Lab Data: Preanalytical Errors

What is the fluid component of blood that remains after coagulation?

Which of the following blood tests typically requires a red top tube?

Which of the following substances is strongly chelated by EDTA?

Which of the following anticoagulants is found in a blue top tube?

What type of error is hemolysis considered in laboratory testing?

In blood collection, why are larger veins preferred over smaller veins?

What is a potential consequence of a prolonged blood draw time?

What is the primary purpose of using a Vacutainer system in blood collection?

If blood is allowed to clot, which of the following components is consumed?

Which of the following is a potential problem caused by over- or under-filling a collection tube?

What can result from forcing a blood sample through a needle into a collection tube?

What is the purpose of calibrators and controls in laboratory assays?

Which of the following is an example of a post-analytical error?

What is the significance of establishing rejection criteria for laboratory samples?

What is the primary reason for a laboratory to establish its own reference intervals?

If a laboratory has too few healthy animals available to determine a reference interval, what is the alternative?

What is a diagnostic cut-off?

Age and breed are MOST LIKELY to affect reference intervals for which analyte?

Which situation MOST LIKELY indicates that a change in a test result may be significant?

Which of the following represents how sensitivity is calculated?

How is specificity defined in the context of diagnostic testing?

Which calculation determines the efficiency (accuracy) of a diagnostic test?

What effect do sensitivity, specificity, and disease prevalence have on predictive values?

Given the values: Sensitivity = a/(a+c) = 6/27 = 22.2%, Specificity = d/(b+d) = 966/973 = 99.3%. What is the Positive Predictive Value?

If a test has 100% specificity, but lower sensitivity, which of the following is likely?

Which is generally considered a better characteristic for a screening test?

What is a key attribute of a test with high specificity?

What is a potential issue when using outdated reagents in an analytical assay?

In the context of diagnostic testing, what does a 95% specificity indicate?

Which preanalytical error can MOST LIKELY result in an elevated potassium level in a serum sample?

A new diagnostic test shows a high degree of sensitivity but a low degree of specificity. Which of the following statements is true?

A lab is evaluating a new assay for canine parvovirus. The assay correctly identifies 98 out of 100 known positive samples and correctly identifies 95 out of 100 known negative samples. Assume the prevalence of parvovirus in the patient population is approximately 10%. What is the approximate positive predictive value (PPV) of this new assay?

A veterinarian is evaluating two different laboratory tests for detecting Lyme disease in dogs. Test A has a sensitivity of 95% and a specificity of 80%, while Test B has a sensitivity of 80% and a specificity of 95%. In a region where Lyme disease is relatively rare (prevalence of 5%), which test would likely have a higher negative predictive value (NPV)?

A Veterinary practice is using vendor X consumables for a chemistry analyzer using species-specific reference ranges. One month later, Vendor Y consumables are erroneously delivered and used. If Quality Control indicates test results are accurate, what error(s) could STILL occur in patient samples?

Which type of error is LEAST likely to be controlled by a veterinarian when sending samples to a reference laboratory?

What is the MOST LIKELY consequence of using a small vein for blood collection, especially when using a syringe?

Why is serum protein concentration typically lower than plasma protein concentration?

What is the function of the gel in a serum separator tube (SST)?

For which of the following tests would the use of a serum separator tube (SST) be LEAST appropriate?

Which of the following best describes the mechanism by which EDTA prevents blood coagulation?

A blood sample collected in an EDTA tube yields a falsely low calcium level and a falsely high potassium level. What is the MOST LIKELY explanation for these erroneous results?

Why is lithium heparin preferred over sodium heparin for chemistry profiles that include electrolyte measurements?

Which of the following anticoagulants allows for coagulation testing after the addition of calcium?

A blood sample is collected into a gray top tube. What substance in this tube is designed to prevent the consumption of glucose by cells?

What is the expected effect on glucose measurements if a blood sample sits at room temperature for an extended period?

Which of the following describes the MOST appropriate handling of a blood sample for accurate glucose measurement?

What is the effect of hemolysis on the measurement of intracellular constituents, such as AST and LDH?

How does lipemia MOST LIKELY interfere with hemoglobin measurement in a blood sample?

What action should be taken if a laboratory instrument returns a test result that exceeds the assay's linearity?

How do calibrators and controls differ in their use in a clinical laboratory?

Which factor is the MOST LIKELY to influence differences in reference intervals between two different laboratories?

What statistical measure is MOST appropriate for establishing a reference interval when the data set does NOT follow a normal distribution?

Why is it still important to consider reference intervals when evaluating lab results, even with "diagnostic cutoffs"?

What is the BEST course of action if an otherwise healthy adult patient falls just outside the reference interval?

What is the definition of 'sensitivity' in the evaluation of a diagnostic test?

A test with high specificity will produce which of the following?

Using a cutoff that increases the sensitivity of a diagnostic test will result in which of the following?

What is the MOST important characteristic of a test used for initial screening?

In which species is EDTA LEAST suitable as an anticoagulant for hematology due to the lysis of red blood cells?

