Overview
Blood Transfusion services form an essential part of the health care system. The main aim of a Blood Transfusion centre is to provide safe blood and blood products, free of pathogenic organisms, to patients who need them — and this begins with the recruitment of healthy donors.
Blood donation forms the cornerstone of a blood transfusion service. An effective programme for donor selection and screening ensures the overall safety of the entire transfusion process, protecting both the donor and the eventual recipient.
Learning Objectives
After this lesson you will be able to…- Enlist the types of blood donors
- Explain the criteria for selection of donors
- Describe the conditions for deferring blood donors
- List the laboratory tests performed prior to blood donation
Clinical Story
Why This MattersA young man arrives at a blood donation camp wanting to donate blood for the first time. Before any needle touches his arm, the blood bank technologist must carefully screen him — taking a detailed history, performing a physical examination, and checking his hemoglobin — to ensure both his own safety and that of the eventual recipient. A single overlooked detail in donor screening could transmit a serious infection or harm the donor himself.
Core Concepts
There are four types of donors: Voluntary/unpaid donors who donate of their own free will without monetary benefit; Paid/professional donors who receive payment; Replacement donors who are friends or relatives of the patient replacing the unit issued; and Autologous donors who donate blood for their own future use. The WHO recommends the donor base should mostly be voluntary, with reliance on replacement and professional donors being phased out.
Donor screening has four components: (1) Donor registration — recording donation date/time, name, parent/spouse name, age, gender, occupation, address, and blood group if known, retained for 10 years; (2) Medical history — taken by a trained person, referring abnormal findings to the physician; (3) Physical examination — to confirm fitness; (4) Laboratory testing — including hemoglobin estimation and ABO/Rh grouping.
Donors must meet: Age 18–65 years; Weight >45kg (donate 350ml) or >60kg (donate 450ml); Normal blood pressure; Pulse 80–100/min, regular; Afebrile (body temp not >37.5°C); Venipuncture site free of lesions; normal systemic examination; minimum 12-week interval between donations.
Donors are screened for high-risk behaviours and symptoms: homosexual males with multiple male partners, individuals with multiple sexual partners, commercial sex workers, intravenous drug abusers, professional paid donors, and symptoms suggestive of HIV infection in the last 6 months (unexpected weight loss >10%, night sweats, unexplained fever >99°F for over 10 days, lymphadenopathy, persistent diarrhea, persistent cough, oral white patches).
Laboratory Principle
Donor screening operates on the principle of risk stratification — combining a structured medical history, a focused physical examination, and targeted laboratory testing (hemoglobin and ABO/Rh grouping) to identify donors who could either be harmed by donation or whose blood could harm a recipient. This multi-layered approach minimizes the "window period" risk of transfusion-transmitted infections and protects donor wellbeing.
Equipment Required
Reagents & Materials
| Reagent / Material | Concentration / Grade | Purpose | Storage |
|---|---|---|---|
| ABO/Rh antisera | Monoclonal, as per manufacturer | Blood grouping of donor sample | Refrigerated when not in use |
| Drabkin's solution / Sahli's reagent | As per chosen Hb method | Pre-donation hemoglobin screening | As per reagent requirements |
Step-by-Step Procedure
Record donation date/time, name, father's/husband's name, age, gender, occupation, address with telephone numbers, and blood group if known. These records are maintained for 10 years.
A qualified trained person takes a detailed medical history, enquiring about high-risk activities, symptoms suggestive of infection, and conditions causing temporary or permanent deferral. Refer abnormal findings to the physician.
Check age (18–65 years), weight, blood pressure, pulse (80–100/min, regular), temperature (afebrile), venipuncture site, and systemic examination of heart, lungs and abdomen.
Estimate hemoglobin (must be >12.5 g/dl, or hematocrit >38% if Hb not available) and perform ABO and Rh grouping on every donor.
Based on history and examination, classify the donor as Accepted, Temporarily deferred (asked to return after a specified period), or Permanently deferred. Record all results on the donor form.
Flow Diagram
Quality Control
Every donor record must be carefully reviewed for completeness; standardized criteria for deferral periods (e.g., 1 year after major surgery, 3 days after dental manipulation) must be consistently applied by all screening staff to ensure no donor slips through without proper evaluation.
Donor screening protocols should align with national blood transfusion service guidelines and WHO recommendations, and should be periodically audited for compliance with deferral criteria and documentation standards.
