Can you describe the complete process of preparing donated blood for transfusion, from donor screening and collection through testing, component separation, storage, and cross‑matching?

Blood Donation to Transfusion: Complete Process Overview

The process of making blood available for transfusion involves a systematic sequence of donor screening, collection, testing, processing, storage, and final verification steps designed to maximize recipient safety while protecting donor health.

Donor Screening and Selection

All prospective blood donors must undergo comprehensive screening through medical history interview and physical examination to identify and exclude individuals who pose infectious disease risks to recipients. 1

Pre-Donation Education and Consent

• Donors must receive educational materials explaining HIV transmission risks and agree not to donate if they have potential risk factors for spreading infectious diseases 1
• Prospective donors must sign a consent statement confirming they understand the information provided regarding disease transmission and agree to HIV testing as part of the screening process 1
• The consent must specify that donors will be notified of positive test results according to state statutes and regulations 1

Medical History Interview

• A detailed donor history questionnaire screens for high-risk behaviors including male-to-male sexual contact, injection drug use, exchange of sex for money or drugs, and acquisition of sexually transmitted diseases 1, 2, 3
• The interview identifies recent transfusions, travel to endemic areas, medications, and symptoms suggestive of infectious diseases 2, 4
• All records generated during the interview must be kept confidential 1

Physical Examination

• Donors undergo physical examination with special attention to signs of HIV disease, injection drug use, and general health status 1
• Vital signs and hemoglobin levels are checked to ensure the donor can safely tolerate blood loss 4

Blood Collection

Blood collection must follow strict sterile technique with proper anticoagulant ratios and careful labeling to maintain product quality and traceability. 1

Collection Procedure

• Skin is cleaned thoroughly using chlorhexidine in alcohol or equivalent antiseptic 1
• Blood is collected into packs containing CPD-A1 anticoagulant, with pack size selected to maintain proper anticoagulant-to-blood ratios 1
• A regularly calibrated balance measures the volume of blood drawn 1
• The blood pack is agitated gently throughout collection to mix blood with anticoagulant 1

Immediate Labeling

• During donation, the blood pack is labeled with: surname, first names, date of birth, hospital number, date and time of collection, and responsible medical officer 1
• The label must clearly state "UNTESTED BLOOD: FOR AUTOLOGOUS USE ONLY" until testing is complete 1
• The bleed line is sealed with clips or heat sealer both at the cut end and close to the pack 1

Infectious Disease Testing

All donated blood must be tested for HIV-1, HIV-2, hepatitis B, hepatitis C, and other transfusion-transmitted infections using FDA-licensed assays before release for transfusion. 1, 5

Timing of Sample Collection

• Blood samples for testing should be obtained before any transfusions are administered to the donor to avoid hemodilution causing false-negative results 1
• Samples must be collected as close to the time of blood retrieval as possible 1
• Specimens should not be drawn immediately downstream from an intravenous site to prevent dilution with IV fluids 1

Required Testing Panel

• HIV-1 and HIV-2 antibodies using enzyme immunoassay (EIA) or FDA-licensed combination tests 1
• Hepatitis B surface antigen (HBsAg) to detect active HBV infection 5
• Hepatitis C antibody to identify HCV exposure 5
• Additional testing may include hepatitis B core antibody (anti-HBc), syphilis serology, and other markers as required 5, 6

Testing Algorithm

• Initial EIA test is performed, and if reactive, a retest on the same specimen is conducted 1
• Repeatedly reactive results require confirmatory testing before the unit can be released 1
• All test results are handled confidentially in accordance with federal and state regulations 1

Component Separation and Processing

Whole blood donations are processed into specific components (red cells, platelets, plasma) through centrifugation to maximize therapeutic utility and extend shelf life. 1

Red Cell Preparation

• Whole blood undergoes centrifugation to separate red cells from plasma 1
• Red cells are stored in additive solutions to extend shelf life 1
• Leukocyte reduction is performed to remove white blood cells and reduce transfusion reactions 1

Platelet Preparation

• Platelets are prepared either from whole blood (platelet concentrates) or by apheresis from single donors 1
• The platelet-rich plasma (PRP) method uses initial low-G force centrifugation followed by high-G force spin to concentrate platelets 1
• Apheresis platelets are collected using automated cell separators, yielding the equivalent of 6-9 units of whole blood-derived platelets 1
• Each apheresis product must contain at least 3×10¹¹ platelets and typically has a volume of approximately 200 mL 1

