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Hematology

Prevention of Infection

The prevention of infection from bloodborne pathogens is the cornerstone of laboratory safety programs, particularly in Hematology where the manipulation of whole blood, the creation of glass slides, and the performance of venipunctures and capillary punctures are daily activities. The primary regulatory framework governing this area in the United States is the Occupational Safety and Health Administration (OSHA) Bloodborne Pathogens Standard (29 CFR 1910.1030). This federal regulation mandates that employers protect employees from occupational exposure to infectious agents, specifically Hepatitis B Virus (HBV), Hepatitis C Virus (HCV), and Human Immunodeficiency Virus (HIV)

Standard Precautions

The fundamental philosophy driving infection control in the clinical laboratory is Standard Precautions. This concept, an expansion of the earlier “Universal Precautions,” dictates that all human blood, body fluids, secretions, excretions (except sweat), non-intact skin, and mucous membranes must be treated as if they are known to be infectious for HIV, HBV, and other bloodborne pathogens. There are no exceptions; a specimen from a healthy individual is handled with the exact same rigor as a specimen from a patient in an infectious disease ward

  • Applicability: Standard precautions apply to all patients and all specimens in the Hematology laboratory, including venous blood, capillary blood, bone marrow aspirates, and body fluids (CSF, synovial, pleural)
  • Operational Mindset: The laboratory scientist must assume that every tube of blood creates a potential vector for disease transmission through percutaneous injury (needlestick), mucous membrane contact (splash to eyes/mouth), or non-intact skin exposure (dermatitis/cuts)

The Exposure Control Plan (ECP)

OSHA requires every laboratory to have a written Exposure Control Plan. This document is the “playbook” for safety and must be accessible to all employees. It details the determination of employee exposure, the schedule and method of implementation for compliance, and the procedure for evaluating exposure incidents. It must be reviewed and updated at least annually to reflect changes in technology that eliminate or reduce exposure to bloodborne pathogens (e.g., the adoption of new safety-engineered devices)

Engineering Controls

Engineering controls are the primary means of eliminating or minimizing employee exposure. These are physical devices or equipment that isolate or remove the bloodborne pathogens hazard from the workplace. These controls function independently of the worker’s behavior; they are built into the infrastructure or tools of the lab

  • Safety Needles and Lancets: Phlebotomy equipment must incorporate safety-engineered features, such as sheaths that slide over needles or needles that retract into the holder immediately after use. In Hematology POCT, retractable single-use lancets are mandatory to prevent re-use or accidental sticks
  • Sharps Containers: Rigid, puncture-resistant, leak-proof containers labeled with the biohazard symbol must be easily accessible in the immediate work area. These must not be overfilled (replaced when 3/4 full)
  • Plastic Capillaries: The replacement of glass hematocrit tubes with plastic or Mylar-wrapped glass tubes reduces the risk of laceration and subsequent inoculation with blood if a tube breaks during centrifugation
  • Biosafety Cabinets: While routine CBCs are processed on the bench, processing body fluids (which may aerosolize) or bone marrow slides should be performed behind splash shields or within a biological safety cabinet
  • Self-Sealing Tubes: Vacuum tubes used for collection should have closures that minimize splatter when removed. Modern hematology analyzers utilize cap-piercing technology, allowing the instrument to sample blood without the operator ever removing the stopper, significantly reducing aerosol exposure

Work Practice Controls

Work practice controls alter the manner in which a task is performed to reduce the likelihood of exposure. Unlike engineering controls, these rely on the behavior and compliance of the laboratory scientist

  • Hand Hygiene: This is the single most effective way to prevent the spread of infection. Hands must be washed with soap and water immediately after removing gloves and after any contact with blood. Alcohol-based hand rubs are acceptable only if hands are not visibly soiled
  • Prohibited Activities: Eating, drinking, smoking, applying cosmetics or lip balm, and handling contact lenses are strictly prohibited in technical work areas. Food and drink must never be stored in refrigerators, freezers, or cabinets where blood or other potentially infectious materials are stored
  • Minimizing Aerosols
    • Centrifuges must be capped or have sealed buckets. If a breakage is suspected, the centrifuge must be turned off and allowed to rest for 30 minutes to let aerosols settle before opening
    • When manually uncapping a tube (e.g., for a manual reticulocyte count), the top should be covered with gauze and twisted gently away from the face to catch any spray
  • Sharps Handling: Needles must never be sheared, bent, broken, or recapped by hand (unless using a mechanical device or a one-handed scoop technique). The activation of safety devices should occur immediately after the procedure

Personal Protective Equipment (PPE)

When engineering and work practice controls cannot fully eliminate hazards, PPE provides a barrier between the worker and the infectious material. Employers must provide PPE at no cost to the employee

  • Gloves: Must be worn for all phlebotomy procedures and when handling blood specimens. Latex or Nitrile are standard (vinyl is generally insufficient for blood risks). They must be replaced immediately if torn or punctured and must never be washed or reused
  • Lab Coats: Fluid-resistant laboratory coats or gowns with knit cuffs are required. They must be buttoned completely. PPE must be removed before leaving the work area (e.g., going to the breakroom or restroom) to prevent “take-home” contamination
  • Face Protection: If there is a risk of splashing or aerosolization (e.g., opening centrifuge buckets, uncapping tubes, making manual slides), the laboratory scientist must wear a face shield or a combination of a mask and eye protection (goggles/glasses with side shields)

Hepatitis B Vaccination Program

OSHA mandates that the Hepatitis B vaccination series must be made available to all employees who have occupational exposure

  • Availability: The vaccine must be offered at no cost, at a reasonable time and place, and within 10 working days of initial assignment
  • Declination: Employees who choose not to accept the vaccine must sign a mandatory declination statement. The employee retains the right to accept the vaccination series at a later date if they change their mind
  • Antibody Testing: Post-vaccination testing for anti-HBs is recommended to verify immunity (seroconversion). If the employee does not develop antibodies, a second series or evaluation for non-responder status is indicated

Post-Exposure Evaluation & Follow-up

Despite all precautions, exposure incidents (needlesticks, splashes to the eye) can occur. A strict protocol must be followed immediately

  • Immediate Care: Wash needlesticks and cuts with soap and water. Flush splashes to the nose, mouth, or skin with water. Irrigate eyes with clean water, saline, or sterile irrigant (eyewash station) for 15 minutes
  • Reporting: The incident must be reported to the supervisor immediately. An incident report is generated to document the route of exposure and the circumstances
  • Source Evaluation: Unless the source is known to be infected, the source individual’s blood must be tested (with consent, per local law) for HBV, HCV, and HIV infectivity as soon as feasible
  • Employee Evaluation: The exposed employee’s blood is collected for baseline serological status. Post-Exposure Prophylaxis (PEP) may be administered based on the risk assessment (e.g., antiretroviral therapy for high-risk HIV exposure). Follow-up testing is conducted at intervals (e.g., 6 weeks, 12 weeks, 6 months) to monitor for seroconversion

Waste Management

Proper disposal of infectious waste is critical to preventing downstream exposure for custodial staff and the public

  • Biohazard Bags: “Red bag” waste is reserved for items that are liquid/semi-liquid blood or other potentially infectious materials (OPIM), or items that would release blood if compressed (caked with dried blood). Routine items like slightly soiled gloves or paper towels usually go in regular trash, depending on state laws
  • Sharps Disposal: All needles, lancets, slides, and broken glass contaminated with blood must go into sharps containers. Glass slides are a specific hazard in Hematology; they should never be discarded in soft biohazard bags where they can puncture the plastic and injure handlers