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The testing cycle and patient identity

12 min

  • Locate an error in the preanalytic, analytic, or postanalytic phase
  • Verify patient and specimen identity before testing or giving a result

Read the full reference

Try first

Try first

A potassium comes off the analyzer high. The serum is visibly red, the hemolysis index is raised, and both levels of quality control on the run were acceptable. Where in the testing cycle did the problem begin?

The next section explains it.

The next section explains it.

Right. The next section explains why.

The next section explains it.

Get the idea

Three phases

Every result passes through three connected phases, often called preanalytic, analytic and postanalytic. ISO standards name them preexamination, examination and postexamination. Together they make up the path of workflow, which starts with the patient and ends when the result is reported and interpreted.1

PhaseCoversTypical failures
PreanalyticTest selection, patient identification, collection, labeling, transport and receiptWrong patient, wrong tube, short fill, clot, hemolysis, delay
AnalyticThe measurement itselfFailed quality control, calibration error, reagent or instrument fault
PostanalyticReview, reporting and interpretationTranscription error, wrong reference interval, late critical call

Name the phase where it began

Naming the phase tells you where to look. A problem often shows up in a later phase than the one where it began.

  • Hemolysis is the usual example. The analyzer's index reports it during measurement, and in most cases the red cells broke during collection or transport, so changing reagents or recalibrating fixes nothing.1,2
  • Acceptable quality control shows the measuring system worked. It says nothing about whether one patient's tube was fit to measure.1

Identity at every handoff

The first preanalytic check is identity, and it runs through the whole cycle.

  • A specimen is linked to a patient by at least two person-specific identifiers, such as full name with date of birth or medical record number.3,4
  • A room or bed number never counts, because patients move and rooms are reused.4
  • The label goes on the tube in the patient's presence, with the name, a unique identification number, the collection date and time and the collector's initials.1,3

The same two identifiers are checked again each time the specimen or its result changes hands:3,4

  • at receipt, against the order
  • before testing
  • whenever a result is given out, including by phone

A name alone is one identifier, and two patients in the same hospital can share it. An unlabeled specimen, or one whose label and request do not match, is rejected under the laboratory's identification policy. The requester is told promptly, and a new specimen is requested.1

References
  1. World Health Organization. Laboratory Quality Management System: Handbook. World Health Organization; 2011:11,65-66. Accessed September 23, 2026.
  2. Simundic AM, Bölenius K, Cadamuro J, et al. Joint EFLM-COLABIOCLI recommendation for venous blood sampling. Clin Chem Lab Med. 2018;56(12):2015-2038. doi:10.1515/cclm-2018-0602
  3. Clinical and Laboratory Standards Institute. Patient and Laboratory Specimen Identification Processes. 1st ed. CLSI standard PRE01. Clinical and Laboratory Standards Institute; 2024. Accessed September 23, 2026. https://clsi.org/shop/standards/pre01/
  4. The Joint Commission. Two patient identifiers: understanding the requirements. Updated April 21, 2026. Accessed August 28, 2026.

Watch one

An outpatient serum collected at a clinic at 09:00 reaches the laboratory unspun at 15:30.

  • Potassium is high and glucose is low.
  • The hemolysis index is not raised.
  • Both control levels on the run were acceptable, and calibration is current.

Where did the error begin?

  1. Check the analytic evidence: both controls acceptable and calibration current, so the measuring system worked on this run.

    The run's QC and calibration records settle the analytic question quickly.

  2. Check the indices: hemolysis is not raised, so hemolysis does not explain the potassium.

    A raised potassium on red serum would point to broken red cells.

  3. Read the collection and receipt times: six and a half hours with serum sitting on its cells.

    Time and handling records show what happened to the tube before it was measured.

  4. Match the pattern: a high potassium with a low glucose fits delayed separation.

    Cells left in contact with serum keep using glucose and let potassium leak out.

  5. The error arose before measurement: preanalytic. Apply the laboratory's stability limit and request a new specimen.

    The phase is named for where the error began, which is also where the fix belongs.

A preanalytic error: delayed separation during transport.

Your turn

Problem 1 of 3

Which pair of identifiers is suitable for matching a specimen to the patient?

Incorrect. A room number describes a location, and patients move between rooms. The second identifier has to belong to the person, such as a date of birth or medical record number.

Correct. The name and the medical record number both belong to the patient, so they are two person-specific identifiers, and the label keeps them linked to the specimen through testing.

Incorrect. One identifier checked in two places is still one identifier. Two patients who share a name would both match.

Hint
  1. An identifier has to belong to the person, wherever they are.
  2. A room number describes a place, and a patient can move rooms.
  3. Look for the pair made of two different facts about the person.

Review Ordering, identification, and acceptability

Problem 2 of 3

Which finding points to a problem in the analytic phase?

The analyzer detects the hemolysis. The red cells broke during collection or transport, which makes it a preanalytic problem.

Called collection hemolysis an analytic error

Most hemolysis begins as the specimen is collected or transported, and the analyzer reports it as an index during measurement. Filing it as an analytic error sends the investigation to reagents and calibration and leaves the collection practice that caused it unchanged.

The measurement was finished and verified, so the delay came in reporting, which is postanalytic.

Controls test the measuring system. When both levels fail together, the fault lies in the measurement: reagent, calibration or instrument.

Hint
  1. The analytic phase is the measurement itself.
  2. Ask which finding shows the measuring system misbehaving, whatever specimen is on it.

Review The testing cycle

Problem 3 of 3

A nurse on 5 West phones for the hemoglobin of patient Dana Okafor. The laboratory system shows two inpatients named Dana Okafor, one on 5 West and one on 3 East. What do you do before giving a result?

Two person-specific identifiers link the call to one patient. Only when both match the record do you give the result.

A unit is a location, and patients move between units. Location cannot tell two patients with the same name apart.

A name is one identifier, and here it matches two patients. The result could go to the wrong person's care.

Matched a result to a patient by name alone

A name is one identifier, and two patients can share it. Giving or filing a result after matching the name alone can place one patient's value in another's record or give a caregiver the wrong result. Two person-specific identifiers, such as name with date of birth or medical record number, link a specimen to one patient.

That gives out a second patient's result and leaves the choice to guesswork. Confirm identity first, then give one result.

Review Ordering, identification, and acceptability

Use it

Try this at the Chemistry stationPendingResult pending review1AWAITING VERIFICATIONHemolysis: decide assay by assayReview results

Keep

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