Dose Adjusting Enoxaparin Thromboprophylaxis Dosage According to Anti-factor Xa Plasma Levels Improve Pregnancy Outcome
Status:
Completed
Trial end date:
2015-08-01
Target enrollment:
Participant gender:
Summary
The risk of venous thromboembolism increases in pregnancy. Thrombophilia whether genetic or
acquired, is a hypercoagulable disorder that may increase the risk of venous thromboembolic
events. Clinically, these events are presented as maternal deep vein thrombosis and pulmonary
emboli. Thrombophilias are also associated with adverse fetal outcomes including intrauterine
growth restriction, intrauterine fetal death, severe preeclampsia, placental abruption and
recurrent abortions.
Pregnant women who experienced one or more of the above complications are advised to be
examined for the presence of the genetic or the acquired form of thrombophilia.
Low molecular weight heparin prophylaxis, an anticoagulant, is advised for pregnant women
with a history of thromboembolism, and many experts recommend prophylaxis for pregnant
patients with a known thrombophilia and history of adverse pregnancy outcomes associated with
these hypercoagulable states.
Physiologic changes in normal pregnancy, including weight gain, increased renal clearance and
volume of distribution, may decrease the availability of low molecular weight heparin
(Enoxaparin or Dalteparin), or produce a less predictable response in pregnant women compared
with nonpregnant women. There are no clear recommendations for use of prophylactic low
molecular weight heparin in pregnancy. Clinicians tend to use doses suggested for nonpregnant
patients. Regarding pregnant patients taking enoxaparin or dalteparin, the American College
of Obstetricians and Gynecologists states that "because of the lack of data regarding
adequate dosing during pregnancy, anti-factor Xa levels may be monitored".
Two recently published studies demonstrated that plasma anti-factor Xa levels during
pregnancy were lower than expected, indicating that many pregnant patients may receive a
subprophylactic dosing.
Our objective is to check pregnancy outcome among thrombophilic women treated with an
adjusted enoxaparin thromboprophylaxis dosage according to anti-factor Xa plasma levels
compared to women with fixed dosage.