20899
BACKGROUND : In patients bitten by North American rattlesnakes and treated with Crotalidae Polyvalent Immune Fab ( Ovine ) ( FabAV ) , late hematologic abnormalities - persistent , recurrent , or late , new onset of hypofibrinogenemia , prolonged PT / INR , prolonged PTT , and / or thrombocytopenia beyond 48 h post - envenomation - are common , difficult to manage , and may result in morbidity and mortality are common , difficult to manage , and may result in morbidity and mortality .
 None
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 None