A Comprehensive Technical Overview

A grossing station, also known as a pathology dissection table or biological safety cabinet for gross examination, is an engineered containment system designed to provide a controlled environment for the macroscopic examination, dissection, and sampling of surgical specimens. These specialized workstations ensure both personnel protection and specimen integrity through advanced ventilation and filtration systems.

Key terminology includes:

Grossing stations operate on the principle of laminar airflow and negative pressure containment. Ambient room air is drawn through the front grille at a precisely controlled velocity, typically between 0.4-0.6 m/s, creating an air barrier that prevents the escape of contaminants. This air mixes with contaminants generated during dissection and is immediately captured.

The contaminated air is then pulled downward through the perforated work surface. A portion of this air is exhausted through dedicated ducting after passing through HEPA filtration, while the remainder is recirculated within the workstation after passing through the main HEPA filter, creating a sterile work environment. In fully exhausted systems, all contaminated air is filtered and expelled to the outside atmosphere.

Shields pathologists and technicians from biohazardous aerosols, formaldehyde, and other volatile chemicals used in tissue fixation.

Maintains a clean environment to prevent cross-contamination between specimens during examination and dissection.

Provides an integrated area for dissection with features like adjustable height, built-in lighting, and easy access to tools.

Contains and properly filters hazardous vapors and particulates before safe exhaust or recirculation.

Grossing stations are constructed from materials selected for chemical resistance, durability, and cleanability. The work surface is typically made of 316-grade stainless steel, which is non-porous, corrosion-resistant, and easy to disinfect. Surfaces are often electropolished for smoothness.

The cabinet body is constructed from powder-coated carbon steel or stainless steel, providing structural integrity and resistance to chemical spills. The splash guard is made of clear, shatter-resistant polycarbonate or acrylic to provide visibility while protecting the user. Filters are housed in sealed compartments to prevent leakage.

Integral components often include a cold-light source for illumination, integrated sink with hot/cold water, air/water vacuum aspirators, and electrical outlets.

Grossing stations are classified based on their airflow pattern and exhaust type, primarily following NSF/ANSI 49 standards. Standard models typically feature an internal work area of approximately 48" x 24" with external dimensions around 60"W x 36"D x 48"H. Airflow volumes range from 700-900 CFM for standard models to 1000-1300 CFM for larger units.

Inflow velocity is maintained at 0.50 ± 0.05 m/s for most models, while downflow velocity ranges from 0.25-0.35 m/s. All systems employ HEPA filtration with 99.99% efficiency. Motor power requirements range from 1.0-1.5 HP for standard models to 1.5-2.5 HP for larger or fully exhausted systems. Noise levels are maintained below 65-68 dBA depending on the model.

Electrical requirements vary from 115V, 15A for standard models to 208V/240V, 20A for larger systems with full exhaust capabilities.

While primarily found in healthcare pathology laboratories, grossing stations are also essential in reference laboratories handling diverse specimen types, academic medical centers for both clinical work and research involving human tissues, and medical examiner/forensic laboratories for autopsy specimen examination and toxicology sampling.

Additional applications include veterinary diagnostic laboratories for processing animal tissue specimens and pharmaceutical research facilities conducting histopathological analysis during drug development and safety testing.

Proper installation is critical for performance and compliance with standards such as GMP, ISO 14644 (Cleanrooms), NSF/ANSI 49, and CDC/NIOSH guidelines. Installations should be located away from high-traffic areas, doors, and air vents to minimize air turbulence that can disrupt the protective air curtain.

Maintain minimum clearances (usually 6-12 inches) from walls and obstacles for proper airflow and maintenance access. Place on a stable, level floor to prevent vibration that could affect scale measurements or filter integrity. For ducted models, exhaust ducting must be properly sized and sealed with the exhaust fan located downstream of the cabinet to maintain negative pressure within the ductwork.

Electrical and plumbing requirements include dedicated circuits and proper grounding. Plumbing for integrated sinks must include traps for formalin and biological waste. All installations must be performance-certified by a qualified technician after installation and any relocation.

A rigorous maintenance schedule is essential to ensure continuous protection and operational efficiency. Daily maintenance includes wiping down all interior and exterior surfaces with a mild detergent followed by a disinfectant such as 70% ethanol or diluted bleach solution.

Weekly and monthly maintenance involves inspecting and cleaning or replacing pre-filters as needed, checking and cleaning the perforations in the work surface to ensure unobstructed downflow, testing and calibrating integrated scales, and checking UV lamps for intensity and replacement according to manufacturer specifications.

Bi-annual and annual maintenance must include certification by a qualified technician who tests face and downflow velocities, conducts HEPA filter integrity testing, and performs smoke pattern testing. HEPA filters typically require replacement every 5-7 years, or when pressure drop indicates clogging, or if integrity testing fails. This is a specialized task requiring recertification afterward.

Maintain a detailed logbook for all cleaning, maintenance, repairs, and certifications to ensure traceability and compliance with accreditation standards such as CAP and JC.