4.3 Daily QC, Temperature Logs, and Corrective Action
Key Takeaways
- Daily QC logs record date, time, operator, device, lot numbers, control results, acceptable ranges, and whether each level passed.
- Refrigerator, freezer, room, incubator, and water-bath temperatures—and humidity when the SOP requires it—are logged every day of use against the posted range.
- Out-of-range storage or failed QC: document the actual reading, take corrective action, notify the supervisor, and do not report patient results from an out-of-control system.
- Repeating a control is allowed only when the SOP permits it after a handling error; persistent failure requires troubleshooting and taking the device out of service.
- Never alter a log after the fact or skip an out-of-range entry to keep the sheet looking in range.
CMLA I.2.A.2.e and I.2.A.3 sit together in daily work: know daily quality control and use of results, and maintain temperature and humidity logs, then document and take corrective action when a reading is out of range. This is the paperwork and the stop-work decision that keep a precise-looking number from becoming a reported error.
Quick Answer: Log QC and temperatures every day of use, even when they are in range. If a control, refrigerator, freezer, room, incubator, or water bath is out of range, document the actual reading, take corrective action, notify the supervisor, and do not report patient results from an out-of-control test system or from reagents stored outside their allowed range.
What a daily QC record must capture
A complete daily QC entry is a legal laboratory record. Typical required fields (follow your SOP form):
| Field | Why it is there |
|---|---|
| Date and time | Proves the check happened before (or with) that day's patients |
| Device or kit identity | So a failure can be traced to one meter, analyzer, or kit lot |
| Control name, level, lot number, expiration | Distinguishes "wrong bottle" from a true analytic failure |
| Strip, cassette, or reagent lot | Lot changes are a classic cause of shifts |
| Result and acceptable range | The pass/fail decision must be reconstructable |
| In-range or out-of-range designation | A number without a judgment is incomplete |
| Operator identification | Training and competency trail |
| Corrective action, if any | Required when the result is unacceptable |
| Supervisor review (per SOP) | Release of the device back to service |
Do not leave blanks. Do not write "OK" without the numeric result if the form asks for a number. Do not copy yesterday's values. Electronic QC that stores results still needs the operator to review and accept them before patients.
Use of results is binary at the bench: in control → patients may be tested on that system; out of control → patients are not reported from that system. "The patients are waiting" is not a QC rule. A high-level control that fails is a failed system even if the low-level control passed.
Temperature and humidity logs
Reagents, controls, calibrators, kits, and some analyzers are valid only inside a manufacturer temperature (and sometimes humidity) window. A CMLA commonly logs:
| Equipment | Typical posted range (always use the SOP/IFU number on the unit) | Why it matters |
|---|---|---|
| Refrigerator | Often 2–8 °C for kits, controls, and many reagents | Too warm: reagents degrade and QC begins to trend. Too cold: kits freeze and are ruined |
| Freezer | Often about −20 °C or the narrower range on the unit | Frozen controls that thaw and refreeze can shift |
| Room (ambient) | Commonly about 15–30 °C, kit-specific | Waived cassettes stored on a hot windowsill are off-label storage |
| Incubator | Often 35–37 °C for microbiology or kit incubations the SOP assigns | Under-incubation yields false negatives |
| Water bath | The temperature the SOP names for that bath | A 37 °C kit bath at 32 °C is not the method you verified |
| Humidity | Only when the IFU or SOP requires it (some analyzers and strip canisters) | Excess humidity ruins opened glucose or UA strips |
Those Celsius windows are typical manufacturer and SOP ranges, not numbers AMT prints on the outline. The exam cares that you read the posted acceptable range on that unit and act when the number is outside it.
Read the same thermometer or probe the laboratory designated. Do not eyeball "it feels cold." If the SOP requires twice-daily readings (opening and closing), do both. Record the actual number, not a checkmark, when the form is numeric. Humidity logs appear on some waived chemistry and strip systems and in rooms where opened desiccant canisters sit. If the SOP has a humidity line, it is not optional.
Out-of-range: document, correct, do not hide
When a temperature or QC value is outside the posted range:
- Record the true reading. Writing an in-range number to keep the sheet pretty is falsification.
