Sickle cell disease (SCD) is one of the most common inherited diseases worldwide and exhibits highest frequency in people of African descent. Patients with SCD currently have few treatment options, with hydroxyurea being the only medication approved to reduce the frequency of vaso-occlusive crisis (VOC) and prevent other SCD complications such as acute chest syndrome. Once patients develop VOC, hospitalizations aim to alleviate pain; no specific therapy is currently available to otherwise affect the course of the VOC. However, there has been increasing interest in the role of coagulation in the pathogenesis of SCD. The investigators hypothesize that low dose anticoagulant therapy, such as prophylactic dose low-molecular-weight heparin (LMWH), could be a novel way to ameliorate the vaso-occlusive process and thereby hasten the resolution of pain.