he American College of Obstetricians and Gynecologists (2017 c) notes that a deinitive causal link cannot be made between inherited thrombophilias and adverse pregnancy outcomes. Moreover, in one randomized trial, Rodger and associates (2014) found that antepartum prophylactic LMWH did not reduce a composite outcome of pregnancy loss, severe or early-onset preeclampsia, small-for-gestational age neonates, and TE in thrombophilic women.
Thus, because of uncertainties in the magnitude of risk and in the beneits of prophylaxis given to prevent pregnancy complications in women with heritable thrombophilias, it remains unproven that universal screening is indicated (Louis-Jacques, 2016). In contrast, the association between APS and adverse pregnancy outcomes-including fetal loss, recurrent pregnancy loss, and preeclampsia-is much stronger.
Given the relatively high incidence of thrombophilia in the population and the low incidence of TE, universal screening during pregnancy is not cost efective (Carbone, 2010). hus, a selective screening strategy is required. he American Academy of Pediatrics and the American College of Obstetricians and Gynecologists (2017) recommend that thrombophilia screening be considered in the following clinical circumstances: (1) a personal history ofTE that was associated with a nonrecurrent risk factor such as fractures, surgery, and/or prolonged immobilization; and (2) a irst-degree relative (parent or sibling) with a history of high-risk thrombophilia or VTE before age 50 years in the absence of other risk factors.
The American College of Obstetricians and Gynecologists (2017 c) notes that testing for inherited thrombophilias in women who have experienced recurrent fetal loss or placental abruption is not recommended because clinical evidence that antepartum heparin prophylaxis prevents recurrence is insuicient. Similarly, testing is not recommended for women with a history of fetal-growth restriction or preeclampsia. The American College of Chest Physicians also recommends against screening women with prior pregnancy complications (Bates,
TABLE 52-4. How to Test for Thrombophilias
Is Testing Is Testing Reliable Reliable Is Testing During During Acute Reliable with Testing Method Pregnancy? Thrombosis? Anticoagulation?
alf screening in pregnancy is necessary, cutoff values for free protein S antigen levels in the second and third trimesters been identified at less than 30% and less than 24%, respectively.
Reproduced with permission from American College of and Gynecologists Women's Health Care Physicians:
ACOG Practice Bulletin No. 138: Inherited thrombophilias in pregnancy, Obstet Gynecol. 20103 Sep;122(3):706-717.
2012). However, screening for antiphospholipid antibodies may be appropriate in women who have experienced a fetal loss or early-onset preeclampsia (Berks, 2015).
Methods of screening for the more common inherited thrombophilias are shown in Table 52-4. Whenever possible, laboratory testing is performed at least 6 weeks after the thrombotic event, while the patient is not pregnant, and when she is not receiving anticoagulation or hormonal therapy. Screening for hyperhomocysteinemia is not recommended (American College of Obstetricians and Gynecologists, 2017 c).