A specimen bag par level is an arithmetic problem before it is a purchasing problem: take the daily accession count, multiply by the number of bags one accession consumes, add a resend allowance, multiply by working days, and set the order point at one to two weeks of cover. The bag itself is secondary packaging for a Category B infectious substance, and the UN3373 specimen transport bag, 7 × 11 inch with document pouch, 95 kPa, 100 per pack is the format most Ontario laboratories standardise on because it carries the absorbent and the paperwork in one unit.
Quick facts
- 95 kPa is not a marketing figure: US hazardous materials rules for Category B infectious substances require packaging capable of withstanding, without leakage, an internal pressure producing a pressure differential of not less than 95 kPa (0.95 bar, 14 psi).
- The bag is the secondary packaging in the three-layer system: primary receptacle, absorbent and secondary packaging, then a rigid outer packaging.
- ISO 15189:2022 is the current standard for medical laboratory quality and competence; the 2012 edition was withdrawn on 6 December 2022, so an accreditation document that still cites it cites a superseded edition.
- A bag with a document pouch keeps the requisition outside the specimen compartment, which is what allows the laboratory to read the request without opening the bag.
- Bag consumption is driven by accessions plus exceptions, not by test count: a split specimen, a leaked bag, a mislabelled request and a repeat all consume a bag without producing a billable test.
- Laboratories that set a par level in cases rather than in weeks usually discover the mismatch at the worst time — during a send-out run with a courier already at the door.
What actually drives monthly bag consumption?
Four variables, and only one of them is visible on the accession report.
Accessions. The count the laboratory already tracks. One accession usually means one bag, but a panel that needs a separate container for each analyte can mean two or three.
Split specimens. A single request that requires serum, plasma and urine produces three primary receptacles, and a laboratory that is sending all three to a referral site may combine them in one bag or separate them by destination. The destination is the deciding factor, not the analyte.
Rejections and resends. A specimen that arrives without the request, with a mismatched label or in a bag that leaked has to be recollected, and the recollection consumes a second bag. Laboratories that never model this line are always short at month end.
Send-out packaging. A referral laboratory may repackage what it receives into its own secondary packaging, which means one inbound bag becomes one or more outbound bags. If the laboratory does any referral work, this line can dominate the total.
A fifth variable is quieter: bag damage in storage. A case stored against a wall in a humid room, or a box crushed under other stock, produces bags that fail at the seam. The fix is shelf discipline, not a bigger order.
How do you turn accession volume into a par level?
The method is a five-line calculation, and every line should be visible in the laboratory's own numbers rather than borrowed from another site. The table below is a worked example for a laboratory running 250 accessions a day over 21 working days.
| Line | How it is derived | Worked example |
|---|---|---|
| Daily bag demand | Daily accessions × bags per accession | 250 × 1.2 = 300 bags |
| Exception allowance | Resends and splits, as a percentage of daily demand | 300 × 5% = 15 bags |
| Monthly demand | (Daily demand + exception) × working days | 315 × 21 = 6,615 bags |
| Safety stock | One to two weeks of cover for delivery slippage | 315 × 10 = 3,150 bags |
| Order point | Remaining stock at which the next order is released | 3,150 bags on hand |
Read the last two lines together, because that is where most laboratories go wrong. Safety stock is not extra stock sitting in a cupboard; it is the quantity that covers the gap between "we need to order" and "the order arrives". A laboratory that orders monthly and holds nothing is one late delivery away from sending specimens in whatever bag is available, which is exactly the situation a 95 kPa requirement exists to prevent.
Two refinements are worth the ten minutes. First, count bags per accession for a week rather than assuming 1.0 — a laboratory that runs a lot of urines and swabs on the same request will find the real figure is higher. Second, review the exception allowance quarterly: a jump in resends is a labelling or packaging problem that shows up in the bag count before it shows up in the quality report.
What must the bag itself do?
Three things, and a buyer can test all three by asking for the documentation.
