{mosimage}by Dr. Ramaz Mitaishvili
Pre-analytical source of errors
Pre – analytical – involves all issues from test request to processing sample
Patient Identification and labeling
- "zero tolerance" for patient misidentification (positive patient identification is the No. 1 step in the entire phlebotomy practice)
- identification bracelet and room number
- when the patient is comatose or cannot communicate
NOTE: If any preanalytical errors occur, specimen can not be processed.
Specimen Identification Errors
Nothing is more basic to safe and effective patient care than ensuring that the caregiver is performing the right procedure on the intended patient. Misidentification of patients, laboratory specimens, surgical sites, and medications is a fundamental defect throughout the healthcare system, causing many preventable adverse events. The effects of misidentification can be catastrophic.
July 2004 – Officials at a Florida hospital acknowledge that a woman was infused with the wrong type of blood in June. The woman died about a day after receiving the erroneous transfusion, which happened because a blood sample was mislabeled.
July 2003 – A woman who switched beds to be closer to the window died after she was given the wrong type of blood during surgery at a Virginia hospital. A technician had taken a blood sample from her roommate.
The medical personnel will identify an inpatient by asking them to state and spell their full name and state their birth date (year, month and day)
The medical personnel will identify an inpatient for blood collection by use of the hospital identification bracelet on his/her person.
In situations where it is not feasible for a patient to have an identification bracelet on their person, for example burn patients, the medical personnel will obtain the identification of the patient from the attending nurse or physician prior to blood collection. The identifying personnel will sign a form indicating that they identified the patient.
Determination of name and DOB (Be sure to properly identify the patient.
a) Does the name patient spelled match requisition?
b) Does the name on the patient’s chart match the name on the patient’s identification?
c) If more than one patient is present with the same first and last name, how do you determine which one is the test patient? (Look for possible gender differences, social security number, patient identification number, birthdates, different middle name, and relevance of the test to the patient’s history).
Checking ID bracelet (Additional information helping in proper identification (room number, bed number, physician’s name, Medical Record number, examples when same last and first name, moved bed, different physicians and etc.)
ID discrepancies (double check, nurse notification, identity verification)
Missing ID bands and requisition
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The medical personnel will identify an outpatient by asking them to state and spell their full name and state their birth date (year, month and day), as well as by obtaining the patient’s provincial health card or hospital card upon each visit.
Pediatric patients may be identified by their parent/guardian.
If a patient does not have a provincial health card or hospital card, the medical personnel will obtain another form of I.D. such as a driver’s license or credit card. The patient may be required to contact Data Maintenance with their personal health number.
Determination of name and DOB (Be sure to properly identify the patient asking patient to spell name.
a) Does the name spelled by the patient match requisition?
b) Does the name on the patient’s chart match the name on the patient’s identification?
c) If more than one patient is present with the same first and last name, how do you determine which one is the test patient? (Look for possible gender differences, social security number, patient identification number, birthdates, different middle name, and relevance of the test to the patient’s history).
Labeling Process
All collection tubes and request forms must be labeled clearly with the patient's ID sticker. When this is not available, their NHI number or temporary hospital number, surname and date of birth must be written on the tube(s). The request form must state clearly which tests are required and include the same patient information as the sample collection tubes. The request form should also include the date and time of sample collection as well as a clear indication of the requesting doctor and location of the patient.
Specimen Labels and Blood Collection Lists
1. Specimen identification is essential.
a. Must be clear an accurate.
b. Begins immediately upon collection and continues through disposal.
c. Methods for labeling will vary.
2. Computer versus manual labeling.
a. Most sophisticated, accurate and efficient method is computer labels.
b. Orders put in at any time for a morning run, collection lists are generated prior to
morning run.
c. Labels generated by the computer are put on specimens, phlebotomist adds date,
time and initials.
d. Extra labels are used in lab for labeling tubes, cuvettes, and slides.
e. Barcodes add to organization and accuracy of specimen testing.
f. Manual methods are time consuming and prone to transcription errors.
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Information
(dietary, previous complications and etc.)
