Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display Chapter 51 Booth, Wallace, and Fitzgerald PowerPoint Presentation.

Chapter 5 1

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display

Booth, Wallace, and Fitzgerald

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Chapter 5 2


Specimen Processing

Chapter 5 3


ObjectivesUpon completion of this chapter, you should be able to:

•List requirements for special specimen handling procedures.

•Describe the technique required for collecting blood cultures.

•List the steps for Unopette® collection.

•Describe the procedure for performing a microhematocrit.

Chapter 5 4


Objectives cont’d•Explain the collection process and

procedure for making a peripheral blood smear.

•Discuss common point-of-care and CLIA waived tests.

•Explain the procedure for urine specimen collection and reagent testing.

•Identify safety requirements for operating a centrifuge.

Chapter 5 5


Special Handling ProceduresIn addition to blood collection, some specimens require special handling either before or after the blood is collected.

Common Tests Requiring Special Handling Procedures

BloodCultures

Cold AgglutininsChilled and

Light-Sensitive

Legal Specimens

Chapter 5 6


Blood Cultures• Requested on patients

with a high fever

• Purpose is to isolate microorganisms from the patient’s blood that may be causing the fever

• Strict aseptic technique is required for the collection of the blood specimen

Blood culture bottles are larger than normal venipuncture tubes

Chapter 5 7


Blood Cultures Part 2• Blood culture bottles

contain culture media, which enhances the growth of the microorganisms

• Septicemia is the presence of microorganisms in the blood with symptoms that can result in death

• Blood cultures are usually ordered STAT

• Collected in sets of two or three

• Each set is collected from different sites at different time intervals

One sample will be incubated as an One sample will be incubated as an anaerobicanaerobic specimen and the other as an specimen and the other as an aerobicaerobic specimen specimen

Chapter 5 8


Blood Cultures Part 3• Blood cultures seek to

identify the agent(s) responsible for the patient’s illness

Common Pathogen ClassificationsCommon Pathogen Classifications

•Bacteria

•Fungi

•Protozoa

•Viruses

Chapter 5 9


Blood Culture VolumeBlood Culture Volume

•The exact amount indicated by the manufacturer must be collected.

•Usually 8 to 10 mL per bottle or tube is sufficient for an adult. Lesser amounts are drawn on infants and children.

•The correct amount is needed to increase the chance of bacterial growth.

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Blood Cultures Part 4The collection of blood cultures is essentially the same as for routine venipuncture, except:

• Amount of blood needed

• Special site cleansing

• Specimen transfer

Chapter 5 11


Site Cleaning ProcedureBlood Culture Site Cleaning Procedure

Steps to Correct Cleaning

1. Release the tourniquet after site is selected

2. Clean first with 70% to 95% alcohol, chlorhexidine gluconate, or benzalkonium chloride using concentric circles, from the center working outward

3. Do not allow the strokes to go back toward the center area

Correct cleaning of the site is the most important part of collecting blood cultures

Chapter 5 12


Site Cleaning Procedure Cont’dSteps to Correct Cleaning (cont’d)

4. Allow the site to air dry

5. Repeat cleansing using a 2% iodine swab or applicator if using alcohol

6. Allow iodine to dry and do not retouch the area

If the patient is allergic to iodine, use another cleanser.

Chapter 5 13


Blood Culture Specimen Transfer

Collecting Blood Culture Specimens

• If using a syringe, be sure to have a syringe that can hold at least 20 mL. Attach the syringe to a transfer device and fill anaerobic bottles first.

If a butterfly setup is used, the aerobic sample is drawn first so that air from the butterfly tubing is cleared before the anaerobic culture sample is drawn.

Chapter 5 14


These specimens must be correctly identified and under the uninterrupted control of authorized personnel to ensure their validity.

• Establishing a chain of custody is required for medicolegal issues. Without proper proof of custody, the specimen will be considered invalid.

• A chain of custody form must be completed correctly, and multiple copies are used as a safeguard system.

Chapter 5 15


Cold Agglutinins•Testing for cold agglutinins or

antibodies is done for patients suspected of having atypical pneumonia.

•Atypical pneumonia is caused by the microorganism Mycoplasma pneumoniae.

•People infected with Mycoplasma pneumoniae produce autoantibodies.

Chapter 5 16


Cold Agglutinins Part 2Normal body temperatures range from 97.6F to 99.6F. At temperatures lower than normal body temperature, cold agglutinins attach to red blood cells and cause clumping.

