Chapter 9 phleb PDF

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CHAPTER 9Special Processing and HandlingIn addition to blood collection, some specimens require special handling either or after the blood is collected.Common test requiring special handling Procedures Blood cultures  Legal specimens  Cold agglutinins  Chilled and light-sensitiveBLOOD CULTURES ...

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CHAPTER 9

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Special Processing and Handling

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In addition to blood collection, some specimens require special handling either or after the blood is collected.

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Common test requiring special handling Procedures    

Blood cultures Legal specimens Cold agglutinins Chilled and light-sensitive

BLOOD CULTURES   

Requested on patients with 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     

Blood culture bottles contain culture media, which enhances the growth of the microorganisms Septicemia is the presence of microorganism 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 anaerobic specimen and the other as an aerobic specimen 

Blood cultures seek to identify the agents responsible for the patient’s illness

Common Pathogen Classifications    

Bacteria Fungi Protozoa Viruses

Blood 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

The collection of blood culture is essentially same as for routine venipuncture except:   

Amount of blood needed Special site cleansing Specimen transfer

Blood culture site cleaning Procedure Correct cleaning of the sites is the most important part of collecting blood cultures 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 stokes to go back toward the center area 4. Allow the site 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 patient is allergic to iodine, use another cleanser 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 butterfly setup is used, the anaerobic sample is drawn first so that air from the butterfly tubing is cleared before the anaerobic culture sample is drawn LEGAL SPECIMEN 

Establishing a chain of custody is required for medicolegal issues.

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Without 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.

These specimen must be correctly identified and under the uninterrupted control of authorized personnel to ensure their validity. COLD AGGLUTININS 

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Testing for cold agglutinins or antibodies is done for patients suspected of having atypical pneumonia Atypically pneumonia is cause by the microorganism Mycoplasma pneumonia People infected with mycoplasma pneumonia produce autoantibodies

Normal body temperatures range from 97.6°F to 99.6° F. At temperatures lower than normal body temperature, cold agglutinins attach to red blood cells and cause clumping. Special collection    

Use red-topped tubes that do not contain additives Collection tubes must be prewarmed Keep the sample at 98.6°F until serum can be separate from the cells Serum must be separated from cells within 1 hour

Arterial blood gas 

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Ammonia Plasma (K2EDTA)= specimen volume required is 1mL aliquot plasma (0.5mL min)     

Chilled Specimen   

Arterial blood gases Ammonia Lactic acid

Light-sensitive Specimens 

Bilirubin

Mix well and place specimen in ice slurry If there is delay in testing the sample should be refrigerated or frozen Exposure to air should be minimized Hemolyzed specimen are rejected Avoid the use tourniquet and clenching of fist

Lactic Acid      

Whole blood anticoagulant with heparin 1mL whole blood (0.4mL min) Should be placed immediately in ice slurry if delayed testing (1hr) Should be analyzed within 30 mins Hemolyzed specimen is rejected Avoid the use tourniquet and clenching of fist

Bilirubin   

CHILLED AND LIGHT-SENSITIVE SPECIMENS Some specimen must be chilled or covered immediately after collecting.

CLSI-should be analyzed within 30 minutes when collected in plastic syringes and stored at room temperature If longer storage time is required, it is recommended to use glass syringes with adequate specimen cooling Cooling (dipped in iced water)

Serum (red top or sst) 2mL (0.2mL minimum) Specimen should be protected from bright light

Unopetted Procedure A unopette, manufactured by BectonDickson, is a prepackaged microcollection device  

Disposable Consist of plastic reservoir containing a premeasured volume of reagent

Common tests performed with Unopette  

WBC count RBC count

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RBC fragility Platelet count Hemoglobin

Each test requires a specific Unopette that has a different volume of reagent inside.      

Specific pipettes accompany each Unopette Pipettes are self-filling, thin-walled, glass capillary tube attached to a plastic holder Use adermal 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

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Procedurea     

Hemocytometer- count number of cell Measuring microhematocrit    

The complete blood count (CBC), differential test is done with a blood smear Blood smears are also used to diagnose malaria, anemia, and leukemia

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Microhematocrit tubes are used for measuring hematocrit or packed cell volume They have thin red band around the end of the tube These tube are coated with sodium heparin Blood flows freely into these tubes because of capillary action

Fresh drops of blood are obtained, usually following dermal puncture Wipe away the first drop of blood Place 1 drop of blood about ½ inch from the frosted end of one glass slide Hold the spreader slide at 30° to 35° 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

Procedure  

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Fill two capillary tubes ¾ full Seal the end that has 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 procedure

Note: The values of the two microhematocrits should match within 2%.