Processing Requirements

• Cord blood (when collected) should be processed and frozen within 48 hours of collection 1
• Standardized freezing and storage conditions must be followed according to accreditation standards 1
• Segments are attached to blood products for testing and confirmation of identity 1

Storage and Inventory Management

Blood components must be stored under specific temperature conditions with strict expiration monitoring to maintain viability and prevent bacterial growth. 1

Storage Conditions

• Red cell units are stored in refrigerators at 1-6°C 1
• Platelets are stored at room temperature (20-24°C) with continuous agitation to prevent aggregation 1
• Frozen components (plasma, cryoprecipitate) are stored at -18°C or colder 1
• Cord blood units are stored under liquid nitrogen or at equivalent temperatures 1

Expiration and Quality Control

• Red cell transfusions must be completed within 4 hours of removal from the blood fridge 1
• Blood components are visually inspected for leakage, discoloration, clots, or clumps before issue 1
• Expiry dates and times are clearly marked and verified before release 1

Cross-Matching and Compatibility Testing

Before transfusion, recipient blood samples are tested against donor units to ensure ABO/Rh compatibility and detect unexpected antibodies that could cause hemolytic reactions. 1, 7

Pre-Transfusion Testing

• Recipient blood type (ABO and Rh) is determined 1
• Antibody screening identifies unexpected red cell antibodies in the recipient 1
• Cross-matching tests recipient serum against donor red cells to detect incompatibility 1
• For platelets, ABO typing is performed but cross-matching is not necessary due to low red cell content 1

Sample Requirements

• Blood samples must be properly labeled with four core identifiers: first name, last name, date of birth, and patient identification number 1, 7
• Samples should be recent (typically within 72 hours of transfusion) to detect newly formed antibodies 1

Final Verification and Administration

Administering the correct blood component to the correct patient requires meticulous bedside verification using a standardized checking process—this is the most critical safety step in the entire transfusion process. 1, 7

Bedside Verification Process

• The patient must be positively identified using an identification wristband containing four core identifiers 1, 7
• Immediately before transfusion, check the component next to the patient against the prescription 1, 7
• Verify the four core identifiers on the compatibility label match the patient's identification 1, 7
• Confirm the compatibility label has the same blood group and 14-digit component donation number as the sticker on the blood component 1, 7
• Visually inspect the blood component for leakage, discoloration, clots, or clumps 1, 7
• Check the expiry date and time 1, 7

Administration Guidelines

• Use blood administration sets equipped with inline filters to trap micro-aggregates 7, 8
• Never pressurize blood transfusion bags, as this significantly increases air embolism risk 8
• Establish large-bore intravenous access (ideally ≥18 gauge) for adequate flow 7
• Monitor vital signs at baseline (within 60 minutes before starting), 15 minutes after start, at completion of each unit, and 15 minutes after transfusion ends 7

Documentation and Traceability

• 100% traceability of all blood components is a legal requirement, with records retained for 30 years 1, 7
• Document the type, volume, donation number, blood group, and expiry date/time in the patient record 7
• Record the total number of units and cumulative volume transfused in operative notes 7
• If allogeneic blood was given, clearly state the clinical justification 7

Post-Transfusion Requirements

• Inform patients before discharge that they received blood components and are no longer eligible as blood donors 1, 7
• Notify the patient's general practitioner of the transfusion 1, 7
• Report any serious adverse events to the hospital transfusion committee and national reporting system 7

Critical Safety Pitfalls to Avoid

• Never perform identity verification away from the bedside or in advance—bedside verification is the single most effective safeguard against ABO incompatibility errors, which represent the most serious transfusion complication 1, 7
• Do not use posttransfusion/infusion specimens for donor testing without assessing for hemodilution, as this can cause false-negative infectious disease results 1
• Avoid rapid transfusion in patients with cardiac or renal comorbidities to prevent transfusion-associated circulatory overload (TACO) 7
• Do not transfer blood without the transfusion laboratory's knowledge, as this breaks the chain of custody and traceability 7
• In patients with right-to-left cardiac shunts, absolute exclusion of all air bubbles is mandatory to prevent paradoxical air embolism 8