What hematological parameter is LEAST reliant on instrument accuracy?

Which methodology is MOST subject to inaccuracy due to cell types present in the sample?

Which of the following is MOST dependent on laser scatter?

What is the PRIMARY advantage of flow cytometry over impedance cell counters in performing a complete blood count?

Which component is measured using a refractometer when assessing plasma protein levels?

What causes an artificially high plasma reading on a refractometer?

If a blood sample measured 7.5 g/dL before heat precipitation and 7.0 g/dL after heat precipitation, what would be the value?

Which acute phase protein is commonly measured in dogs to detect inflammation?

Which of the following cell types are stained with Phloxin B?

How is the absolute count of a specific type of white blood cell calculated from a CBC?

Which potential error is MOST mitigated by manual microscope review of blood smears?

A blood sample has a hematocrit of 45% and a hemoglobin concentration of 8 g/dL. What does this indicate?

After performing a manual hemocytometer count on avian blood stained with Nadherix, you have two options regarding manual microscope adjustment. If you only perform Adjustment A, what is the MOST LIKELY end result of this adjustment?

Which artifact contributes most to overestimation of the value of spectrophotometrically measured hemoglobin via a complete blood count (CBC)?

Which type of laboratory error is MOST directly controlled by the veterinarian?

Why might a jugular vein blood sample be preferred over a sample from smaller veins?

What is the primary concern when there is a delay in transferring a blood sample from a syringe to an anticoagulant tube?

What can happen if a blood sample is forcefully pushed from a syringe into a collection tube?

Why is it essential to allow a blood sample in a serum separator tube (SST) to clot fully before centrifugation?

For which of the following analytes is the effect of delayed processing of a blood sample MOST critical?

What is a potential consequence of a delay in separating serum from blood cells?

What is the MOST LIKELY effect of lipemia on a spectrophotometric assay for hemoglobin?

What is the appropriate course of action if a test result exceeds the analytical linearity of the instrument?

A veterinary technician forgets to run controls on the in-house chemistry analyzer for two weeks. What error is MOST LIKELY to occur?

How does dehydration typically affect analyte concentrations when interpreting a chemistry profile?

Why is understanding the influence of percentages crucial in CBC interpretation?

What is the BEST approach when evaluating a laboratory test result for an individual patient?

What characteristic should a veterinarian prioritize when selecting a diagnostic test for initial screening purposes?

Which of the following adjustments will increase the number of false positives?

A test has a high degree of sensitivity. What does this imply regarding negative results?

Which of the following is the correct formula for calculating test accuracy?

Which of the following is the MOST important consideration when interpreting laboratory results from a greyhound compared to other breeds of dogs?

In what circumstance is lithium heparin preferred over EDTA as an anticoagulant for hematology?

What aspect of blood cell analysis is MOST enhanced by flow cytometry compared to impedance cell counting?

What is being measured using a refractometer when assessing plasma protein levels on a routine CBC?

A blood smear from a dog shows a predominance of immature neutrophils (band neutrophils). Which of the following is MOST LIKELY overlooked when relying solely on automated cell counts?

Which BEST explains the use of the absolute count (versus percentage) of a specific type of white blood cell?

Which of the following is the MOST common reason to perform a manual white blood cell count?

A dog has a hemogram performed at a veterinary clinic. The pathologist reports a calculated hematocrit lower than the packed cell volume that was manually assessed. What common pre-analytical error should be FIRST suspected?

What does a mean cellular hemoglobin concentration (MCHC) above the reference interval indicate?

What BEST describes the clinical utility of measuring acute phase proteins, such as C-reactive protein (CRP) in dogs?

An otherwise healthy dog has an elevated blood glucose. How may a serum separator tube reduce glucose consumption?

During blood collection from a cat, the vein collapses, resulting in a prolonged draw time. What is the MOST LIKELY consequence of this pre-analytical error on the complete blood count (CBC)?

A veterinary technician is tasked with measuring fibrinogen concentration using heat precipitation. Upon performing the test, it is observed that the sample was hemolyzed before heat precipitation. What error will this MOST LIKELY introduce?

Which BEST describes the purpose of analyzing clinical data using non-parametric statistics?

Which of the following clinical parameters is LEAST reliant on the proper functioning of a hematology analyzer?

Which scenario is LEAST LIKELY to cause a falsely low hematocrit?

Which anticoagulant LEAST reliably prevents platelet clumping?

Which cell population should NEVER be circulating in peripheral blood?

Why is lyse added to an aliquot of a hemogram sample prior to assessment on some machines??

When comparing positive predictive value (PPV) and negative predictive value (NPV), what consideration is MOST important?

A hospital runs internal Quality Control which indicates that the spectrophotometer consistently under-reports hemoglobin. How will this affect measurement of MCHC?

A novel assay is developed to detect infection with Canine Wunderpeste, with a sensitivity of 65% and a specificity of 90%. If the disease prevalence in the screened population is 5%, what is MOST accurate description of this assay's use?

