Final answer:
Patients may need medical clearance and a blood transfusion at a hemoglobin level of 5 to 9 g/100 ml in weaned infants and young children. Matching the ABO blood type is crucial to prevent potentially lethal reactions. Medical laboratories and hemovigilance systems enhance safety by tracking transfusion information and preventing HTRs.
Step-by-step explanation:
Patients may require medical clearance and may also indicate a need for a blood transfusion at a hemoglobin level of 5 to 9 g/100 ml of blood, which is observed in weaned infants and young children. At this level, children exhibit symptoms such as dullness, inactivity, pallor of the skin, poor appetite, and delayed growth and development.
When a patient needs a blood transfusion, it is crucial to match the ABO blood type to avoid a potentially life-threatening reaction called hemolytic transfusion reaction (HTR). If an incompatible blood type is transfused, it can trigger a strong immune response that leads to the destruction of red blood cells.
Medical laboratories and hemovigilance systems play a significant role in ensuring safe transfusions. These systems track transfusion information, identify HTRs, and provide valuable data to prevent such occurrences in the future.