Introduction Pregnancy-induced hypercoagulable states present an anticoagulation management challenge in patients with mechanical prosthetic valves (PHV). In pregnant patients a thrombosed mechanical PHV presents a high risk of morbidity and mortality for both mother and fetus. We present a complex case of a pregnant patient with a thrombosed PHV. Methods N/A Results N/A Discussion A 32 y.o. female at 17 weeks gestation with rheumatic heart disease, s/p mechanical mitral (MVR) and aortic (AVR) valve replacement in 2002, was transferred for management of her thrombosed mitral PHV. The patient had been switched from warfarin to therapeutic low molecular weight heparin (LMWH) pre-partum. She first noticed increased shortness of breath at 10-11 weeks gestation and serial TTE revealed progressively increasing MV pressure gradients due to an immobile mitral PHV disk. Based on concerns that continued pregnancy would complicate maternal outcome and fetal age, a multi-specialty suggestion was made and pregnancy was terminated at our institution. The patient underwent a reoperation aimed at replacing the thrombosed mitral PHV. Intraoperatively, TEE showed that the mitral PHV disks had unrestricted motion and gradients decreased (from 9 mmHg to 3 mmHg). Subsequently, the patient underwent a thrombectomy of the mechanical mitral PHV. The anticoagulation management of pregnant women with mechanical PHV is challenging. The hypercoagulable state in pregnancy should be balanced by anticoagulation with its associated risks of teratogenicity and bleeding. The treatment options include thrombolysis, thrombectomy and valve replacement. The 2014 ACC/AHA guidelines provide guidance, based on class B or Class C evidence. The decision to switch the patient from warfarin to LMWH is controversial due to current ACC/AHA guidelines to continue warfarin up to 5 mg during pregnancy. Pregnancy termination is questionable due to multiple case reports showing the ability to continue pregnancy with thrombolysis, as long as the patient does not develop CHF. At the end, this patient's thrombosis resolved with heparin, and surgical thrombectomy and pregnancy termination could have been avoided. On the other hand, surgical thrombectomy, exposure to CPB and stress of cardiac surgery leads to ∼50% risk of miscarriage.