Laboratory Activity 4 – Specimen Collection and Processing Flashcards
Basic to laboratory testing are the
proper identification, collection, and processing of the specimen.
is the general specimen collected, which is then processed to serum
blood
may also be used for serologic testing
other biologic fluids
is often prepared in the serology laboratory and used as an indicator reagent to agglutination reaction or complement fixation
red cell suspension
T or F
Various factors affect the accuracy of testing and reliability of results; it is, therefore, essential to avoid these sources of errors during the collection and processing.
TRUW
is crucial in ensuring production of quality test results
knowing the nature of the specimen and reagent
most frequently encountered specimen in the immunology-serology laboratory is
serum
the scientific study or diagnostic examination of blood serum
serology
Blood specimens are collected through
venipuncture procedures (syringe or evacuated tube method)
can be used in immunology-serology tests
Glass red-top tubes (plain) or plastic red-top (with clot activator)
specimen of choice for all antibody screening methods
serum derived from clotted whole blood
are unacceptable because the additives can interfere with the serum screen assay
Specimen tubes with clot activators and serum separators
Glass red-top tubes usually take about [?] for plastic red-top tubes to completely clot.
60 minutes and 30 minutes
Care must be taken to avoid hemolysis, since this may produce a false-positive test result.
SERUM
Allow [?] before centrifugation, and serum should be promptly separated into another tube without transferring any cellular elements.
complete clotting
However, if the serum is contaminated with erythrocytes, it should be
re-centrifuged
Serum samples that are allowed to sit [?] are likely to retain cellular elements and other contaminants that will have an impact on future analysis.
less than 30 minutes
Samples that sit longer than [?] are likely to experience lysis of cells in the lot releasing cellular components not usually found in serum samples.
60 minutes
If testing cannot be performed immediately, serum may be stored between [?].
2°C and 8°C for up to 72 hours
If there is any additional delay in testing, the serum should be frozen at
–20°C or below
Always observe the [?] of specimens.
complete and proper labeling
is the process that destroys complement activity.
Inactivation
is known to interfere with the reactions of certain syphilis tests
Complement
can agglutinate latex particles and cause a false-positive reaction in latex passive agglutination assays
Complement
may also cause lysis of the indicator cells in hemagglutination assays.
Complement
is intended to inactivate serum complement.
Heating serum
This is done by placing serum samples (in a properly labeled test tube) in a water bath set at 56°C for 30 minutes.
Heating serum
When more than 4 hours have elapsed since inactivation, a specimen can be re-inactivated by heating to
56°C for 10 minutes
often utilized an indicator reagent to selected agglutination reactions or complement fixation tests
Red cell suspension (RCS)
Red cell suspensions prepared from clotted samples should be [?], and suspensions prepared from freshly anticoagulated samples should be [?], both of which could lead to false results
free of clots
free of fibrin
Red blood cells suspended in a liquid medium such as normal saline solution (NSS) should be between [?] for standard tube agglutination tests, with an ideal strength of about [?]
2% and 5%
3%
Procedure in the Preparation of 2-5% Red Cell Suspension
a. Transfer carefully [?] of the whole blood or packed red blood cells from plasma preparation into a graduated centrifuge tube
b. Washing phase:
(1) Add normal saline solution (NSS) up to the [?] mark of the centrifuge tube
(2) Cover the mouth of centrifuge tube using Parafilm, then mix by gentle inversion, [?]
(3) Centrifuge the tube for [?], discard the supernatant fluid using a Pasteur pipette, leaving the red blood cells.
(4) Repeat steps [?]two or three more times until the supernatant is clear.
c. After the final washing, note the volume of the washed packed red blood cells (WPRBC) before the supernatant is completely removed by [?].
d. Compute for the [?] and the [?] to be added to the washed red blood cells to come up with the desired concentration (in %) of the RCS using the derivation and formula
a. <1.0 mL
b.
1. 10 mL
2. 2-3 times
3. 5-10 minutes at 2,500 rpm
4. 1 ® 2 ® 3
c. aspiration
d.
- total volume (TV) of the RCS preparation
- volume of the diluent (NSS)
e. From the total volume computed (TV), determine the volume of the diluent to be added to the washed packed RBC (WPRBC) by using the following derivation and formula:
f. Add the appropriate volume of [?] to the [?] to prepare the desired concentration (in %) of the RCS
NSS
WPRBC
g. The suspension is mixed thoroughly to produce a [?]. Check for the presence of clots in the suspension.
homogenous solution
h. Label the RCS according to the
concentration, blood (antigen) type, and preparation date
