Overview
Collection of blood from donors is one of the most important functions of the blood bank. Failure to follow approved procedures can lead to severe and potentially fatal consequences in both the recipient and the donor.
This lesson covers the full process — from pre-donation counseling through phlebotomy technique, labeling, storage, and recognition and management of donor reactions — ensuring a safe, aseptic, and well-documented blood collection process.
Learning Objectives
After this lesson you will be able to…- Describe the procedure of collection of blood from donors as per recommended guidelines
- Discuss the care and storage of the collected blood
- Explain the care of donors after donation of blood
- List the tests performed on donor blood
Clinical Story
Why This MattersA donor is comfortably seated and ready for blood collection at a hospital blood bank. As the phlebotomist begins the venipuncture, the donor suddenly becomes pale, sweaty, and dizzy — a vasovagal reaction. The technologist must instantly recognize this, lower the donor's head, raise the legs, and provide reassurance, while continuing to safely manage the collected blood bag. This lesson prepares you for exactly such real-time decisions.
Core Concepts
The donor must be given written or verbal information about their rights, the procedure of donation, and the tests that will be performed on the collected unit. They must sign the donor form indicating informed consent and agreement to testing for infectious agents. Counseling must be provided in privacy before donation, explaining the possible consequences of learning test results.
Blood collection bags are closed-system PVC plastic bags (single, double, triple, or quadruple bags), used for collecting 350ml or 450ml of blood. They contain CPDA-1 (citrate phosphate dextrose-adenine) anticoagulant — 49ml for 350ml of blood and 63ml for 450ml. The shelf life of blood collected in CPDA-1 is 35 days.
Each blood group is designated a colored sticker: Pink for A, Yellow for B, Blue for O, White for AB. The bag must record donor number, date of collection, date of expiry, blood group, and infection screening status. Blood is stored at 2–6°C with an inbuilt alarm system; if platelets are to be harvested, the bag is kept at 20–24°C until platelet separation.
Most donors tolerate donation well, but reactions can occur — from mild vasovagal symptoms (faintness, dizziness, weakness, sweating, pallor) to hematoma formation, nausea/vomiting, muscular spasm, convulsions, and rarely, sudden cardiac arrest. All reactions must be promptly recognized, managed per protocol, and documented.
Laboratory Principle
Blood collection relies on maintaining a closed, sterile, anticoagulated system from venipuncture through to storage. CPDA-1 anticoagulant prevents clotting and preserves red cell viability and ATP levels for up to 35 days. Maintaining the cold chain (2–6°C) slows red cell metabolism and bacterial growth, while the closed-bag system minimizes contamination risk throughout collection, processing, and storage.
Equipment Required
Reagents & Materials
| Reagent / Material | Concentration / Grade | Purpose | Storage |
|---|---|---|---|
| CPDA-1 Anticoagulant | 49ml (350ml bag) / 63ml (450ml bag) | Prevents clotting, preserves red cells for 35 days | Pre-filled in sterile collection bag |
| Spirit and Iodine | Standard antiseptic grade | Skin disinfection before venipuncture | Room temperature |
| Sterile cotton swabs, band-aid | Medical grade | Post-venipuncture site care | Sterile packaging |
Step-by-Step Procedure
Wash hands and wear sterile gloves. Inspect the bag for leaks or damage. Identify the donor and confirm the bag number matches the donor form. Write date of collection and expiry on the bag.
Choose a large, firm vein in the antecubital area. Apply the sphygmomanometer cuff to 50-60mm Hg to identify the vein, then deflate and clean 4-5cm of skin in a circular centrifugal manner with spirit, iodine, then spirit again. Allow to dry for 30 seconds.
Re-inflate the cuff to maintain 50-60mm Hg, remove the needle cap, and insert into the vein. Ask the donor to open and close their fist during collection to maintain blood flow.
Mix blood and anticoagulant periodically (manually or by automated mixer). Monitor volume using a balance or collection monitor scale (350ml blood weighs 367g; 450ml weighs 472g). Do not leave the donor unattended; collection takes 8-10 minutes.
Clamp the tubing with a plastic clip, deflate the cuff, apply pressure with a sterile swab, and let the donor rest 5-10 minutes. Take the bag to the processing table, transfer blood to pilot tubes for grouping and infection screening, strip and mix the bag, then refrigerate at 2-6°C.
Flow Diagram
Quality Control
Always inspect collection bags for leaks, damage, or particulate matter in the anticoagulant before use. Blood bank refrigerators must have continuous temperature monitoring with an inbuilt alarm to alert staff if the temperature rises above range, ensuring the cold chain is never broken.
