Step 1: Recall the biomedical waste colour code. Each colour maps to a waste category and its treatment route.
Step 2: Red bag or container is for contaminated recyclable waste: tubing, bottles, intravenous sets, catheters, urine bags and blood bags. These go for autoclaving or microwaving and then recycling.
Step 3: Why not the others. Yellow is for human and animal anatomical waste, soiled waste, expired medicines and discarded blood specimens, which are incinerated. Black is for non-infectious general office and ward dry waste. White (translucent) is the puncture-proof container for metal sharps such as needles and blades.
A blood bag is contaminated plastic waste, so it goes in the red bag. Ref: Park's PSM and the Biomedical Waste Management Rules 2016.