Heparin Resistance due to an Acquired Antithrombin Deficiency in a Patient With Sickle Cell Disease During a Pregnancy Complicated by Bilateral Pulmonary Emboli: A Case Report.

We report a 31-year-old woman with sickle beta thalassemia zero who presented at 21 weeks gestational age with multiple bilateral pulmonary emboli and no hemodynamic instability. Acquired antithrombin deficiency was suspected due to a refractory response to therapeutic anticoagulation with enoxaparin, unfractionated heparin, and fondaparinux, and a reduced antithrombin antigen level. At 26 4/7 weeks, she developed signs concerning for increased pulmonary clot burden. To avoid the use of alternative anticoagulants that may cross the placenta and impact the fetus, a planned cesarean delivery was performed without complication at 27 weeks gestation. Both mother and child experienced successful long-term outcomes.