his agent should be considered for the initial treatment of thromboembolism and in situations in which delivery, surgery, or thrombolysis may be necessary (American College of Obstetricians and Gynecologists, 20 17b). U nfractionated heparin can be administered by one of two alternatives: (I) initial intravenous therapy followed by adjusted-dose subcutaneous UFH given every 12 hours; or (2) twice-daily, adjusted-dose subcutaneous UFH with doses adjusted to prolong the activated partial thromboplastin time (aPTT) into the therapeutic range 6 hours postinjection (Bates, 2012). As shown in Table 52-5, the therapeutic dose for subcutaneous UFH is usually 10,000 units or more every 12 hours.
For intravenous therapy, several protocols are acceptable. In general, if UFH is used, it is initiated with a bolus intravenous dose of70 to 100 U/kg, which is 5000 to 10,000 U. This is followed by continuous intravenous infusions beginning at
TABLE 52-5. Anticoagulation Regimen Definitions
Prophylactic LMWHa Enoxaparin,n40 mg SC once daily Dalteparin, 5,000 units SC once daily Tinzaparin, 4,500 units SC once daily
Therapeutic LMWHb Enoxaparin, 1 mg/kg every 12 hours Dalteparin, 200 units/kg once daily Tinzaparin, 175 units/kg once daily Dalteparin, 100 units/kg every 12 hours
May target an anti-Xa level in the therapeutic range of 0.6-1.0 units/mL for twice daily regimen; slightly higher doses may be needed for a once-daily regimen.
Minidose prophylactic UFH UFH, 5,000 units SC every 12 hours Prophylactic UFH UFH, 5,000-10,000 units SC every 12 hours
UFH, 5,000-7,500 units SC every 12 hours in first trimester
UFH 7,500-10,000 units SC every 12 hours in the second trimester
UFH, 10,000 units SC every 12 hours in the third trimester, unless the aPTI is elevated
Therapeutic UFHb UFH, 10,000 units or more SC every 12 hours in doses adjusted to target aPTI in the therapeutic range (1n.5-2.5) 6 hours after injection
Postpartum anticoagulation Prophylactic LMWH/UFH for 4-6 weeks or vitamin K antagonists for 4-6 weeks with a target INR of 2.0-3.0, with initial UFH or LMWH therapy overlap until the INR is 2.0 or more for
Surveillance Clinical vigilance and appropriate objective investigation of women symptoms suspicious of deep-vein thrombosis or pulmonary embolism
Abbreviations: aPTI, activated partial thromboplastin time; INR, international normalized ratio; LMWH, low-molecular-weight heparin; SC, subcutaneously; UFH, unfractionated heparin.
aAlthough at extremes of body weight, modification of dose may be required. bAlso referred to as weight adjusted, full treatment dose.
Reproduced with permission from American College of Obstetricians and Gynecologists Women's Health Care Physicians:
Bulletin No. 138: Inherited thrombophilias in pregnancy, Obstet Gynecol. 2013 Sep;122(3):706-717.