Point of care testing    

PERIPHERAL BLOOD SMEAR A blood smear is for the microscopic examination of blood. 

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

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Near-patient testing Designed to reduce hospital cost and reduce tunaround time for blood test results Instruments are portable , internally calibrated, and easy to use Point-of –care testing (POCT) is usually performed by phlebotomists, nurse, 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

Common Point of Care Tests            

Glucose Hemoglobin Sodium Potassium Bicarbonate Ionized calcium Cholesterol Blood ketones Urine dipstick PT and aPTT Chloride Blood gas

Centrifuge Operation Centrifuging is the spinning down or separating of cells from the liquid portion of the blood.  

Specimen also require aliquoting (dividing specimens into separate containers) Aliquotung for most laboratory tests requiring serum or plasma must be done within two hrs or less

If the specimen is not separated in time:  

Test results could be altered If the RBCs are left in contact with serum, the glucose level would decreased

Type of Centrifuges   

Refrigerated Floor models Tabletop models

The speed of rotation and the radius of the rotor head determine the relative centrifuge force of a centrifuge, which is expressed in gravity (g). Most laboratory specimens are centrifuge at 750 to 1000 g for 15 mins. Procedure  

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 10 Processing and handling non blood specimen URINE SPECIMENS     

Used to evaluate substance 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 hr

Obtaining urine specimens For a Female:    

Separate the skin folds and wipe front to back three times Keep the skin fold apart and collect a midstream urine in a cup Once 2/4 full, placethe 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 patients urinates and collect a midstream urine in the cup Once ¾ full, place the lid on the cup Label the specimen

Urine specimen      

First morning urine Random Timed specimen – 24hr or 12 hr Catheterized specimen Clean catch midstream Suprapubic aspiration

Preservation Refrigeration at 5°C – for routine urinalysis

Chemical Preservation

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Boric acid, hydrochloric acid, acetic acid, and oxalic acid

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Urine specimen testing The Urine Dipstick       

Uses reagent strips to test urine for a number of substance Deep strips in a cool fry 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 direction for accurate results Urine culture    

Midstream urine collection Sample container must be sterile for culture to accurate Sample should be less than an hour old If there is delay in testing (>1hr) the sample must be refrigerated

Obtaining Semen Specimens     

Determine the number and activity of sperm contained in the semn Part of fertility study Post vasectomy sample- to determine if vasectomy was successful Sample should be tested within 30 mins – sperm cells rapidly deteriorate and loses sperm mobility # of sperm cell, sperm mobility, abnormalities

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Throat sample Good:  Back of the throat  Tonsils Unsuitable:  Sides of the mouth  Tongue Sputum sample    

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Avoid consumption of alcohol Avoid ejaculation at least 3 days Condoms and lubricants should not be used The entire specimen must be collected

Culture Specimen Throat sample

Mucus and phlegm that a person will cough out from the lungs, bronchi, or trachea “Deep cough” and expectorated in a sterile container Before collection, patient should rinse his mouth with water to remove excess food and bacteria Sample is maintained at room temp.

Nasopharyngeal culture    

Patient Instruction   

Throat culture/sputum sample for culture Patient experience sore throat “throat swab” – throat should be swabbed with enough force to remove organisms adhering to throat membrane Swab area with redness, rawness, or white patches for optimum streptococcal isolation

Culture of the nasal cavity and pharynx Dacron or cotton-tipped flexible wire swab Swab shaft is made to bend so that it ca be pushed into the nose and then pass into the nasopharynx As the swab is removed it is rotated to collect the sample

Stool culture     

Help evaluate gastrointestinal disorders Test for occult blood (hidden) Collection is often embarrassing to patients How to collect? Large collection bowl on the toilet bowl

Meconium or umbilical cord tissue      

Mother using drugs will cause the neonate to be dependent on the same drugs Early detection – testing for presence of drugs in meconium or umbilical cord tissue Meconium is preferred over urine Urine will test only the last 1 to 10 days Drug detection use over an extended period of time, covering at least the last trimester of pregnancy Meconium may take several days to be expelled and the umbilical cord is available upon delivery...