Specimen Bags and Viral Transport Media: What Canadian Labs Pair Together
A specimen does not travel as a single object. A swab or a tube of fluid, the medium that keeps it viable, and the bag that contains it are a set, and each part is chosen against the others. For a Canadian lab, pairing the bag with the transport medium is a routine decision that decides whether a sample is still usable when it reaches the bench.
What goes inside a specimen bag with viral transport media?
Three things travel together. The primary container, whether a swab in its medium, a plain tube or a graduated cup, holds the sample. Around it sit the absorbent layer and the secondary bag, which contain a leak if the primary container fails. The requisition rides in a separate pocket so it never touches the sample.
Which bag size fits a viral transport tube?
A transport tube is tall and narrow, so it needs a bag that keeps it upright rather than one that lets it lie flat and weep at the cap. A 7 x 11 inch 95 kPa specimen bag holds a tube with its requisition, while a 6 x 9 inch bag covers a single swab or a small tube on a short route.
| Sample or container | Bag size | Why |
|---|---|---|
| Single swab in transport medium | 6 x 9 inch | Compact, one container per bag |
| One transport tube plus requisition | 7 x 11 inch | Keeps the tube upright |
| Small panel of tubes | 8 x 10 inch | Fits a small rack and the form |
| 90 mL graduated cup | 8 x 10 or 12 x 15 inch | A larger primary container needs headroom |
What does UN3373 require for the pairing?
Category B specimens travel as UN3373, and the packaging has to hold a 95 kPa pressure difference, the same figure the bag is rated to. Triple packaging applies: a leak-proof primary container, an absorbent layer to soak up a spill, and a rigid outer box. The bag is the secondary packaging inside that box, not a replacement for it. Pairing a 90 mL graduated specimen cup with an undersized bag is the kind of mismatch that fails at the seal.
How should the bag and the swab be matched?
Match the bag to the primary container, not to the test name. A slim swab tube, a plain tube of fluid at room temperature, and a refrigerated sample each ask for a slightly different bag. The receiving lab's collection instructions settle the choice; the bag then has to physically hold that container without tipping.
What do Canadian labs check before pairing?
That the tube stands upright in the bag, that the absorbent layer is sized to the primary volume, and that the requisition has its own pocket. A pairing that survives a drop at the bench is the one that reaches the lab intact, so it is worth testing one before committing a case to it.
Pairing it in one order
When the bag, the 120 mL sterile screw-cap container and the swab all come from one supplier, the containers and the bags are sized against each other rather than guessed. That is the point of ordering the set together.
Running a diagnostic or research laboratory? See our laboratory and diagnostic supplies for the receiving bench.
Ordering for a clinic, lab or care home? Wholesale and multi-site ordering covers case pricing and account setup, and the B2B wholesale collection lists the lines stocked for institutional buyers.
A printable specimen-receipt and pairing checklist sits in the free log and template centre, alongside a packing planner.
References
- World Health Organization — Guidance on the transport of infectious substances (checked 3 October 2026)
- International Air Transport Association — Dangerous Goods Regulations (checked 3 October 2026)
- Public Health Ontario — Reprocessing and specimen handling (checked 3 October 2026)
Related Reading
- Specimen bag station setup checklist for Canadian diagnostic laboratories
- 95kPa Specimen Bags: Choosing UN3373 Category B Packaging
- Microbiology Culture Swabs: Types and Transport for Canadian Labs
Frequently Asked Questions
What goes inside a specimen bag with viral transport media?
The primary container with the swab or fluid, an absorbent layer sized to the volume, and the requisition in its own pocket, all inside the 95 kPa bag.
Which bag size fits a viral transport tube?
A 7 x 11 inch bag keeps a tall transport tube upright; a 6 x 9 inch bag suits a single swab or small tube on a short route.
Is the 95 kPa bag itself the UN3373 packaging?
No. The bag is the secondary packaging; UN3373 Category B still needs a leak-proof primary container and a rigid outer box.
How do I match the bag to the sample?
Match it to the primary container rather than the test name, so the tube stands without tipping and the absorbent layer fits the volume.
Last updated: October 2026. CliniEco Medical is a licensed medical device establishment (MDEL #35334).
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