. Pulmonary Embolism.
- Weil Cornell. What Every Woman Should Know about Pregnancy and Pulmonary Embolism