Reference Values
Donor Eligibility Criteria⚠️ Reference ranges may vary between laboratories. Always apply your laboratory's established reference intervals.
Clinical Interpretation
| Finding | Possible Significance | Action / Follow-up |
|---|---|---|
| Hb > 12.5 g/dl, no deferral criteria | Donor fit for donation | Proceed with blood collection |
| Minor surgery, dental manipulation, vaccination | Temporary deferral required | Defer for specified period (3 days to 1 year), reassess at next visit |
| HIV antibody positive, Hepatitis B/C infection, malignancy | Permanent deferral required | Cannot be accepted as donor under any circumstances; counsel and refer appropriately |
Common Errors & How to Avoid Them
Cause: Rushed screening or failure to ask about high-risk activities and recent medications can miss deferral indications.
Prevention: Always use a standardized history checklist and allow adequate time for confidential, private questioning.
Cause: Staff unfamiliarity with the exact deferral periods (e.g., 3 days for oral antibiotics vs. 5 years for tuberculosis) can lead to premature acceptance or unnecessary rejection.
Prevention: Keep an updated deferral reference chart at the screening desk for quick consultation.
Cause: Donors on salicylates (aspirin) within the last 72 hours should not donate for platelet rich plasma/platelet concentrate.
Prevention: Specifically ask about recent aspirin use when platelet donation is intended.
Laboratory Tips from the Bench
Some vaccinations (Tetanus, Diphtheria, Typhoid, Prophylactic Hepatitis B) do NOT require donor deferral — know this list to avoid unnecessarily turning away eligible donors.
Always counsel donors about the significance of test results before donation, and assure them of confidentiality — this builds trust and encourages repeat voluntary donation.
Remember "RHM-L" for the four screening steps: Registration → History → Medical (physical) examination → Laboratory testing.
Important Notes
The World Health Organization recommends that the donor base should mostly be voluntary, with reliance on replacement and professional donors phased out, as voluntary donors statistically carry the lowest risk of transfusion-transmitted infections.
Donors must be assured that all information disclosed during screening, including test results, will be kept strictly confidential, encouraging honest disclosure of risk factors.
Interactive Quiz
Test Your KnowledgeFlashcards
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Clinical Case Study
Apply Your KnowledgeMr. Kumar arrives at a college blood donation drive. He is healthy with no symptoms, but mentions he had a tooth extraction 10 days ago and is currently taking an oral antibiotic course that finished 2 days ago.
His hemoglobin, weight, blood pressure, and pulse all meet donation criteria. However, dental surgery (extraction) requires a 1-month deferral period, not the 3-day period for minor dental manipulation. He should be deferred and asked to return after completing the full deferral period.
- →Dental surgery (extraction) requires 1 month deferral, while minor dental manipulation (cleaning) requires only 3 days
- →Even with all physical parameters normal, history-based deferral criteria must always be checked
- →Recently completed antibiotic course also requires a 3-day deferral after the last dose
Frequently Asked Questions
Paid donors have a higher statistical risk of concealing high-risk behaviour or illness in order to receive payment, increasing the chance of transfusion-transmitted infections. WHO therefore recommends phasing out reliance on paid and replacement donors in favour of voluntary, unpaid donors.
Tetanus, Diphtheria, Typhoid, and Prophylactic Hepatitis B vaccinations do not require any deferral period. However, live vaccines like polio, measles, mumps, and yellow fever require a 2-week deferral, and Rubella requires 4 weeks.
Yes, if hemoglobin estimation is not available, hematocrit can be used as an alternative screening parameter, and must be greater than 38% for the donor to be considered fit for donation.
Quick Revision
10-Minute ReviewKey Takeaways
- Four types of donors exist, with voluntary unpaid donors being the WHO-preferred type
- Donor screening involves registration, medical history, physical examination, and laboratory tests
- Physical examination criteria include age, weight, blood pressure, pulse, and temperature
- Causes of deferral may be permanent (e.g., HIV+, malignancy) or temporary (e.g., surgery, pregnancy)
- Minimum hemoglobin for donation is 12.5 g/dl, with a 12-week donation interval
- ABO and Rh grouping is mandatory laboratory testing on every donor
Competency Checklist
Track Your MasteryReferences
- World Health Organisation. Blood Donor Selection: Guidelines on Assessing Donor Suitability for Blood Donation.
- AABB Technical Manual. 19th ed.
- NIOS Vocational Course — Hematology and Blood Bank Technique, Lesson 5.