Before donated blood can be used for transfusions, it undergoes a series of stringent tests. These evaluations ensure the safety and compatibility of the blood supply, protecting both the recipient and the donor. The comprehensive testing process safeguards public health.
Why Blood Donations Undergo Rigorous Testing
Blood testing serves dual purposes: protecting the recipient’s health and ensuring the donor’s well-being. Patients receiving transfusions are often susceptible to infections or adverse reactions. Screening minimizes the risk of transmitting infectious agents.
Beyond protecting recipients, testing also verifies the donor’s health and eligibility. Checking hemoglobin levels before donation ensures the donor can safely give blood without risking anemia. This approach establishes a safe and reliable blood supply.
Comprehensive Screening for Infectious Diseases
Blood testing focuses on identifying infectious diseases that could be transmitted through transfusion. Donated blood is routinely screened for Human Immunodeficiency Virus (HIV-1 and HIV-2) using antibody tests and Nucleic Acid Testing (NAT) for early detection of viral RNA. Hepatitis B Virus (HBV) is detected through tests for Hepatitis B surface antigen (HBsAg), antibody to Hepatitis B core antigen (anti-HBc), and HBV DNA using NAT. Hepatitis C Virus (HCV) is screened for using antibody tests (anti-HCV) and NAT for HCV RNA.
Syphilis, caused by Treponema pallidum, is a mandatory screening test, detected by identifying specific antibodies. Other pathogens screened include West Nile Virus (WNV) via NAT for viral RNA, and in some regions, Zika Virus (ZIKV) RNA and Trypanosoma cruzi (Chagas disease). Human T-lymphotropic virus (HTLV-I/II) antibodies are also routinely tested. NAT can detect viral genetic material earlier than antibody tests, shortening the “window period” when an infection might be present but undetectable.
Determining Blood Type and Other Donor Health Markers
Beyond infectious disease screening, every blood donation undergoes tests to determine its compatibility and donor health. Blood grouping identifies the ABO type (A, B, AB, or O) and the Rh factor (positive or negative). Accurate ABO and Rh typing is fundamental for safe transfusions, as incompatible blood can lead to severe reactions.
Pre-donation testing also includes a check of the donor’s hemoglobin and hematocrit levels. Hemoglobin is a protein in red blood cells that carries oxygen, while hematocrit measures the percentage of red blood cells. These tests ensure the donor has sufficient red blood cells, preventing post-donation anemia. Acceptable hemoglobin levels for donation are a minimum of 12.5 g/dL for women and 13.0 g/dL for men.
Understanding Test Results and Donor Notification
Once tests are complete, the results determine the donated unit’s use. If all infectious disease tests are negative, the blood is processed for transfusion or manufacturing into blood products. This blood is then released for patient use.
If an infectious disease test yields a positive result, the donated unit is not used. The donor is confidentially notified of the finding and provided with information and counseling. This notification often includes referral for further medical evaluation. Donors with confirmed positive results are deferred from future donations, either temporarily or permanently. Confidentiality of all donor information and test results is maintained.