11.1 Donor Selection, Physical Examination, Screening, and Mandatory Infectious Marker Testing

Donor Selection, Physical Examination, Screening, and Mandatory Infectious Marker Testing

Blood donor qualification serves as the first and most critical defense against transfusion-transmitted morbidity. In immunohematology, the donor qualification pathway integrates two equally vital mandates: protecting donor health from the physiological stresses of phlebotomy and safeguarding the recipient from infectious, immunological, or toxic complications. For medical technologists preparing for the Philippine Medical Technologists Licensure Examination (MTLE) and international certifications (such as ASCPi), mastery of regulatory donor standards, mathematical collection formulas, deferral classifications, infectious screening mandates under Republic Act No. 7719, and anticoagulant-preservative biochemistry is essential.

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1. Allogeneic Blood Donor Qualification and Physical Examination

All prospective blood donors must undergo a structured two-part assessment consisting of a confidential donor health history interview (using standardized donor history questionnaires) and a focused physical examination performed on the day of donation prior to phlebotomy.

                         ┌──────────────────────────────────────────────┐
                         │       Prospective Blood Donor Arrives        │
                         └──────────────────────┬───────────────────────┘
                                                │
                                                ▼
                         ┌──────────────────────────────────────────────┐
                         │   Confidential Health History Questionnaire  │
                         │     • High-risk behaviors, travel, meds      │
                         │     • Prior illnesses, surgeries, vaccines   │
                         └──────────────────────┬───────────────────────┘
                                                │ Passed
                                                ▼
                         ┌──────────────────────────────────────────────┐
                         │          Focused Physical Examination        │
                         │   • Age: ≥18 (16-17 with written consent)    │
                         │   • Weight: ≥110 lbs (50 kg)                 │
                         │   • Hgb: ♀ ≥12.5 g/dL; ♂ ≥13.0 g/dL          │
                         │   • BP: 90-180 / 50-100 mm Hg                │
                         │   • Pulse: 50-100 bpm; Temp: ≤37.5°C         │
                         │   • Bilateral antecubital inspection         │
                         └──────────────────────┬───────────────────────┘
                                                │ Qualified
                                                ▼
                         ┌──────────────────────────────────────────────┐
                         │            Phlebotomy & Testing              │
                         │   • Standard 450-500 mL collection ± 10%     │
                         │   • Mandatory RA 7719 5 Core TTI Testing     │
                         └──────────────────────────────────────────────┘

Physical Examination Criteria and Standards

• Age Requirements:
  • Minimum Age: $\ge 18\text{ years}$ for autonomous legal consent. Donors aged 16 to 17 years may donate provided they present written, documented parental or legal guardian consent and satisfy all physical examination metrics.
  • Upper Age Limit: There is no arbitrary upper age limit according to modern AABB and Philippine Department of Health (DOH) standards, provided the donor meets all medical history and vital sign requirements and has no clinical contraindications upon evaluation by the blood service physician.
• Body Weight and Blood Volume Limitations:
  • Minimum Weight: $110\text{ lbs}$ ($50\text{ kg}$) for a standard whole blood collection of $450\text{ mL} \pm 10\%$ (or $500\text{ mL} \pm 10\%$ in designated collection systems).
  • Physiological Basis: Total blood collection must not exceed $10.5\text{ mL per kilogram}$ of donor body weight (including sample tubes), which corresponds to approximately $13\%$ of total circulating blood volume. Drawing excessive volume relative to body mass precipitates acute hypovolemia, vasovagal syncope, and orthostatic hypotension.
  • Low-Weight Volume Reduction Calculation: Donors weighing less than $110\text{ lbs}$ ($50\text{ kg}$) who are eligible for specialized directed or autologous collections—or restricted allogeneic protocols—require proportional downward adjustments in both the volume of blood collected and the volume of anticoagulant-preservative in the collection bag. A standard primary collection pack contains $63\text{ mL}$ of anticoagulant-preservative (such as CPD or CPDA-1) designed for $450\text{ mL}$ of blood. If an under-volume unit ($<405\text{ mL}$) is collected into an unmodified $63\text{ mL}$ anticoagulant pack, the resulting excessive citrate-to-plasma ratio causes severe citrate toxicity (hypocalcemia, tetany, cardiac arrhythmias) in the recipient and distorts red cell morphology during storage.