Which would BEST correct manual hemocytometer results after observing that the sample chamber was overfilled?

Which of the following best describes a pre-analytical error in laboratory testing?

What is the MOST direct way a veterinarian can influence the accuracy of laboratory results before sending a sample to an outside reference lab?

Why might a jugular vein be preferred over a peripheral vein for blood collection when performing a coagulation panel?

What is the primary difference between serum and plasma?

What is the KEY purpose of the gel in a serum separator tube (SST)?

For which analyte is immediate processing of a blood sample MOST critical to prevent clinically significant changes?

A blood sample is collected into a purple top tube. If a chemistry profile is inadvertently run on this sample, which analyte is MOST likely to be falsely decreased?

What is the purpose of sodium fluoride in a gray top blood collection tube?

Lipemia can falsely increase which analyte when measured spectrophotometrically?

What is hemoconcentration, and how does it relate to analyte concentrations?

In the context of hematology, what is the significance of the absolute count of a specific type of white blood cell compared to its percentage?

A dog has a calculated hematocrit that is lower than the packed cell volume determined manually. What is the MOST LIKELY cause of this discrepancy?

You have a leukopenic sample but need 100 white blood cells to enumerate under the microscope. What area under the microscope contains the MOST accurate representation of white blood cell morphology?

What does an elevated Mean Corpuscular Hemoglobin Concentration (MCHC) MOST LIKELY indicate?

Why are species-specific assays required when measuring acute phase proteins, such as C-reactive protein (CRP)?

Following collection of a blood sample, why is a sample spun into a serum separator tube?

Which of the following situations would LEAST LIKELY cause a falsely low packed cell volume (PCV)?

What is the MAIN reason to look at a blood smear during a complete blood count?

Which of the following best describes how impedance analyzers differentiate cell types?

What is the primary method by which flow cytometry identifies and counts cells in a blood sample?

How does forward light scatter differ from side light scatter in flow cytometry?

Which of the following is a limitation of hematology instruments when analyzing blood samples from birds and reptiles?

What is a key reason why a microscopic examination of a blood smear is important, even when using an automated hematology analyzer?

What is the clinical significance of measuring fibrinogen by heat precipitation in large animals?

Which of the following is a potential source of error when using a refractometer to measure total plasma protein?

What condition would LEAST LIKELY cause an increase in fibrinogen levels?

After heat precipitation, the difference between the uncooked total protein and the cooked total protein is 0.6 g/dL. What does this value represent?

What is the primary advantage of performing manual cell counts using a hemocytometer?

Which of the following statements BEST describes the purpose of performing a manual white blood cell differential count?

Which of the following situations would MOST warrant performing a manual cell count?

When performing a manual white blood cell differential count, how are nucleated red blood cells (NRBCs) accounted for?

How does platelet clumping affect automated platelet counts, and what is the best method to assess platelets when clumping is present?

What does an increased mean cell hemoglobin concentration (MCHC) typically indicate?

Apart from inflammation, which factor can increase fibrinogen concentration?

In impedance analyzers, what causes the voltage pulse that is proportional to cell size?

When should a manual differential count be performed to correct the WBC counts on the instrument?

Which factor has the LEAST impact on the accuracy of hematocrit measurements using automated instruments?

While performing hematology for a patient, you get a CBC report with a higher than expected hemoglobin (Hgb) level. What should you suspect?

Why is microscopic evaluation necessary when an instrument is used to perform a differential count of white blood cells?

What part of a sample do you look at when performing microscopic evaluation of blood smears?

Which of the following is a disadvantage of using impedance analyzers?

After performing a manual cell count, it is noted that the hemacytometer chamber was overfilled. What would be the MOST appropriate course of action?

A CBC from a reptile sample yields inaccurate results on the in-house analyzer. What would be your next step?

A canine blood sample tested on an impedance analyzer returns a normal WBC count, but the blood smear shows a high number of atypical lymphocytes. Which statement is MOST accurate?

Which type of error is LEAST likely to be identified by running daily controls on an automatic cell counter?

Which acute phase protein will increase 10-1000x with inflammation?

Which of the following is NOT an advantage of manual cell counts?

How does flow cytometry differentiate cell populations?

What would be MOST indicated if the automated hematocrit value is lower than that of the packed cell volume (PCV) after centrifugation?

What information can be gained by a veterinary paraprofessional upon gross evaluation of collected blood samples after centrifugation?

What parameters on a complete blood count (CBC) require calculation?

While analyzing a patient sample, lipid droplets are included in automated processes, which result do you suspect?

In impedance instruments, which cells are identified in aliquot #1?

In which of the following patients is a veterinary instrument considered less accurate?

A novel, automated hematology analyzer boasts the ability to distinguish cell types based on over 50 different parameters. Which drawback is LEAST likely minimized with use of this analyzer?

What calculation is required when correcting for circulating nucleated red blood cells (NRBCs) in a complete blood count (CBC)?

What is the typical effect of delayed analysis on a blood sample, and is this effect consistent in all species?