Chain of custody and labelling

Why it matters

A perfect test on the wrong patient's blood is worse than no test at all. Identification errors can lead to a missed diagnosis, the wrong treatment, or, in the blood bank, a fatal transfusion reaction. Labelling and tracking are how a lab proves that this result belongs to this patient and that the specimen was handled correctly at every step.

Safety and scope. This lesson and its activity are paper exercises with fictional patients. Real specimen collection and handling happen only in supervised clinical training or employment, after bloodborne-pathogen training. Never use real patient information for practice: it is protected health information.

Patient identification

Before any collection, the collector confirms identity with at least two patient identifiers, such as full name and date of birth or medical record number. The room number is never an identifier. In hospitals, the collector compares the patient's spoken answers (when possible) and wristband with the requisition. Patient-safety goals published by accreditors such as The Joint Commission make two identifiers a baseline requirement.

What goes on the label

Each tube is labelled at the patient's side, immediately after collection, never in advance. A typical label carries:

• Patient full name and a second identifier (date of birth or record number).
• Date and time of collection.
• Collector's initials or ID.
• A barcode linking to the order (the accession number) in the laboratory information system (LIS).
• For non-blood specimens: the source (for example "urine, clean catch" or "wound, left heel").

Barcoded labels printed at the bedside reduce transcription errors. The LIS records each scan, so the lab can see when a specimen was collected, received and tested.

Tracking inside the lab

Once received, the specimen is accessioned: scanned in, checked against the order, and given a status. Aliquots (portions poured into secondary tubes) get their own labels that link back to the primary tube. Every move (centrifuge, analyser rack, refrigerator, send-out box) should be traceable. When something goes wrong, this trail is how the lab finds out where.

Chain of custody

Some specimens are evidence: workplace drug tests, forensic samples, some paternity tests. For these, the lab follows a formal chain of custody (CoC): a documented, unbroken record of everyone who handled the specimen, from collection to final disposal. Typical features:

• A CoC form with a unique specimen ID that matches the label.
• A tamper-evident seal applied in front of the donor, who initials it.
• A signature, date and time for every transfer between people or locations.
• Secure, access-controlled storage.
• Any broken seal or gap in signatures is documented and may make the result unusable.

Environmental and food testing labs use chain of custody too, so this skill transfers across lab careers.

Worked example: auditing a batch

You are the reviewer for four fictional labels:

And one chain-of-custody form: the seal was applied at 09:02 by the collector, the courier signed at 09:40, and the lab signed receipt at 11:15, but no one signed for the 10:30 hand-off to the overnight fridge. That gap must be documented; depending on the program's rules, the specimen may be reported as unsuitable.

Common mistakes

• Pre-labelling tubes before the draw (the classic route to a wrong-blood-in-tube error).
• Using room or bed numbers as identifiers.
• Leaving the source off microbiology specimens.
• Letting a courier sign "for" another person on a CoC form.

Quick recap

• Two identifiers, confirmed with the patient, every time.
• Label at the patient's side right after collection, with time and collector.
• The LIS accession and barcode link every aliquot back to the order.
• Chain of custody is an unbroken, signed record from collection to disposal.

Try it

Open the Do tab. You will design a label and a chain-of-custody record on paper and audit them for gaps.