Phlebotomy best practices can't work in a vacuum. The clinical laboratory has to act as a safety net by performing a number of visual, mechanical, and computerized safety checks to ferret out detectable problem specimens. Listing the potential problem on the test requisition, such as a difficult draw, which could produce some level of hemolysis. Or they might note that the patient may have been under stress or not feeling well, which will affect glucose levels. The phlebotomist have to turn the lab test requisition inside out to further alert the person processing the specimen to pay special attention to it. Phlebotomist has to avoid blood draw if he or she are under stress or not feeling well (for example, after double shift, too many orders for venipuncture and etc.)
Using of correct tubes
Blood Collection/Transport Containers
The accuracy of any result depends upon the quality of the specimen. Following the collection, preparation, and transport instructions suggested helps to ensure the best possible test results.
Proper identification of specimens is extremely important. Clearly label each specimen with the patient's first and last name as they appears on the test request form. Additional desirable information on the specimen includes date and time of collection, account number, and specimen type (eg, serum or plasma). A unique identifier may be substituted for the patient's name. Information on preprinted labels must be verified before the specimen is submitted to the laboratory. The name on the test request form must exactly match the patient's name on the specimen submitted. Tubes may be labeled individually or placed into a properly labeled larger, clean tube (secondary container) and submitted to the laboratory.
Anticoagulants and Preservatives. To ensure accurate test results, all tubes containing an anticoagulant or preservative must be allowed to fill completely. Attempts to force more blood into the tube by exerting pressure, as in collection with a syringe, will result in damage to the red cells (hemolysis). If the vacuum tube is not filling properly, and you are certain that you have entered the vein properly, substitute another tube. Occasionally, vacuum tubes lose their vacuum. If the specimen cannot be properly collected, select another site and using new, sterile collection equipment, collect the specimen.
Note: Use plastic transport tubes for all frozen specimens.
Specimen Containers
Red-stopper tube: Contains no anticoagulant or preservative.
Use: Serum or clotted whole blood. Serum must be separated from cells within 45-60 minutes of venipuncture. Send serum in a plastic transport tube.
Mottled red/gray or cherry red-stopper (serum-separator) tube: Contains clot activator and gel for separating serum from cells, but not anticoagulant. Do not use serum-separator tubes to submit specimens for therapeutic drug monitoring. Always check the test description to determine whether a serum-separator tube is acceptable.
Use: Serum. May be used for assays requiring serum unless otherwise stated. Separate serum from cells within 45 minutes of venipuncture. Serum may be sent in the centrifuge tube with an intact barrier (correct separation upon centrifugation) between cells and serum or in a plastic transport tube. If specimen is centrifuged before clotting is complete, a fibrin clot will form on top of the cell. This finding is frequent in hemolyzed specimens.
Lavender-stopper tube: Contains liquid K3 EDTA.
Use: EDTA whole blood or plasma. Send plasma in a plastic transport tube labeled "Plasma, EDTA." Send whole blood in a lavender-stopper tube.
Gray-stopper tube: Contains sodium fluoride (a preservative) and potassium oxalate (an anticoagulant).
Use: Sodium fluoride whole blood or plasma. Send plasma in a plastic transport tube labeled "Plasma, Sodium Fluoride." Send whole blood in a gray-stopper tube.
Blue-stopper tube: Contains sodium citrate. Be sure to use only tubes with a 3.2% sodium citrate concentration. These are easily identified by the yellow diagonal stripes on the label.
Use: Sodium citrate plasma. Send plasma in a plastic transport tube labeled "Plasma, Sodium Citrate." Send whole blood in a blue-stopper tube.
Green-stopper tube: Contains sodium heparin or lithium heparin.
Use: Heparinized whole blood or plasma. Send plasma in a plastic transport tube labeled "Plasma, Sodium Heparin" or "Plasma, Lithium Heparin." Send whole blood in a green-stopper tube.
Yellow-stopper tube: Contains 1 mL acid citrate dextrose (ACD) solution.
Use: ACD whole blood. Send whole blood in a yellow-stopper tube.
Royal blue-stopper tube: Contains sodium EDTA for trace metal studies.
Use: EDTA whole blood or plasma. Send whole blood in a royal blue-stopper tube. Send plasma in a plastic transport tube labeled "Plasma, EDTA"
Plastic tubes. Although plastic red-stopper and serum-separator tubes are becoming the standard for assays performed on serum, they are not preferred in all situations. Plastic tubes are not appropriate for blood drug screens or serum or blood alcohol tests. The use of plastic tubes may yield inaccurate results; consequently, the preferred container for these assays is glass. Specimens for the following procedures should not be submitted in plastic tubes.
