Most recommendations regarding thromboprophylaxis during pregnancy stem from consensus guidelines. In one review of guidelines for thromboprophylaxis in pregnancy, the authors concluded that there is a lack of overall agreement about which women should be ofered thromboprophylaxis or ofered testing for thrombophilias (Okoroh, 2012). Bates and associates (2016) also conducted a review of guidelines for obstetrically associated VTE. hey summarized that evidence-based recommendations are based largely on observational studies and extrapolated from data in nonpregnant patients. Similarly, a Cochrane review concluded that evidence is insuicient for firm recommendations regarding thromboprophylaxis during pregnancy (Bain, 2014).
he confusion that has ensued has provided fertile ground for litigators. Cleary-Goldman and associates (2007) surveyed 151 fellows of the American College of Obstetricians and Gynecologists and reported that intervention without a clear indication is common. Table 52-6 lists several consensus recommendations for thromboprophylaxis. In some cases, more than one option is listed, thus illustrating the confusion that currently reigns.
In general, either antepartum surveillance or heparin prophylaxis is recommended for women with prior TE but without a recurrent risk factor, including no known thrombophilia. The study by Tengborn and coworkers (1989), however, suggested that such management may not be efective. hey reported out boembolic disease and were not tested for thrombophilias.
Despite unfractionated heparin prophylaxis, which was usually 5000 U twice daily, three of 20 women (15 percent) developed antepartum recurrence. his compared with eight of 67 women (12 percent) not given heparin.
125 pregnant women with a single prior VTE. Antepartum hep arin was not given, but anticoagulant therapy was given for 4 to 6 weeks postpartum. Six women had a recurrent venous throm bosis-three antepartum and three postpartum. here were no recurrences in the 44 women without a known thrombophilia or whose prior thrombosis was associated with a temporary risk factor. These findings imply that prophylactic heparin may not be required for these two groups of women. In contrast, and as shown in Table 52-6, women with a prior thrombosis in association with a thrombophilia or in the absence of a tempo postpartum prophylaxis (Connors, 2017).
De Stefano and coworkers (2006) studied 1104 nonpregnant women who had a irst-episode VTE before the age of 40 years. After excluding those with antiphospholipid antibodies, 88 women were identiied who subsequently had a total of 155 pregnancies and who were not given anti thrombotic prophylaxis. There were 19 women (22 percent) who had a subsequent pregnancy-or puerperium-related VTE. Of 20 women whose original thrombosis was associated with a transient risk factornot including pregnancy or oral contraceptive use-there were no recurrences during pregnancy, but two during the puerperium. hese data also suggest that for women with a prior VTE, anti thrombotic prophylaxis during pregnancy could be tailored according to the circumstances of the original event.
It is important to emphasize that VTE may recur despite antithrombotic prophylaxis. Galambosi and associates (2014) studied 270 women during 369 pregnancies who had at least one previous VTE. A total of 28 women (l0.4 percent) sufered a recurrent VTE. Twelve of these recurrences occurred early in pregnancy before the initiation of antithrombotic prophylaxis, and 16 occurred despite prophylactic use of LMWH.