All collected units undergo mandatory screening for transfusion transmitted infections (HBsAg, HCV, HIV-1/2, syphilis, malaria) and ABO/Rh confirmation before release, in line with national blood transfusion service standards.
Reference Values
Key Collection Parameters⚠️ Reference ranges may vary between laboratories. Always apply your laboratory's established reference intervals.
Clinical Interpretation
| Finding | Possible Significance | Action / Follow-up |
|---|---|---|
| Donor pale, sweaty, dizzy during/after donation | Vasovagal reaction | Lower head, raise legs, loosen clothing, monitor vitals, reassure donor |
| Swelling at venipuncture site | Hematoma formation | Apply firm pressure; ice for 5 minutes if needed |
| Convulsions during donation | Medical emergency | Inform blood bank physician immediately; prevent self-injury; seek urgent assistance |
Common Errors & How to Avoid Them
Cause: Inadequate or incorrect (non-centrifugal) cleaning technique increases risk of bacterial contamination of the unit.
Prevention: Always clean in a circular, centrifugal manner — starting at the venipuncture site and moving outward — with spirit, iodine, then spirit again; avoid touching the cleaned area afterward.
Cause: Donor reactions (vasovagal, hematoma, convulsions) can occur suddenly during the 8-10 minute collection.
Prevention: Never leave the donor unattended during the entire collection procedure.
Cause: Mismatched bag and pilot tube numbers can lead to mislabeled units and dangerous transfusion errors.
Prevention: Always recheck that the number on pilot tubes matches the number on the blood bag before sealing.
Laboratory Tips from the Bench
Provide light refreshment to every donor after the rest period — this helps prevent post-donation hypoglycemia-related faintness and improves the donor's overall experience, encouraging repeat voluntary donation.
Always instruct donors to avoid smoking or driving for 30 minutes, avoid alcohol for 24 hours, and avoid strenuous exercise for 24 hours after donation — clear post-donation instructions reduce complication rates.
Remember "CPDA-1, 35 days" as a fixed pair — Citrate Phosphate Dextrose Adenine is the anticoagulant that extends blood shelf life to exactly 35 days.
Important Notes
One ml of blood weighs 1.05g. Thus, 350ml of blood weighs 367g and 450ml weighs 472g — this conversion is essential for accurately monitoring collected blood volume on a balance scale.
Pink = Group A, Yellow = Group B, Blue = Group O, White = Group AB. This color-coding system enables rapid visual identification of blood group during emergency situations.
Interactive Quiz
Test Your KnowledgeFlashcards
Tap to flipClick or tap any card to reveal the answer. Use arrow keys to navigate in single-card mode.
Clinical Case Study
Apply Your KnowledgeMr. Singh cleared donor screening and donation began smoothly. At minute 6 of collection, he suddenly reports feeling lightheaded, appears pale, and starts sweating profusely. His pulse is noted to be rapid.
The combination of pallor, sweating, and rapid weak pulse during donation is classic for a vasovagal reaction. The technologist should immediately stop collection if not already complete, clamp the tubing, lower the donor's head with legs raised, loosen clothing, and monitor vitals closely until recovery.
- →Never leave the donor unattended; reactions can occur even mid-collection
- →Position changes (head low, legs raised) are the cornerstone of vasovagal reaction management
- →All donor reactions must be documented per blood bank protocol, even mild ones
Frequently Asked Questions
Opening and closing the fist promotes muscle contraction, which helps maintain venous blood flow and speeds up collection, reducing the time the needle remains in place and minimizing donor discomfort.
Every unit undergoes ABO grouping, Rh grouping, and screening for transfusion transmitted infections including Hepatitis B virus (HBsAg), Hepatitis C virus (HCV), HIV-1/2, syphilis, and malaria.
Blood donation temporarily reduces blood volume and oxygen-carrying capacity. For pilots, who require optimal alertness and physiological reserve at altitude, this temporary reduction could affect performance and safety, hence the 24-hour flying restriction.
Quick Revision
10-Minute ReviewKey Takeaways
- Blood collection requires informed consent, careful donor identification, and aseptic technique
- CPDA-1 anticoagulant in closed PVC bags preserves blood for 35 days at 2-6°C
- Proper venipuncture site preparation prevents bacterial contamination
- Color-coded labeling enables rapid blood group identification
- Donors must be monitored throughout and after collection for reactions
- All collected units are screened for ABO/Rh grouping and transfusion-transmitted infections
Competency Checklist
Track Your MasteryReferences
- AABB Technical Manual. 19th ed.
- World Health Organisation. Blood Donor Selection and Blood Collection Guidelines.
- NIOS Vocational Course — Hematology and Blood Bank Technique, Lesson 6.