Sending pathology samples by courier: UN3373 explained in plain English
What UN3373 Category B means, how samples must be packed, what a courier is and isn't allowed to carry, and how to book a same-day sample run in the West Midlands.
Clinics, vets, dental practices and research labs across the West Midlands need blood, swabs and tissue samples moved to a laboratory the same day, every day. The rules are simpler than they look. Here's what matters.
Category A, Category B and exempt
- Category A (UN2814 / UN2900): substances capable of causing life-threatening disease, such as cultures of Ebola or certain high-risk pathogens. Specialist carriers only. We do not carry these.
- Category B (UN3373): diagnostic and clinical specimens that don't meet Category A: routine blood, urine, swabs, biopsies, veterinary samples. This is the vast majority of everyday sample work, and we carry it as standard.
- Exempt specimens: samples where there is minimal likelihood of pathogens being present, such as screening tests. Packed in a leak-proof container with absorbent material and labelled 'Exempt human specimen' or 'Exempt animal specimen'.
Who is responsible for what
The sender classifies and packs. The courier carries and documents. A courier cannot open, repack or inspect the inner packaging, so if a sample arrives at the lab wrongly packed, the sender is responsible. Good couriers will refuse a package that is visibly wrong, which protects you as much as them.
How Category B samples must be packed (P650)
- 1.Primary receptacle: the leak-proof tube or pot holding the sample.
- 2.Secondary packaging: a leak-proof bag or container with enough absorbent material to soak up the entire contents if the primary leaks.
- 3.Rigid outer packaging: a box at least 100 mm on its smallest side, marked with the UN3373 diamond and the words 'Biological Substance, Category B', plus the sender's and receiver's names and phone numbers.
- 4.Itemised list of contents between the secondary and outer packaging.
Most pathology suppliers sell pre-approved UN3373 boxes for under £2 each. Using them removes any argument about compliance.
What the driver does
- Keeps the package upright, secured, and out of direct sunlight.
- Carries a spill kit and knows the basic response: isolate, don't touch, call the sender and the lab.
- Hands over to a named person at the laboratory reception, never a post room or a locker.
- Records a photo, time and GPS at both ends. You get the proof of delivery PDF immediately.
What about temperature?
Most Category B samples are fine at ambient temperature for the few hours a same-day run takes. If your lab specifies chilled or frozen transport, that's a separate requirement from UN3373: it needs a validated cool box with a temperature logger, or a refrigerated vehicle. Tell us when you book and we'll arrange it or tell you honestly if we can't.
Booking a sample run
Choose Car as the vehicle (unless you're sending a lot of boxes), pick 'Pathology samples (UN3373 Category B)' as the goods type so the driver gets the handling instructions, and enter the lab reception as the delivery contact. Regular daily runs for practices and clinics are cheaper on a business account.
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