A blood sample is processed, and the resulting serum is pink. This indicated:

• a. a normal serum sample.

• b. a hemolyzed serum sample, but hemolysis is common and can be ignored.

• c. a hemolyzed serum sample, which may adversely affect testing.

• d. definite evidence of bacterial contamination.

To process a whole blood sample to produce serum, the sample must:

• be spun in a centrifuge immediately after drawing.

• sit at room temperature to allow time to clot before spinning.

• be placed in a freezer to allow time to clot before spinning.

• be placed in a heat block as soon as possible.

A blowout pipette would be labeled:

• TD.

• TC.

• ML.

• SD.

When 0.5 mL of serum is added to 1.5 mL of diluent, what dilution does this represent?

• 1:3

• 1:4

• 1:5

• 3:1

If you want to make 4 mL of a 1:20 dilution, how much serum would be needed?

• 0.2 mL

• 2 mL

• 0.5 mL

• 1 mL

How should a 1:50 dilution be made if the final volume needed is 10 mL?

• 0.1 mL of serum and 9.9 mL of diluent

• 0.2 mL of serum and 9.8 mL of diluent

• 0.2 mL of serum and 10 mL of diluent

• 0.5 mL of serum and 9.5 mL of diluent

You start with a 1:2 dilution then create three subsequent 1:10 dilutions. What is the ending dilution?

• 1:200

• 1:220

• 1:2000

• 1:2200

A new assay is used to test 120 samples from patients with a clinically confirmed diagnosis of the relevant infection and 50 samples from healthy control subjects. The test results were positive for 90 of the infected patients and positive for 10 of the healthy controls. What is the sensitivity for the assay?

• 57%

• 75%

• 80%

• 90%

A new assay is used to test 120 samples from patients with a clinically confirmed diagnosis of the relevant infection and 50 samples from healthy control subjects. The test results were positive for 90 of the infected patients and positive for 10 of the healthy controls. Calculate the positive predictive value of the assay.

• 57%

• 75%

• 80%

• 90%

The probability that a person with a positive screening test actually has the disease screened for is called:

• sensitivity

• specificity

• positive predictive value

• negative predictive value