Blood donation provides a lifeline for countless patients needing transfusions for surgeries, emergencies, and chronic conditions. Ensuring blood supply safety is paramount, involving thorough checks and laboratory tests on every donation. These stringent measures protect both donor and recipient health.
Donor Eligibility Checks
Before donating blood, a comprehensive screening determines eligibility. This assessment begins with a detailed health questionnaire covering medical history, recent travel, medications, and potential risk factors for infectious diseases. These questions identify conditions or exposures that could pose a risk to recipients or donors.
Following the questionnaire, several physical checks are performed. The donor’s temperature, blood pressure, and pulse are measured to ensure healthy ranges for donation. A check of the donor’s hemoglobin level, an oxygen-carrying protein in red blood cells, is also performed via a finger-prick. This test confirms sufficient iron stores for safe donation, preventing anemia; women typically need at least 12.5 g/dL, while men require 13.0 g/dL. If hemoglobin is too low, donation is deferred to allow iron levels to recover.
Testing Donated Blood
Once blood is collected, test tubes from each donation are sent for extensive laboratory analysis. This testing is mandated by regulatory bodies like the U.S. Food and Drug Administration (FDA) to prevent infectious disease transmission and ensure transfusion compatibility. All tests must yield negative results before the blood is deemed suitable for use.
Infectious disease screening is a primary focus. Every unit is tested for pathogens including Human Immunodeficiency Virus (HIV-1 and HIV-2), Hepatitis B Virus (HBV), Hepatitis C Virus (HCV), and Syphilis, detecting the virus or antibodies. Nucleic Acid Testing (NAT) for HIV, HBV, and HCV detects viral genetic material earlier than antibody tests, significantly reducing the “window period.” Tests for West Nile Virus (WNV) and Chagas disease (caused by Trypanosoma cruzi) are also performed. While Zika virus testing was previously universal in the U.S., the FDA determined in 2021 it is no longer a “relevant transfusion-transmitted infection,” allowing routine testing to cease.
Beyond infectious diseases, blood type identification is performed on every donation. This involves determining the ABO blood group (A, B, AB, or O) and the Rh factor (positive or negative). This ensures patients receive compatible blood, preventing potentially life-threatening immune reactions. Screening for red cell antibodies, which can cause transfusion reactions, is also a standard part of the testing process.
Understanding Test Results
After comprehensive laboratory testing, results dictate the fate of the donated blood and donor interaction. If all tests for infectious disease markers are negative, the blood is considered safe for transfusion and proceeds to processing and storage. Red blood cells can be refrigerated for up to 42 days, platelets stored at room temperature for a shorter period, and plasma frozen for up to a year.
If a test result is positive for an infectious disease marker, the donated blood unit is immediately quarantined and not used for transfusion. Donors are confidentially notified of any positive results, typically via registered letter or telephone for certain infections. This notification is important for the donor’s health, advising them to seek medical follow-up and counseling. Public health authorities are also informed of confirmed positive results, as required by law, to help monitor and control disease spread. Donor privacy and confidentiality are strictly maintained.