Author Question: The tubing that brings the lyse reagent to the hemoglobin cuvette on an automated cell counter is ... (Read 139 times)

abarnes · **on:** Jun 25, 2018

The tubing that brings the lyse reagent to the hemoglobin cuvette on an automated cell counter is pinched and not delivering any reagent. All hemoglobin values are greater than 20 g/dL. This represents what type of error?

a. Random
b. Imprecision
c. Constant systematic
d. Proportional systematic

Question 2

One of two controls that have been evaluated over the last 28 days gives a result on day 29 between 2 and 3 SDs of the mean; the other control is within 2 SDs of its mean. What is the correct procedure to follow?

a. Ignore the result unless it happens again the next day.
b. Rerun the control and if acceptable continue with patients.
c. Recalibrate the instrument.
d. Open new vials of controls and repeat both controls.

AmberC1996 · **Reply #1 on:** Jun 25, 2018

Answer to Question 1

ANS: C
A constant systematic error is one in which the magnitude of the error remains the same throughout the range of the test measurement. The error is proportional if the magnitude varies relative to the result. This is not a random error, which happens only infrequently and is not predictable. Precision requires multiple measurements of the same specimen and evaluates the ability to consistently reproduce the result.

Answer to Question 2

ANS: B
One control is acceptable, whereas the other is a warning that the method may be going out of control. The test option in this case is to repeat the analysis of the control, and if it is acceptable, then continue with patient analysis, reporting the results. The instrument does not appear to need recalibration because one control is acceptable and the other is within 3 SDs (1 result of 20 can acceptably be within 3 SDs). If the repeat on the out of control vial is still out between 2 and 3 SDs, then a new vial of that control should be opened and analyzed. The control that was acceptable does need to be repeated.