What items should be on a specimen container?

Specimen containers are essential tools in healthcare, designed to safely and effectively collect and preserve biological samples for various diagnostic tests. The specific contents and design of a specimen container are tailored to the type of sample being collected and the analyses to be performed, ensuring the integrity of the specimen and the accuracy of test results.

Blood Specimen Containers

Blood collection requires specialized tubes, each distinguished by color-coded tops that indicate the presence of specific additives.

Separation Tube (Yellow Top): These tubes are primarily used for clinical biochemistry and immunology testing. They contain a blood coagulation activator to promote clot formation and a separation gel that, after centrifugation, forms a barrier between serum and blood cells, allowing for easy serum collection.

Heparin/Heparin Sodium Anticoagulant Tube (Green or Brown Top): Ideal for clinical biochemistry, immunology, blood rheology, and cytogenetic testing, these tubes contain heparin or heparin sodium. These anticoagulants work by inactivating coagulation factors IIa and Xa, preventing blood from clotting.

EDTA Anticoagulant Tube (Purple Top): Employed for hematology testing, glycated hemoglobin assays, and cross-matching, these tubes contain dipotassium ethylenediaminetetraacetate (EDTA-K₂) or tripotassium ethylenediaminetetraacetate (EDTA-K₃). EDTA chelates calcium ions, which are crucial for the coagulation cascade, thereby inhibiting blood clotting.

Coagulation Tube (Light Blue Top): Used for coagulation function and platelet function testing, these tubes contain sodium citrate in a 1:9 ratio with blood. Sodium citrate acts as an anticoagulant by chelating calcium ions.

Erythrocyte Sedimentation Rate (ESR) Tube (Black Top): Specifically designed for ESR testing, these tubes also contain sodium citrate, but in a 1:4 ratio with blood. This concentration allows red blood cells to remain suspended for a period, facilitating the measurement of their sedimentation rate.

Blood Culture Bottle: These bottles are used for microbial culture from blood samples and come in aerobic and anaerobic variants. Aerobic collection bottles typically contain a rich culture medium like Bactec, while anaerobic collection bottles contain Bactec medium that is pre-reduced with carbon dioxide and nitrogen to create an oxygen-free environment. They are designed to accommodate 8-10 ml of whole blood.

Body Fluid Specimen Containers

Containers for other body fluids are designed to maintain sample integrity for diverse analyses.

Urine Cup: A ubiquitous container for urine collection, typically disposable and equipped with a screw cap or no cover. These cups are clean, leak-proof, free of particles, and made from materials that do not interfere with the detected components, suitable for routine urinalysis, biochemistry, and immunology tests.

Containers for Sputum, Pleural Effusion, Ascites, Cerebrospinal Fluid (CSF), etc.: These are generally disposable, sterile containers with screw caps, ensuring a clean, leak-proof environment free from interfering substances for the collection of various body fluids for specialized testing.

Stool Collection Containers: These usually feature hand-lift lids or screw caps and often include a sampling spoon. They are clean, leak-proof, and free of interfering substances, used for routine stool tests, fecal occult blood, and fecal calprotectin assays. Disposable urine cups can also serve this purpose.

Secretion Specimen Containers

Collection of secretions often involves swabs or specialized brushes with preservation media.

Secretion Swabs: These include various disposable sterile swabs, such as nasal/pharyngeal, female, and male swabs, designed for collecting secretions from specific anatomical sites for pathogen detection.

Cervical Cell Brush and Cell Preservation Fluid: Crucial for cervical secretion liquid-based cytology (TCT) and human papillomavirus (HPV) testing. Cervical cells are collected with a brush and immediately transferred into a specialized cell preservation fluid for transport and storage, maintaining cellular integrity.

Other Specimen Containers

Beyond common bodily fluids, specialized containers exist for molecular diagnostics.

Viral Nucleic Acid Sampling Tube: These tubes contain nucleic acid preservation fluid and buffer to stabilize viral genetic material. They are used for collecting throat swabs and other specimens for viral nucleic acid testing, including pertussis, influenza A and B, COVID-19, and other respiratory viral panels.

Free DNA Preservation Tube: Designed for non-invasive DNA testing, these tubes contain specific free DNA preservation additives that stabilize circulating cell-free DNA in whole blood samples.

The contents of a specimen container are meticulously chosen to ensure optimal sample integrity, prevent degradation, and facilitate accurate diagnostic testing, making them an indispensable component of modern laboratory medicine.