CBC with peripheral smear (anemia, microspherocytes, thrombocytopenia are suggestive findings)
Microangiopathic hemolytic anemia produces schistocytes
LDH (elevated)
Haptoglobin (decreased)
Reticulocyte count (appropriate)
Urinalysis (hemoglobinuria)
Creatinine (possibly elevated)
LFTs (increased bilirubin)
PT/PTT/INR (normal; differentiates from DIC)
Urine pregnancy (significant association between pregnancy and<unk> 
Gel electrophoresis
Microangiopathic hemolytic anemia produces schistocytes
Thrombotic thrombocytopenic purpura
Other MAHAs 
Immune thrombocytopenic purpura
ITP
Disseminated intravascular coagulation
Sepsis
Heparin-Induced Thrombocytopenia 
SLE