This is a test of commonsense. Complete the next sentence:

How to remove blood stains from a mattress
Strip the bed.
To remove any stain from the mattress, you'll have to be able to access the mattress directly. Remove pillows, comforters, duvets, sheets, and anything else from the bed that's covering the mattress.
Set pillows and decorative items aside so you don't trip on them while you're working. Pre-treat sheets, pillow cases, comforters, and other washable bedding with an enzyme cleaner or stain remover if there's blood on them.