$\text{Volume of Blood to Collect (mL)} = \left( \frac{\text{Donor Weight in lbs}}{110} \right) \times 450\text{ mL} \quad \text{or} \quad \left( \frac{\text{Donor Weight in kg}}{50} \right) \times 450\text{ mL}$

$\text{Anticoagulant Volume Needed (mL)} = \left( \frac{\text{Volume of Blood to Collect (mL)}}{450} \right) \times 63\text{ mL}$

$\text{Anticoagulant to Expel/Remove (mL)} = 63\text{ mL} - \text{Anticoagulant Volume Needed (mL)}$

Worked Clinical Calculation Example: A directed donor weighs $90\text{ lbs}$ ($40.9\text{ kg}$):

1. $\text{Blood to collect} = \left(\frac{90}{110}\right) \times 450\text{ mL} = 368.2\text{ mL} \approx 368\text{ mL}$.
2. $\text{Anticoagulant needed} = \left(\frac{368.2}{450}\right) \times 63\text{ mL} = 51.5\text{ mL}$.
3. $\text{Anticoagulant to remove} = 63\text{ mL} - 51.5\text{ mL} = 11.5\text{ mL}$. The phlebotomist must aseptically express and discard $11.5\text{ mL}$ of anticoagulant from the primary bag before initiating collection.

• Hemoglobin and Hematocrit Thresholds:

  • Allogeneic Female Donors: Hemoglobin $\ge 12.5\text{ g/dL}$ ($125\text{ g/L}$) or Hematocrit $\ge 38\%$.
  • Allogeneic Male Donors: Hemoglobin $\ge 13.0\text{ g/dL}$ ($130\text{ g/L}$) or Hematocrit $\ge 39\%$ (reflecting higher baseline male reference intervals and preventing latent donor iron depletion).
  • Autologous Donors: Hemoglobin $\ge 11.0\text{ g/dL}$ ($110\text{ g/L}$) or Hematocrit $\ge 33\%$.
  • Screening Methodologies: Quantitative automated point-of-care spectrophotometry (e.g., HemoCue) or capillary copper sulfate ($\text{CuSO}_4$) specific gravity flotation. For a hemoglobin threshold of $12.5\text{ g/dL}$, the copper sulfate solution has a specific gravity of $1.053$; for $13.0\text{ g/dL}$, the specific gravity is $1.055$. A drop of capillary blood that sinks within $15\text{ seconds}$ indicates acceptable density.

• Vital Signs Tolerances:

  • Blood Pressure: Systolic pressure must be between $90\text{ and }180\text{ mm Hg}$; diastolic pressure must be between $50\text{ and }100\text{ mm Hg}$. Moderate readings outside these boundaries require deferral until normalized or medical director authorization.
  • Pulse: $50\text{ to }100\text{ beats per minute (bpm)}$, regular. Highly trained conditioning athletes exhibiting physiological resting bradycardia ($<50\text{ bpm}$) are acceptable provided the rhythm is regular and clinical evaluation reveals no cardiopulmonary distress.
  • Body Temperature: Oral temperature must not exceed $37.5^\circ\text{C}$ ($99.5^\circ\text{F}$). Elevations indicate active pyrexia or subclinical infection.
  • Skin Inspection: Bilateral antecubital fossae must be rigorously examined. Venipuncture sites must be free from localized dermatological lesions, boils, psoriasis plaques, rashes, and crucially, needle tracks or sclerotic skin punctures indicative of illicit intravenous drug abuse.

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2. Donor Deferral Classifications and Regulatory Intervals

Donor deferrals are categorized according to their epidemiological duration into permanent (or indefinite) and temporary deferrals:

Permanent and Indefinite Deferrals

Individuals deferred permanently or indefinitely are excluded from allogeneic blood donation for life to prevent the transmission of incurable, fatal, or non-clearing blood-borne pathogens:

1. Viral Hepatitis: History of viral hepatitis, confirmed jaundice of viral etiology, or suspected hepatic infection at or after age 11 (infections occurring prior to age 11 are presumed to be benign, self-limiting Hepatitis A Virus infections and do not trigger permanent deferral).
2. Confirmatory Positive Serology or Molecular Testing:
   • Repeatedly reactive confirmed testing for Hepatitis B Surface Antigen (HBsAg) or persistent anti-HBc positivity.
   • Repeatedly reactive confirmed antibodies to Hepatitis C Virus (anti-HCV) or HCV RNA.
   • Confirmed evidence of infection with Human Immunodeficiency Virus (HIV-1/2) (anti-HIV, p24 antigen, or HIV-1 RNA).
   • Confirmed antibodies to Human T-Cell Lymphotropic Virus (anti-HTLV-I/II).
3. Parasitic Infections with Lifelong Parasitemia:
   • Confirmed infection with Chagas disease (Trypanosoma cruzi).
   • Confirmed history of Babesiosis (Babesia microti or Babesia divergens).
4. Prion Disease Transmission Risk (Transmissible Spongiform Encephalopathies):
   • Diagnosis of Creutzfeldt-Jakob Disease (CJD) or variant CJD (vCJD), or having a first-degree biological relative with familial CJD.
   • Recipients of cadaveric human pituitary-derived growth hormone (hGH).
   • Recipients of cadaveric human dura mater grafts.
   • Cumulative geographic residence in the United Kingdom or Europe during peak bovine spongiform encephalopathy (BSE) outbreak years (subject to regional regulatory threshold updates).
5. High-Risk Behavioral Histories:
   • Any history of non-prescription intravenous (parenteral) drug abuse.
   • History of commercial sex work (exchanging sex for money or drugs).