- Cannabinoids (Marijuana), Blood (767665)
- Drug Coma/Overdose Profile II, Blood and Urine or Gastric Contents
- Drug Coma/Overdose Profile II, Blood and Urine (With Cannabinoids)
- Drug Profile, Blood (5 Drugs)
- Drug Profile, Blood (7 Drugs)
- Ethanol, Blood
- Methanol, Blood
- Volatiles, Blood
- Zinc, Plasma/Serum
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Hemolysis, Lipemic Serum or Plasma (Turbidity), and other interference with results
Basal state = early in the morning after a 12 hour fast. This basal state allows for comparison of a patient’s test results with normal values or reference ranges for patients in the same age group. However, all of the following patient physiologic variable can affect test results in various ways:
- age
- altitude from sea level
- diet
- diurnal variation, especially if unusual sleep pattern
- drug therapy
- exercise
- fever
- gender
- jaundice
- position
- pregnancy
- smoking
- stress
- temperature and humidity
(falsely increase results for potassium, magnesium, iron, lactate dehydrogenase, phosphorus, ammonia, and TP)
Improper phlebotomy techniques (Using small needle, pulling a syringe plunger back too fast, expelling the blood vigorously into a tube, shaking tubes vigorously, improper storage temperature)
Normal serum or plasma is a clear and light yellow to straw in color. Turbid serum or plasma appears cloudy or milky. Serum or plasma may be cloudy due to bacterial contamination or chronic or transient high lipid levels in the patient's blood. The primary dietary sources of lipids (fatty substances) are meats, butter, cream, and cheese. Patients who consume these foods within the 24-hour period immediately preceding collection of a blood specimen may have temporarily elevated lipid levels, which may be manifested by cloudy or lipemic serum. Lipemic serum or plasma may not be a true indicator of the patient's physiologic state. Regardless of diet and length of fast, some patients may produce cloudy specimens. To avoid dietary-induced high lipid levels prior to testing, many physicians require patients to exclude the high-fat foods from their diets or to fast for 12-14 hours prior to specimen collection. For morning specimen collection, the laboratory recommends that the patient be required to fast from 6 PM on the previous evening.
a. Chilled samples -blood gases, gastrin, ammonia, lactic acid, renin, catecholamine,
parathyroid hormone, ACTH and glucagon.
b. Protect from light – bilirubin, vitamin B12, carotene, folate and urine samples for
porphyrin determination.
1) Bilirubin is a byproduct of red cell breakdown, if excessive amounts
accumulate in babies can cause brain damage.
2) It is light sensitive, and falsely decreased results may be obtained when
improperly transported.
3) Protect from light by wrapping in foil or placing in a box.
c. Warmed samples -cold agglutinins and cryoglobulin.
d. Microbiology samples should be delivered to the department immediately to enhance
ability to grow pathogenic organisms.
e. Positioning vacuum tubes after collection.
1) Maintain microtainers and vacuum tubes in an upright, vertical position.
2) This is done to for two purposes: Promote clot formation, if required and
reduce possibility of hemolysis.
* Specimen timing or storage problems, whether the specimen is any good if it was left out all night at room temperature unspun or even spun.═ What kind of errors would we expect it this happened to a specimen? chemical activity and degeneration of the cells within the tube will take place, and test results may be altered. Low glucose level, High potassium and LDH levels.
If, for example, fasting blood glucose test is needed many things can affect the test results.
Consuming food or drink less than 12 hours before testing will affect fasting blood glucose test results. If the meal eaten just before the 2-hour postprandial test is not high in carbohydrates, the test may not be accurate. Medications that can raise blood glucose levels include birth control pills, phenytoin (Dilantin), furosemide (Lasix), triamterene (Dyrenium, Dyazide), hydrochlorothiazide (Esidrix, Hydro Par, Oretic), niacin, and corticosteroids (prednisone or hexadrol). Medications that can lower blood glucose levels include clofibrate (Atromid), high blood pressure medications such as propranolol (Inderal), and some medications used to treat depression. Drinking alcohol may also lower blood glucose levels. Illness or emotional stress, smoking, and caffeine can raise blood sugar levels. Rough handling, contamination, or inadequate refrigeration of the blood sample can cause inaccurate test results.
