Préanalytique Flashcards
(77 cards)
- Which blood specimen, in a multi-draw situation, most closely represents the composition of circulating blood?
a) The blood drawn first
b) The final tube drawn
c) Only the serum tubes
d) Only the plasma tubes
A
A blood collection tube containing sodium fluoride and an oxalate inhibits coagulation by:
a) binding calcium, which is essential or the clotting mechanism
b) accelerating the action o antithrombin III
c) forming insoluble complexes with calcium ions
d) inhibiting the enzyme systems involved in glycolysis.
A
Why is pumping the fist before venipuncture inappropriate for blood collection?
a) It causes venous stasis
b) It causes increased potassium, lower blood pH, and increased ionized calcium
c) It causes increased plasma concentrations of cortisol and growth hormone
d) It leads to premature separation of serum and brin clot formation.
B
One of the best and most acceptable methods of preserving a urine specimen is:
a) Thymol
b) Refrigeration
c) incubation at 37 °C
d) phenol.
B
To allow or early diagnosis of an inherited genetic disorder at a gestational period of 10 to 12 weeks, the best specimen is:
a) saliva
b) synovial fluid
c) amniotic fluid
d) chorionic villus sampling.
D
After centrifugation, plasma or serum is best separated from cells:
a) within two hours
b) within six hours
c) within twelve hours
d) when it is convenient for the laboratorian.
A
The difference between serum and plasma is that:
a) plasma contains all of the cellular elements of blood (WBCs, RBCs, etc.), but serum does not.
b) plasma contains none of the clotting actors
c) serum is obtained by mixing anticoagulants with whole blood.
d) serum is obtained when whole blood is allowed to clot and then is centrifuged.
D
Hemolysis is defined as:
a) increased lipids in the blood that give the serum a milky appearance.
b) excess bilirubin in serum that give it a greenish-yellow appearance
c) plasma that has been allowed to clot over time
d) damage to red blood cell membranes leading to release off the contents of red cells into the plasma.
D
An evacuated blood collection tube with a light blue stopper contains which of the following additives?
a) Heparin
b) EDTA
c) Sodium citrate
d) Sterile media or blood culture
C
- An example of a controllable preanalytical variable or laboratory testing would be:
a) Diet
b) Sex
c) Age
d) underlying disease.
A
. Identify the incorrect scenario related to specimen collection below.
a) Ask a parent to name a pediatric patient
b) Ask an adult patient to state his or her name and another identifier
c) Show the patient or parent the labeled tube after collection is complete
d) Check the room and bed number of the patient to be collected and proceed with collection
e) Per any local policy, contact a translation service if your patient has been identified either in the electronic system or personally as non–local speaking.
D
Identify the correct tube (additive)/biochemical action below:
A. Lavender (EDTA)/anticoagulated specimen that will limit effects on cell morphology
B. Light blue (ACD)/chelation of calcium to allow effective coagulation testing
C. Red (no additive, no gel)/serum sample that can be sampled directly by many analyzers
D. Light green/no gel/sodium–heparin tube that can be used to prevent any further cellular activity that might affect analytes such as glucose
A
Patients should be cautioned against pumping their fists after the tourniquet is applied because
A. it may or may not cause venous stasis, which is not under the control of the collector.
B. it will affect the chemical interaction between the additive in the tube and the patient’s blood.
C. metabolic activity of the blood and muscles will affect analytes such as potassium and calcium through effectson pH and possibly creatine kinase.
D. it will affect the distribution of analytes between plasma and serum.
E. it will make it more difficult to find the patient’s vein.
C
For urine collections, which of the following is true?
A. Samples should be kept at room temperature for a timed collection.
B. Special identification of the patient may be required for forensic purposes.
C. Identification of added preservative does not need to be communicated to the patient because all are safe.
D. For a 24-hour collection, the patient may collect into a rinsed milk jug and then pour the sample into the provided container at the end of the collection period.
E. No special handling is required because of collection preservative if the sample is sent to another laboratory.
B
Additional testing requested by the clinician treating the patient (add-on testing) should always be carried out, when
A. the sample was not stored correctly per local validated storage policies.
B. the patient is not identified correctly.
C. the request is for a labile compound that may have been affected by storage (eg, glucose when plasma has not been separated from cells).
D. the sample needs to be retrieved from a waste container.
E. the request is for a test that has been validated on the sample submitted.
E
Définit le terme anticoagulant.
Substance qui empêche le sang de coaguler.
Définit le terme variable préanalytique controlable
Facteurs contrôlables pouvant affecter le spécimen avant que les tests soient effectués.
Définit le terme hémolyse
Dommage à la membrane des globules rouges qui induit la libération de l’hémoglobine et autres composantes des cellules.
Définit le terme phlebotomie
Ponction de vaisseau sanguin pour collecter le sang.
Définit le terme plasma
Partie liquide du sang total (non coagulé). Contient donc les facteurs de coagulations.
Définit le terme sérum
Partie liquide du sang obtenu après coagulation et centrifugation.
Définit le terme véniponcture
Toutes les étapes impliquées dans l’obtention approprié et l’identification d’un échantillon de sang obtenu à partir d’une veine d’un patient.
List the general effects on analytes caused by pumping a fist before venipuncture:
Élévation du potassium, du pH et du calcium ionisé
List the general effects on analytes caused by stress:
Élévation cortisol, glucose, hormones de croissance et serum activities of enzymes, adrenal stimulation