Withstand the pressure differential. US rules for Category B infectious substances require the packaging to withstand an internal pressure differential of not less than 95 kPa without leakage (49 CFR 173.199). Canada's transport rules derive from the same UN Model Regulations that the US rule implements, so a bag specified to 95 kPa with a test report is what a laboratory should be able to produce on request.
Contain the absorbent. The secondary packaging has to hold enough absorbent to take the entire liquid content of the primary receptacles in the event of a break. A bag with an integrated absorbent pad does that in one unit; a bag without one requires the laboratory to add absorbent separately, and that step is the one that gets skipped at 4 p.m. on a Friday.
Carry the paperwork without contaminating it. The document pouch is a compliance feature, not a convenience: it lets the requisition travel with the specimen while staying outside the specimen compartment, so a leaking primary receptacle does not destroy the request.
Beyond the three, the practical questions are closure (a pressure-sensitive adhesive strip that stays closed through handling), dimensions against the containers actually used, and whether the bag is printed with the UN3373 mark or requires a separate label. None of these are regulated in the same way as the 95 kPa figure, and all of them decide whether the bag works in the laboratory's hands.
How do Canadian and American requirements differ for specimen transport?
| Question | Canada | United States |
|---|---|---|
| What the transport rules implement | The UN Model Regulations, through federal dangerous goods legislation | 49 CFR Parts 171 to 180, with Category B infectious substances addressed in 173.199 |
| The pressure requirement on the packaging | The 95 kPa pressure differential, as carried through the UN Model Regulations | Explicit 95 kPa differential stated in 173.199 |
| Who accredits the laboratory | Provincial or national accreditation against ISO 15189:2022 | Accreditation bodies recognised under the Clinical Laboratory Improvement Amendments |
| What the laboratory's quality system has to cover | Specimen collection, transport, handling, examination and reporting under ISO 15189:2022 | The same activities under CLIA requirements plus ISO 15189:2022 where the laboratory is accredited to it |
| Record that a courier or inspector may ask for | Packaging specification, training records and incident records | The same three, in the format the regulator or accreditation body expects |
The comparison is easy to misread in one direction: the 95 kPa figure looks like an American number because it appears in a US rule, but it is a UN figure that both countries carry. The genuine difference is where the laboratory's obligations sit — in Canada the accreditation and provincial requirements do most of the work, while in the United States the CLIA framework sits alongside the transport rules.
Why does ISO 15189:2022 matter to a bag order?
Because it makes the bag part of an auditable process rather than a consumable. ISO 15189:2022 sets out requirements for quality and competence in medical laboratories, and it covers the pre-examination phase, which is where specimen collection, transport and receipt sit (ISO 15189:2022). The 2012 edition that many laboratory manuals still quote was withdrawn on 6 December 2022 (ISO 15189:2012); an SOP that cites the old edition is not wrong about the practice, but it is citing a document that no longer defines the requirement.
For a purchasing manager the practical consequence is that the bag specification, the storage conditions and the acceptance criteria on receipt all belong in the quality system. That means the order should carry the specification, the receipt check should be recorded, and the storage conditions should be the ones the manufacturer states — not the ones the stockroom happens to have.
How should the order itself be structured?
Three decisions: case size, order frequency and delivery terms.
Case size. A 100-per-pack bag is convenient for a small laboratory and inefficient for one running thousands a month, because the pack is opened and handled more often. Most independent laboratories settle on a case quantity that matches two to four weeks of demand, which also caps the space needed for storage.
Order frequency and the order point. A standing monthly order with a two-week safety stock is easier to administer than a reactive order, and it makes the par level auditable: the laboratory can show what it expected to use and what it used.
Delivery terms. Lead time is the variable that turns a par level into a stock-out. Ask for the supplier's stated lead time, then set the order point on the longer of that lead time and the internal approval time, and write both into the purchasing record. Where an account is being set up, the wholesale supply route is where case quantities, standing orders and delivery schedules are agreed; the sterilization monitoring collection is where the bag sits beside the indicators and packaging a laboratory also consumes. Reselling? become a distributor.
