Questions
2–3 questions per semester paper
Difficulty
Medium
Importance
Core topic for BMLT, MBBS, and Nursing clinical rotations
Overview
Donor selection and screening is the foundational safety protocol in blood banking designed to minimize the risk of Transfusion Transmitted Infections (TTIs). It is a high-yield topic for clinical and laboratory science exams that tests your knowledge of regulatory standards for donor eligibility and mandatory infectious disease testing.
Donor Physical Examination Criteria
Physical screening is the first line of defense to ensure donor health and blood safety. The examiner evaluates vital signs and history to confirm that the donor can tolerate the blood loss and that the blood is safe for the recipient.
- Age: 18 to 65 years
- Weight: Minimum 45 kg (for 350ml) or 50 kg (for 450ml)
- Hemoglobin: Minimum 12.5 g/dL
- Pulse: 60–100 beats/minute (regular)
- Blood Pressure: Systolic 100–140 mmHg, Diastolic 60–90 mmHg
- Temperature: Should not exceed 37.5 degrees Celsius
Mandatory TTI Screening Panels
All blood units must undergo mandatory testing for five specific infectious agents before release for transfusion. These tests ensure the detection of pathogens that can cause severe, long-term health complications in recipients.
- HBsAg: Test for Hepatitis B surface antigen
- HIV: Combined testing for HIV-1 and HIV-2 antibodies/antigens
- HCV: Hepatitis C virus antibody test
- VDRL: Screening for Syphilis (Treponema pallidum)
- Malaria: Peripheral blood smear or rapid antigen test
- NAAT: Nucleic Acid Amplification Testing (mandatory in many advanced centers)
Deferral Guidelines
Donors who fail to meet eligibility criteria must be deferred to prevent harm. Deferrals are categorized as temporary (e.g., post-vaccination or medication) or permanent (e.g., confirmed HIV positivity).
- Permanent deferral: HIV, Hepatitis B, Hepatitis C, or history of IV drug use
- Temporary (12 months): Major surgery, tattoo or piercing, or high-risk sexual contact
- Temporary (4 weeks): Rubella or Hepatitis B vaccine
- Temporary (8 weeks): Following a whole blood donation
- Medication based: Aspirin deferral for platelet apheresis donors
Exam Tip
Always list the five mandatory TTIs (HBsAg, HIV, HCV, Syphilis, and Malaria) as a group; examiners look for this standard panel completeness.
Common Mistakes
- Confusing minimum weight requirements for different blood unit volumes (350ml vs 450ml)
- Failing to mention HIV-1 and HIV-2 specifically during viva or written exams
- Neglecting the difference between permanent and temporary deferral categories
More Revision Notes
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