Temporary Deferrals

Temporary deferrals suspend donor eligibility for a discrete interval until the infectious window period, medication clearance, or physiological recovery phase has elapsed:

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3. Republic Act No. 7719 and Mandatory Infectious Disease Testing in the Philippines

In the Philippines, blood banking operations, voluntary donor recruitment, and hemovigilance are legally anchored by Republic Act No. 7719, known as the National Blood Services Act of 1994. RA 7719 phased out commercial blood banks, promoting exclusively voluntary, non-remunerated blood donation to guarantee a safe, accessible, and adequate national blood supply administered under the National Voluntary Blood Services Program (NVBSP) of the Department of Health (DOH).

The Five Core Transfusion-Transmissible Infections (TTIs)

Under RA 7719 and Administrative Orders issued by the Philippine DOH, every single unit of blood collected must be tested and confirmed non-reactive for the Five Core TTIs before release for clinical issue. No blood unit may bypass this testing:

1. Human Immunodeficiency Virus Types 1 and 2 (HIV-1/2):
   • Primary Serological Assays: 4th-generation Chemiluminescent Immunoassays (CLIA) or Enzyme Immunoassays (EIA) detecting both anti-HIV-1/2 antibodies and HIV-1 p24 antigen.
   • Significance: p24 antigen detection narrows the infectious seroconversion window from $\approx 22\text{ days}$ down to approximately $12\text{ to }16\text{ days}$ post-exposure.
2. Hepatitis B Virus (HBV):
   • Primary Serological Assays: Hepatitis B Surface Antigen (HBsAg) is the mandated Philippine screening marker; some blood services and most US blood centers add total antibodies to Hepatitis B core antigen (anti-HBc total).
   • Significance: Testing for anti-HBc captures "occult HBV infection"—cases where circulating HBsAg has cleared below analytical detection limits or is sequestered in immune complexes during the core window phase, yet infectious viral particles persist.
3. Hepatitis C Virus (HCV):
   • Primary Serological Assays: 3rd-generation CLIA/EIA detecting antibodies to HCV (anti-HCV) directed against core, NS3, NS4, and NS5 viral proteins.
4. Syphilis (Treponema pallidum):
   • Testing Algorithm: Non-treponemal screening assays (Rapid Plasma Reagin [RPR] or Venereal Disease Research Laboratory [VDRL]) detecting anti-cardiolipin antibodies, accompanied or confirmed by specific treponemal assays (Treponema pallidum Hemagglutination Assay [TPHA], TP-PA, or recombinant treponemal EIA).
   • Biological Note: Treponema pallidum is a fragile spirochete that cannot survive refrigeration at $1\text{ to }6^\circ\text{C}$ for greater than $72\text{ hours}$ ($3\text{ days}$). However, syphilis testing remains a mandatory surrogate marker for high-risk sexual behavior and protects recipients of room-temperature stored components (e.g., platelet concentrates).
5. Malaria (Plasmodium species):
   • Testing Modality: High-quality peripheral blood smear examination (thick and thin Giemsa/Wright-stained films) or approved Malaria Rapid Diagnostic Tests (RDTs) detecting Plasmodium lactate dehydrogenase (pLDH) or histidine-rich protein II (HRP-2).
   • Epidemiological Context: Given endemic foci across various provinces in the Philippines (e.g., Palawan, parts of Mindanao), universal screening for malaria parasites is an indispensable component of national transfusion safety.

Nucleic Acid Testing (NAT) and Window Periods

Some Philippine blood services (for example, Philippine Red Cross centers) and most high-income blood systems add Nucleic Acid Amplification Testing (NAT) (multiplex real-time transcription-mediated amplification [TMA] or PCR) for HIV-1 RNA, HCV RNA, and HBV DNA. NAT directly amplifies viral genomic material, closing the residual pre-seroconversion diagnostic window period to unprecedented safety margins:

• HIV-1 Window: Reduced from roughly $16\text{ to }18\text{ days}$ (4th-gen serology) to about $5\text{ to }9\text{ days}$ with NAT (individual-donation NAT at the short end, minipool NAT at the long end).
• HCV Window: Reduced from $60\text{ days}$ (serology) to $3\text{ to }5\text{ days}$ with NAT.
• HBV Window: Reduced from $35\text{ days}$ (HBsAg) to $15\text{ to }20\text{ days}$ with NAT.