What belongs in the receiving record?
Four fields, and they are the same four an auditor asks for: lot number, quantity, date received, and the condition of the case. A bag that has been compressed, stored damp or exposed to sunlight may still pass a visual check and fail in use, so the receiving record should note the storage location as well as the condition.
Print a receiving sheet before the first delivery rather than reconstructing one afterwards; the printable compliance log set includes dated lines for consumable receipt and storage checks, and the log generator on the same page will lay out a sheet for the storage locations the laboratory actually uses.
Where the par level has to be defended to an accreditation assessor, the compliance consultation desk answers in writing with the standard or regulation the answer rests on, specific to the laboratory's equipment and province — no account and no sign-up needed.
Sources
All links checked 23 October 2026.
- 49 CFR 173.199, Category B infectious substances
- ISO 15189:2022, Medical laboratories — Requirements for quality and competence
- ISO 15189:2012, superseded edition — withdrawn 6 December 2022
- ISO 17664-1:2021, Processing of health care products — Information to be provided by the medical device manufacturer
- ISO 11607-1:2019, Packaging for terminally sterilized medical devices
- CLSI M29: Protection of laboratory workers from occupationally acquired infections
- CLSI GP48: Essential elements of a phlebotomy training program
- Public Health Ontario: provincial guidance on cleaning, disinfection and sterilization in all health care settings
- WHO: decontamination and reprocessing of medical devices for health-care facilities
- CliniEco Medical: specimen bags and transport consumables
Related reading
- How are specimen bags pressure-tested? What 95 kPa certification means for labs
- Specimen bag 95 kPa documentation: what Canadian labs require
- Specimen bag station setup checklist for Canadian diagnostic laboratories
Frequently Asked Questions
How many specimen bags should a laboratory hold as safety stock?
One to two weeks of average demand is a workable default, set from the supplier's stated lead time rather than from a round number. A laboratory that orders once a month needs the longer end; one that receives weekly deliveries can hold less. The number should be written into the purchasing record with the lead time it assumes.
Is 95 kPa a Canadian requirement or an American one?
It is a UN figure that both countries carry into their transport rules. The US states it explicitly for Category B infectious substances in 49 CFR 173.199, and Canada implements the same UN Model Regulations through federal dangerous goods legislation. A supplier that markets a bag as "Canadian 95 kPa" and cannot produce a test report is offering a number rather than evidence.
Does the bag need an absorbent pad?
The secondary packaging has to be able to absorb the entire liquid content of the primary receptacles if they break. A bag with an integrated absorbent pad does that in one unit; a bag without one requires the laboratory to add absorbent, and that is the step most likely to be skipped under time pressure.
Why do we use more bags than accessions?
Because splits, resends and send-outs all consume a bag without producing a billable test. A request that needs three containers, a specimen that arrives mislabelled and a referral that gets repackaged each take a bag. Modelling a 5 to 10 percent exception allowance is normal; a figure much higher than that points at a labelling or packaging problem.
Does ISO 15189:2022 apply to a small independent laboratory?
It applies to medical laboratories that seek or hold accreditation to it, whatever their size. The standard covers the pre-examination phase, which includes specimen collection and transport, so the bag specification and the receiving record fall inside the quality system rather than outside it.
What should the purchase order specify?
Bag dimensions, the 95 kPa claim with a test report, presence of an integrated absorbent and a document pouch, the UN3373 marking, pack and case quantities, and the minimum remaining shelf life on delivery. Adding the laboratory's average monthly consumption lets the supplier check the case size against actual use.
CliniEco Medical supplies specimen transport and infection-control consumables in Canada under MDEL #35334. This article sets out a planning method and summarises published rules; it is not regulatory advice, and packaging, marking and documentation should be confirmed against the transport regulations and the accreditation standard that apply to the laboratory.
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