Blood transfusions are very important in some severe medical procedures and emergencies. It is highly critical that the right blood type and disease-free blood is given to the patient. This is why giving and receiving blood is not as easy as it seems.

Blood donors must be volunteers and should be unpaid. Usually, the first people to be asked if they can donate blood are the immediate family members of the patient as blood types are usually a match.

Medical professionals must make sure that the blood transfusion will be useful to the recipient and it will not affect the health of the donor.

To be a donor, it is not enough to have the same blood type as the recipient. The donor should be healthy. This will be determined by the answers the donor will give during the preliminary interview. Questions will cover habits of the donor, weight, adequate age, and other pertinent information. Standards vary in each country. Units of blood before transfusion are also screened for infectious diseases.