Will pregnancy continue if anticoagulants are given to treat Pulmonary Embolism (PE)?

Anticoagulant Treatment for Pulmonary Embolism During Pregnancy

Yes, pregnancy can safely continue when anticoagulants are administered to treat pulmonary embolism (PE). 1 Low molecular weight heparin (LMWH) is the recommended first-line therapy for PE during pregnancy and does not adversely affect the continuation of pregnancy.

Recommended Anticoagulation for PE in Pregnancy

First-Line Treatment

• LMWH is strongly recommended over unfractionated heparin (UFH) for the treatment of VTE in pregnancy (Grade 1B recommendation) 2, 1
• LMWH options include:
  • Enoxaparin: 1 mg/kg twice daily or 1.5 mg/kg once daily
  • Dalteparin: 100 units/kg twice daily or 200 units/kg once daily
  • Tinzaparin: 175 units/kg once daily 1

Alternative Options

• UFH is an alternative for patients with severe renal impairment or high bleeding risk
  • Target aPTT between 1.5-2.5 times control 1
• Important contraindications:
  • Vitamin K antagonists (warfarin) are contraindicated during the first trimester and last 6 weeks of pregnancy 2, 1
  • Direct oral anticoagulants (DOACs) are contraindicated throughout pregnancy due to placental transfer 1

Safety Profile and Pregnancy Outcomes

• LMWH does not cross the placenta and has not been associated with teratogenicity or increased risk of major developmental abnormalities 3
• The FDA label for enoxaparin states: "Human data from a retrospective cohort study, which included 693 live births, suggest that enoxaparin does not increase the risk of major developmental abnormalities" 3
• Case reports have demonstrated successful treatment of PE during pregnancy with LMWH without adverse pregnancy outcomes 4
• A case-control study comparing pregnant patients treated with LMWH to untreated controls found no significant difference in bleeding complications 5
• In a retrospective study of 111 pregnancies where LMWH was started in the first trimester, the fetal loss rate was only 6.3%, which is not higher than the general population 6

Duration of Treatment

• Anticoagulation should be continued throughout pregnancy and for at least 6 weeks postpartum
• The minimum total duration of therapy should be 3 months 2, 1

Management Around Delivery

1. Discontinue subcutaneous heparin at the onset of regular uterine contractions 2, 1
2. If delivery is planned, LMWH should be discontinued at least 12-24 hours before anticipated epidural placement 1
3. For patients with PE within the last 3 months, peri-partum intravenous heparin may be used, with infusion discontinued 4-6 hours prior to expected delivery 2
4. Epidural anesthesia should be avoided unless LMWH has been discontinued for at least 12 hours 1

Monitoring and Follow-up

• Regular assessment of bleeding parameters (hemoglobin, platelets, coagulation studies)
• Anti-Xa monitoring in specific situations (extremes of body weight, renal impairment)
• Multidisciplinary team approach involving obstetricians, hematologists, and pulmonary/critical care specialists 1

Potential Complications

• Risk of major bleeding with therapeutic LMWH is approximately 1.98% 1
• Potential side effects include local reactions at injection site, allergic reactions, thrombocytopenia, and rarely osteoporosis with long-term use 3
• Hemorrhage can occur at any site and may lead to maternal and/or fetal death, though this is rare with proper monitoring 3

Special Considerations

For hemodynamically unstable PE (high-risk PE with hypotension, shock, or cardiac arrest):

• Immediate initiation of UFH is recommended despite bleeding risk
• Thrombolysis may be considered only in life-threatening situations with hemodynamic collapse 1, 7
• Maternal survival rate with appropriate treatment is approximately 94% even in high-risk cases 1

The accurate diagnosis of PE is essential before initiating anticoagulation, as it requires prolonged treatment during pregnancy. All diagnostic modalities, including CT scan and angiography, may be used without significant risk to the fetus 2.