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4. Anticoagulant-Preservative Formulations and Additive Solutions

When whole blood is collected, red cells must be preserved in specialized biochemical solutions that prevent clotting, provide glycolytic energy, buffer metabolic acid, and sustain erythrocyte membrane integrity.

                    ┌────────────────────────────────────────────────────────┐
                    │          Anticoagulant-Preservative Reagents           │
                    └───────────────────────────┬────────────────────────────┘
                                                │
             ┌──────────────────────────────────┴──────────────────────────────────┐
             ▼                                                                     ▼
  ┌───────────────────────┐                                             ┌───────────────────────┐
  │ Primary Anticoagulants│                                             │   Additive Solutions  │
  │  (In Collection Bag)  │                                             │   (Added to PRBCs)    │
  └──────────┬────────────┘                                             └───────────┬───────────┘
             │                                                                      │
   • ACD-A  (21 days)                                                     • AS-1 (Adsol)   - 42 days
   • CPD    (21 days)                                                     • AS-3 (Nutricel)- 42 days
   • CP2D   (21 days)                                                     • AS-5 (Optisol) - 42 days
   • CPDA-1 (35 days)                                                     Mechanism:
     Mechanism of Adenine:                                                • Saline, Dextrose, Adenine
     ATP salvage synthesis                                                • Mannitol (AS-1, 5) stabilizes
     maintains membrane pump                                                membrane, stops lysis

Primary Anticoagulant-Preservative Solutions (Storage at $1\text{ to }6^\circ\text{C}$)

1. Acid-Citrate-Dextrose (ACD-A): 21-day shelf life. Formulated with trisodium citrate (chelates calcium to block coagulation), citric acid (maintains acidic pH), and dextrose (serves as substrate for anaerobic glycolysis).
2. Citrate-Phosphate-Dextrose (CPD): 21-day shelf life. Incorporates sodium phosphate, which buffers pH to $\approx 7.2$ during early storage, preserving higher levels of 2,3-diphosphoglycerate (2,3-DPG) compared to ACD.
3. Citrate-Phosphate-Double Dextrose (CP2D): 21-day shelf life. Contains 100% additional dextrose relative to CPD, fueling extended red cell glycolysis.
4. Citrate-Phosphate-Dextrose-Adenine (CPDA-1): 35-day shelf life. Formulated with $0.275\text{ mg/mL}$ adenine alongside citrate, phosphate, and dextrose.
   • Biochemical Role of Adenine: Adenine serves as an essential purine substrate for the red cell salvage pathway. Erythrocytes synthesize adenosine triphosphate (ATP) from adenine, keeping intracellular ATP levels high. Elevated ATP maintains the $Na^+/K^+$-ATPase pump, preserves erythrocyte membrane deformability, and suppresses membrane phospholipid loss, extending shelf life from 21 to 35 days.

Additive Solutions (AS-1, AS-3, AS-5)

Additive solutions are sterile nutrient media stored in a satellite pack ($100\text{ to }110\text{ mL}$) and introduced to packed red blood cells within 72 hours of collection after plasma has been expressed. Additive solutions extend red blood cell shelf life to 42 days at $1\text{ to }6^\circ\text{C}$:

• AS-1 (Adsol): Formulated with sodium chloride, dextrose, adenine, and mannitol (mannitol acts as an osmotic diuretic and membrane stabilizer that protects against erythrocyte lysis).
• AS-3 (Nutricel): Formulated with sodium chloride, dextrose, adenine, citrate, and phosphate (no mannitol; preferable for neonatal exchange transfusions to prevent osmotic diuresis).
• AS-5 (Optisol): Formulated with sodium chloride, dextrose, adenine, and mannitol.
• Regulatory Standard: Units preserved with additive solutions maintain a hematocrit of $55\%\text{ to }65\%$, providing superior flow rates during rapid infusion compared to CPDA-1 units ($Hct \le 80\%$).

The Erythrocyte Storage Lesion

During hypothermic liquid storage at $1\text{ to }6^\circ\text{C}$, red blood cells undergo progressive, reversible and irreversible biochemical, structural, and physiological deteriorations known collectively as the storage lesion:

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5. Donor Eligibility, Vital Signs, and Deferral Matrix