Specimen Collection

• Use red-topped tubes that do not contain additives

• Collection tubes must be prewarmed

• Keep the sample at 98.6F until the serum can be separated from the cells

• Serum must be separated from cells within 1 hour

Chapter 5 17


• Some specimens must be chilled or covered immediately after collecting.

Chilled Specimens

•Arterial blood gases

•Ammonia

•Lactic acid

Light-Sensitive Specimens

•Bilirubin

Chapter 5 18


Apply Your Knowledge Part 2Which of the following best describes the correct cleansing procedure for blood culture collection?

A. Clean the arm starting a distance from the site and clean toward the selected site

B. Use linear strokes to clean up and down the arm until the entire arm is cleansed

C. Clean the site starting in the center and working outward

Answer: C. Clean the site starting in the center and working outward GREAT!

Chapter 5 19


Apply Your Knowledge Part 3

James is suspected of having atypical pneumonia. Which of the following tests will most likely be ordered?

A. Arterial blood gases

B. Cold agglutinin

C. Bilirubin

Answer: B. Cold agglutinin tests for atypical pneumonia caused by Mycoplasma pneumoniae

BRAVO!

Chapter 5 20


Unopette ProcedureA Unopette®, manufactured by Becton-Dickinson, is a prepackaged microcollection device.•Disposable•Consists of a plastic reservoir

containing a premeasured volume of reagent

Common Tests Performed with a Unopette

•White blood cell count•Red blood cell count•RBC fragility

•Platelet count•Hemoglobin

Chapter 5 21


Unopette Procedure Part 2Each test requires a specific Unopette that has a different premeasured volume of reagent inside.• Specific pipettes accompany each Unopette.• Pipettes are self-filling, thin-walled, glass

capillary tubes attached to a plastic holder.• Use a dermal puncture specimen to fill the

pipette.• Wipe the pipette after it fills with blood, but

do not touch the end of the pipette with gauze.

• Gently invert to mix the sample with the reagent.

• Label Unopette and transport to lab.

Chapter 5 22


Apply Your Knowledge

Which tests can be performed with the Unopette microcollection device?

ANSWER: WBC count, RBC count, RBC fragility, platelet count and hemoglobin

Good Job!

Chapter 5 23


Measuring Microhematocrit• Microhematocrit tubes are

used for measuring hematocrit or packed cell volume

• They have a thin red band around the end of the tube

• These tubes are coated with sodium heparin

• Blood flows freely into these tubes because of capillary action

Chapter 5 24


Measuring Microhematocrit Part 2• Fill two capillary tubes 3/4

full• Seal the end that was not

used to collect the specimen by embedding the clean end into a clay sealant (if the tube requires it)

• Place in a separate tube for labeling and transporting to the laboratory

• Place in centrifuge machine according to procedureNOTE: The values of the two microhematocrits should match within 2 percent.

Chapter 5 25



True or False: Microhematocrit tubes are coated with an anticoagulant.

Hey, remember! An anticoagulant prevents

blood from clotting.

Answer: TrueGreat!

Chapter 5 26


Peripheral Blood SmearA blood smear is for the microscopic examination of blood.

• Venous or capillary blood may be used to prepare a blood smear.

• The complete blood count (CBC) differential test is done with a blood smear.

• Blood smears are also used to diagnose malaria, anemia, and leukemia.

Chapter 5 27


Peripheral Blood Smear Part 2Blood Smear Procedure

• Fresh drops of blood are obtained, usually following dermal puncture

• Wipe away the first drop of blood

• Place 1 drop of blood about 1/2 inch from the frosted end of one glass slide

• Hold the spreader slide at a 30 to 35o angle and spread blood toward the opposite end of the slide

• The blood smear should be smooth in appearance with no irregularities, streaks, or holes and a feathered edge

• The wedge method is the most common technique for making blood smears

Chapter 5 28



Blood smears are used to diagnose which of the following diseases?

A. MalariaB. LeukemiaC. AnemiaD. All of the aboveE. None of the above

ANSWER: D. All of the above

Bravo!

Chapter 5 29


Point-of-Care Testing• Near-patient testing• Designed to reduce hospital cost and reduce

turnaround time for blood test results• Instruments are portable, internally calibrated,

and easy to use• Point-of-Care testing (POCT) is usually

performed by phlebotomists, nurses, technicians, or medical assistants

• Dermal puncture usually done because a small blood specimen is needed

• Each instrument must be calibrated and requires quality control checks

Chapter 5 30


Point-of-Care Testing Part 2

• Glucose

• Hemoglobin

• Sodium

• Potassium

• Bicarbonate

• Ionized calcium

• Cholesterol

• Blood ketones

• Urine dipstick

• PT and PTT

• Chloride

• Blood gases

Common Point-of-Care Tests

Chapter 5 31


• Often requires blood from a dermal puncture.