- Take immediate corrective action within your training. Examples: close the refrigerator door, move kits out of a failed unit into a backup unit that is in range, discard ice-crystal kits if the SOP says they are unusable, remix or replace a control, clean a meter window, remove a device from service.
- Notify the person the SOP names—usually the section supervisor, lead, or laboratory director's designee. Do not wait until the end of the week.
- Quarantine affected materials and results. Reagents stored overnight at 18 °C in a failed refrigerator are not "probably fine." Patient results generated while a meter was out of control are not released.
- Document what you did, who you told, the time, and the follow-up reading that showed the unit or device recovered (or that it was taken out of service).
- Do not resume patient testing until the SOP's release criteria are met (repeat QC in range, temperature restored for the required observation period, supervisor sign-off).
Facilities or biomedical engineering may need to repair a refrigerator. Calling them is appropriate; releasing kits on your own after a 12-hour warm excursion is not.
Repeat versus troubleshooting versus out of service
Stay inside assistant scope.
| Action | When it is appropriate | When it is not |
|---|---|---|
| Repeat the control | SOP allows one repeat after a known handling error (forgot to mix, used expired open-vial dating, obvious air bubble) | Repeating until you get a number you like; deleting the first failure |
| Troubleshoot | New control vial, new strip lot, clean the optic or window, confirm code chip, confirm expiration, verify room temperature | Opening a high-complexity analyzer's fluidics or rewriting calibration factors |
| Take out of service | QC still fails, function check fails, temperature cannot be restored, you are unsure | Leaving a sticky note and hoping the next shift watches it while patients continue |
Taking a waived meter or UA analyzer out of service means labeling it DO NOT USE, unplugging or locking it per SOP, moving patients to a backup in-control device or delaying testing, and notifying the supervisor. You do not independently recertify a hospital core-lab chemistry analyzer, and you do not discard an entire reagent inventory without following the SOP—but you do stop using the failed device.
Who to notify
Notify before you improvise. The usual chain is the immediate supervisor or testing personnel designated in the SOP, then the laboratory director's designee if the supervisor is unavailable and patients are pending. For a building-level failure (the reagent refrigerator at 15 °C at 06:00), also follow the SOP for facilities notification. Public-health reporting of diseases is Chapter 3; this chapter is about internal notification so bad results never leave the laboratory.
Scenarios
At 07:00 the reagent refrigerator reads 12 °C (posted range 2–8 °C). The door was ajar. You record 12 °C, close the door, move unopened kits to the backup refrigerator that reads 5 °C, quarantine kits that the SOP says must be discarded after a temperature excursion, notify the supervisor, and do not run waived chemistry from the warm unit. Glucose-meter controls stored in that refrigerator are not used until the supervisor releases a new in-range set. Patient fingersticks wait or move to a second meter whose controls were stored correctly and run in range.
A second scenario: the incubator's 10:00 reading is 34.0 °C (SOP 35–37 °C). You do not "turn it up and ignore it." You document, adjust only if you are trained to do so, re-read after stabilization, notify, and hold any kit incubations that require that chamber.
A third scenario: daily glucose QC fails, you remix and repeat once because the SOP allows that after a handling error, and the repeat still fails. You clean the port, open a new control bottle, and it still fails. You label the meter out of service. You do not keep repeating until a random in-range number appears, and you do not report the morning clinic patients from that meter.
Exam traps
- Reporting patients because "only the high control failed."
- Back-filling temperature logs from memory at the end of the month.
- Treating a one-time repeat as permission to ignore a persistent trend.
- Assuming a warm refrigerator is only a facilities problem that does not affect reported results.
- Recalibrating a high-complexity analyzer yourself to "fix" a temperature-related shift.
Daily logs exist so that if a result is questioned next week, you can prove the system was in control—or prove that it was not and that you stopped.
The high-level glucose-meter control is outside the printed range; the low-level control is acceptable. What should the assistant do with patient testing on that meter?
The reagent refrigerator reads 12 °C; the posted acceptable range is 2–8 °C. The correct first actions are:
After a waived UA analyzer's QC is still out following the SOP-allowed repeat and basic troubleshooting, the assistant's in-scope action is: