Question

You are working in the coagulation department after service has just finished doing a 6 month preventive maintenance (PM) check on the coag analyzer that includes removing all current data in the analyzer. After the PM check, you run quality control (QC) for prothrombin time (PT) and activated partial thromboplastin time (aPTT). The QC for the aPTT is within 2 SD but the PT control is outside of 6 SD. In troubleshooting, what might the problem be?

Select one:
a. QC after maintenance is not really needed so if the pre maintenance QC is okay, then you can continue with patient testing.

b. The ISI value that is currently in the instrument was set back to zero after maintenance and needs to be re-entered before patient testing is resumed.

c. The controls must be contaminated so make up new controls and re-run just the PT test.

d. It is normal for the PT to change after a preventive maintenance, so the range for the
QA will need to be changed.

Answer 1

The most likely issue after PM on a coagulation analyzer that results in PT control being outside 6 SD is the reset of the ISI value, which needs to be re-entered correctly for accurate test results.

Step-by-step explanation:

When troubleshooting the issue in a coagulation department where quality control (QC) for prothrombin time (PT) is outside of 6 standard deviations (SD), several factors need to be considered. Since the QC for activated partial thromboplastin time (aPTT) is within 2 SD, this suggests that the maintenance procedures may have specifically affected the PT test system. The problem could be attributed to changes in the calibration settings such as the International Sensitivity Index (ISI) value, which may have been reset or modified during the preventive maintenance. It is essential for the ISI value to be correctly entered to ensure accurate PT results. Option (b), which identifies the need to re-enter the ISI value, is the most probable cause for the discrepancy observed. It is not correct to assume that maintenance will invariably alter the PT range (option d), and it is a requirement to perform QC after maintenance (opposing option a), so skipping QC is not advisable. Similarly, assuming the controls are contaminated without further evidence is premature (option c).