This is a very open ended comment but I will take a stab at it.
To build a blood bank management solution, you will need to dabble in supply chain and leverage blockchain to uniquely track each transfusion through the supply chain, to the bank and delivery to the recipient vein.
This is a big and expensive endeavor and I would recommend building such as solution only if you have a paying customer or strategic partner.
For reference, IBM has such a solution for their clients, Canada's blood system is another good example, and various ministries of health also leverage similar systems. Not all countries have such and there is opportunity and need. Research "vein to vein" to learn more.