Unless you plan on giving yourself a transfusion with the universal donor type (O-), you need to test your blood first. An incorrect blood type transfusion will make you infected.
- Find a Blood Transfusion Kit and Right click on it.
- On the right, click on the water and put a drop on each of the types / circles
- On the left, click on the blood sample and put a drop on each of the types / circles
- The sample that coagulates is your blood type.