• POCT is done at various facilities.

• If a clinical lab is not available, only CLIA waived testing can be performed.

• CLIA waived tests are those that are cleared for home use.

Chapter 5 32


Before the Test• Confirm test orders

• Establish a procedure for patient ID

• Give patient pre-test instructions

• Collect specimens according to package directions

• Label specimens appropriately

• Never use expired kits

Chapter 5 33


During the Test• Perform quality control testing

• Correct any problems

• Establish a policy for frequency of control testing

• Carefully follow all test-timing recommendations

• Interpret test results using product inserts as a guide

• Record test results according to office policy

Chapter 5 34


After the Test

• Report results in a timely manner

• Follow package insert for follow-up

• Follow OSHA regulations for disposing of biohazardous waste

• Participate in quality assurance assessment programs

Chapter 5 35



Which of the following tests cannot be performed with POCT?

A. Glucose

B. Hemoglobin

C. Blood culture

D. Cholesterol

Answer: C. Blood cultures require a larger amount of blood and have to grow in culture media.

Good Job!

Chapter 5 36


• Used to evaluated substances found in urine

• Consist of the physical component, chemical component, and the microscopic component

• First morning urine is best used for testing

• Chain of custody must be established for drug and alcohol testing

• Should be refrigerated if not tested within 1 hour

Chapter 5 37


Obtaining Urine Specimens

• For a Female:• Separate the skin folds and wipe front to

back three times• Keep the skin folds apart and collect a

midstream urine in the cup• Once ¾ full, place the lid on the cup• Label the specimen

• For a Male:• Use 2 towelettes to clean the head of the penis• If uncircumcised, keep foreskin retracted while patient urinates

and collect a midstream urine in the cup• Once ¾ full, place the lid on the cup• Label the specimen

Chapter 5 38


Urine Specimen Testing

The Urine Dipstick

• Uses reagent strips to test urine for a number of substances

• Keep strips in a cool dry area

• Never remove them from the container until ready to test

• Examine the strips for discoloration

• Check the expiration date

• Always run a control sample when opening a new supply

• Write the date opened

Follow the manufacturer’s directions for accurate results

Chapter 5 39



Which is the best urine specimen for testing?

ANSWER: The first morning urine

GREAT!

Chapter 5 40


Centrifuge OperationCentrifuging is the spinning down or separating of cells from the liquid portion of the blood.

• Specimens also require aliquoting (dividing specimens into separate containers)

• Aliquoting for most laboratory tests requiring serum or plasma must be done within two hours or less

What happens if the specimen is not separated in time?

• Test results could be altered

• If the RBCs are left in contact with the serum, the glucose level would be decreased

Chapter 5 41


Centrifuge Operation Part 2Types of Centrifuges

• Refrigerated• Floor models• Tabletop models

The speed of rotation and the radius of the rotor head determine the relative centrifugal force of a centrifuge, which is expressed in gravity (g).

Most laboratory specimens are centrifuged at 750 to 1000 g for 15 minutes

Chapter 5 42


Centrifuge Operation Part 3•Place tubes of

equal size and volume directly across from each other so the machine will be balanced

•Never open the lid until the centrifuge machine has come to a complete stop

After centrifugation, always be sure the transfer tube is properly labeled before you begin to aliquot a specimen

Chapter 5 43



Within what time frame should specimens be centrifuged for tests that require serum or plasma?

ANSWER: Within 2 hoursGREAT!

Chapter 5 44


CHAPTER SUMMARY

• Specimens may require special handling or collection in order to be accurate.

• Blood cultures must be drawn under strict aseptic technique to prevent false results.

• When using a Unopette, collect the specimen with the pipette and mix the specimen carefully.

• To perform a microhematocrit, obtain blood in a capillary tube and centrifuge. The separated cells can be used to determine the patient’s hematocrit.

Chapter 5 45


CHAPTER SUMMARY (cont’d)

• Peripheral blood smears require a drop of blood on a slide. The blood is spread across the slide using a spreader slide.

• Point-of-care tests are obtained and tested immediately at the point of care or near the patient. CLIA waived tests pose a minimal risk to the patient.

• A urine specimen can be collected and a reagent strip may be used to determine the concentration of a substance.

• When using a centrifuge, make sure the load is balanced.

Chapter 5 46


END OF CHAPTER 5

Choose a job you love and you will never have to work a day in your life.

-- Confucius

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display Chapter 51 Booth, Wallace, and Fitzgerald PowerPoint Presentation.

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