Obstetrics 16: Thromboembolic Disease and Pregnancy Portal
Introduction
Thromboembolic disease during or after pregnancy may range
from mild to severe (life-threatening). The health care practitioner
must be comfortable in the evaluation and treatment of thromboembolic
disease.
Incidence and Epidemiology
As many as 3 per 1000 pregnancies are affected by deep vein
thrombosis. Compared to a non-pregnant
woman’s risk of thromboembolic disease, pregnancy and the postpartum
period increases the disease’s risk 5-fold.
Patient Assessment
History
The most important aspect of a patient’s history is previous
thromboembolism. The risk for recurrence is 5% to 15%. Other risk
factors are major surgery (including cesarean section and operative
vaginal delivery), immobilization, inherited deficiencies, and
malignancies.
Examination
Certain signs and symptoms may cause suspicion of thromboembolism, but clinical judgement alone is not
enough to make the diagnosis.
Signs and Symptoms of a Pulmonary Embolus
- Tachycardia
- Fever
- Rales
- Cough
- Pleuritic chest pain
- Dyspnea
- Apprehension
- Hemoptysis
- Diaphoresis
- Cyanosis
- Hypotension
- Tachypnea (resting rate >16)
- Syncope
- Friction rub
- Loud S2
- Gallop or murmur
Clinical Findings Suggestive of Deep Venous Thrombosis
- Leg swelling
- Pain/tenerness
- Warmth
- Palpable cord
Measurements of lower extremity circumference that show a 2 cm difference are significant. Dorsiflexion of the foot (Homans’ sign) is considered positive if it elicits pain.
Diagnostic Studies
The diagnosis of deep venous thrombosis may be made by
venography or Doppler screening. Venography is considered the gold
standard, but Doppler screening is much less invasive. Unfortunately,
Doppler screening is not as sensitive. During pregnancy, a combination
of venography and Doppler screening is often used to make a diagnosis.
For suspected pulmonary embolus, ABGs, ECG, chest x-ray,
ventilation-perfusion scan, CT scan, and pulmonary angiography (if
needed) are used for diagnosis.
Treatment
Superficial thrombophlebitis may be treated with elevation,
analgesia, elastic stockings, heat, and ambulation. Deep venous
thrombosis below the knee is often treated conservatively with
adjunctive measures, but any evidence of progression requires heparin
therapy. Deep venous thrombosis above the knee always needs heparin
therapy. The most common approach has been an IV bolus of regular
Heparin 5000 to 10 000 units followed by continuous infusion at 1000
U/hour. Make adjustments based on serial PTT measurements. Normally the
PTT is kept at 1.5 to 2.0 times control. An alternative is enoxaparin
sodium (Lovenox), a low molecular weight heparin, 1 mg/kg SQ every 12
hours. Prior to initiation of therapy, draw coagulation studies and
monitor periodically.
Resuscitation and stabilization are of the first priority when pulmonary embolus is suspected. Use oxygen, cardiopulmonary resuscitation, or ventilatory support as needed. Pregnancy is a relative contraindication to systemic thrombolytic therapy and is restricted to life-threatening situations as thrombolytics themselves may cause life-threatening hemorrhage. Rapid anticoagulation is achieved in the same fashion as for deep venous thrombosis with the use of heparin IV.
Intra- and Postpartum Management
Controversy exists regarding dosage and duration of heparin
therapy during and after pregnancy. Multiple regimens are available.
Oral anticoagulation is contraindicated throughout pregnancy but may be
used postpartum if the patient is not breast-feeding. Coumadin use
while breast-feeding is controversial.
Delivery while on anticoagulaion therapy is associated with an increased risk of bleeding. This is especially true if a cesarean section or an episiotomy has been necessary. Regional anesthetics are not recommended. There are several approaches to avoid bleeding complications during delivery. With most women, simply stopping the heparin is acceptable. Others may need to continue the lowest therapeutic dose of heparin. Another approach is to stop the therapeutic heparin infusion 4 hours before expected delivery. Protamine sulfate may also be used cautiously to reverse the heparin. Lovenox SQ 1 mg/kg q 12 h may be used during delivery with less risk of bleeding than IV heparin. Patients on prophylactic anticoagulation may stop their heparin during labor and delivery without an increased risk of thromboembolism.
Heparin may be resumed no sooner than 6 hours postpartum. Some recommend waiting as long as 24 hours. There is no clear data on ideal timing, but most resume anticoagulation therapy 12 to 24 hours after delivery.