Samples Information and Courses from MediaLab, Inc.

The cerebrospinal fluid sample should be properly labeled with the tube number, patient's name and hospital number. The samples should be transported to the laboratory immediately.

The stability of the CSF sample varies depending on the procedures ordered. Cell counts are ALWAYS STAT and should be performed within 30 - 60 minutes for best results. Samples should be left at room temperature for no longer than one hour and refrigerated following testing. Refrigeration is not recommended for culture specimens since fastidious organisms such as Haemophilus influenzae and Neisseria meningitidis may not survive the cold temperature.

Spinal fluid samples are either clear or turbid. Some sources use the following rating system for turbid CSF specimens: 0 = crystal clear fluid 1+ = faintly cloudy, smoky, or hazy 2+ = turbidity clearly visible but newsprint read easily through tube 3+ = newsprint not easily read through tube 4+ = newsprint cannot be seen through the tubeTurbidity may be caused by leukocytes, erythrocytes, fungi, bacteria, amoebae, contrast media, or aspiration of epidural fat during puncture.200 leukocytes/mm3 will cause slight turbidity (1+); increased numbers of WBCs will cause increased turbidity. At least 400 erythrocytes/mm3 are needed to produce 1+ turbidity.Occasionally CSF will have an oily appearance due to the presence of substances remaining in the CSF after radiologic (x-ray) procedures have been performed.

Tissue cells that are never seen in peripheral blood but are often seen in spinal fluid samples are presented in the table below: Cells Causes macrophages RBC's in CSF viral meningitis tubercular meningitis ependymal normal - due to shedding of cells that line the ventricles pia arachnoid mesothelial cells (PAM) normal - due to shedding of cells lining the arachnoid space These cells are important because they must be differentiated from tumor cells and blast cells.

Although the procedure is simple to perform, accurate results depend on careful adherence to manufacturer’s directions and adequate quality control. Normal and abnormal controls should be tested whenever a new lot of strips is opened, and at the frequency defined by the laboratory's procedure. If quality control results do not correspond to the published control values, the problem must be resolved before patient samples are tested. High levels of ascorbic acid (Vitamin C) in the urine may inhibit some reagent strip reactions, such as glucose, blood, bilirubin, nitrate and leukocyte esterase. The urine dipstick's package insert will provide information about potential interfering substances, including ascorbic acid. Intensely colored urine may make it difficult to correctly interpret color reactions on the dipstick. The affected tests should not be reported from the dipstick. It would be necessary to use an alternative method of testing if available.

No blood is found in the urine of healthy individuals although samples from menstruating females, frequently, but not always, test positive for blood. Hematuria is associated with renal or genital urinary disorders in which the bleeding is the result of irritation to the involved organs or trauma. Examples include renal calculi, pyelonephritis, glomerulonephritis, tumors, trauma or exposure to toxic chemicals or drugs and/or strenuous exercise. Hemoglobinuria may be due to the lysis of red cells within the urinary tract. If it is caused by intravascular hemolysis, the hemoglobin is then filtered through the glomeruli. In the normal individual, the hemoglobin molecule attaches to haptoglobin and in this way bypasses the kidney filtration system. When the hemoglobin/haptoglobin system is overwhelmed, as in cases of hemolytic anemia, severe burns, transfusion reaction, infection or strenuous exercise, hemoglobin passes into the urine.

In statistics, a variable is any quantity that is a part of a data point. Variables can either be dependent or independent. An independent variable is a quantity that is directly controlled by the observer or experimenter. The dependent variable, as its name suggests, depends on the independent variable. The dependent variable is often the quantity you want to measure, and it the result of the experiment or test.For example, you may want to determine the relationship between hemoglobin concentration and age. You select people of various ages, and then test their hemoglobin concentrations. Age is the independent variable, and is controlled by the experimenter (you can select which ages are in the experiment). The dependent variable is the resulting hemoglobin concentration.In some cases, these criteria may not be useful in determining which variable should be the independent variable, such as determining the correlation between the readings given by two different instruments for the same samples. In that case, there might be other criteria for selecting the independent variable.

You also have the choice of plotting the relative or the absolute frequency along the y-axis. The relative frequency is better for large samples. The shape of the graphs, however, is the same for both methods. Figure 6 Absolute Frequency of Serum Glucose Levels in 130 Hospital Employees Figure 7 Relative Frequency of Serum Glucose Levels in 130 Hospital Employees

In addition to the responsibilities listed for Level 3, over 40 laboratories also participate in Level 2 activities. At this level, laboratory personnel are trained to detect exposure to a limited number of toxic chemical agents in human blood or urine, the analysis of cyanide and toxic metals in human samples, for example.

The sites used to obtain bone marrow samples are:illiac crest (posterior, anterior)sternumspinal processestibia - (infants and newborns)The illiac crest is the most common site for bone marrow collection. Sternal aspiration can have serious or even fatal consequences if the needle penetrates the heart.

Lymphocytes are often located in nodules and these nodules are unevenly distributed throughout the marrow so the lymphocyte count may vary in bone marrow samples from different sites. Plasma cells are often found clustered around blood vessels. Monocytes seem to congregate about arterioles in the center of the cord.

Control materials are made to match patient samples in physical and chemical characteristics. Control samples are often made with biological material.Control samples are tested in the same way as patient samples. If the results from testing a control sample are not within the acceptable ranges, we assume there has been a problem in the test procedure, equipment, or the samples themselves. There are many criteria for rejecting a test based on the control samples measurements; these criteria will be detailed further in a later section.Patient results are not reported until the cause of the problem has been found, the problem resolved, and the controls re-run to verify that everything is working normally.

External quality control is performed to ensure the reliability of test results between different laboratories. It is also required by CLIA for laboratory accreditation. External quality control is generally accomplished through proficiency testing (PT). In proficiency testing, simulated patient samples are sent out to laboratories for testing. The CLIA standards for handling proficiency testing specimens are as follows: PT samples must be tested with the laboratory's regular patient load. PT samples must be tested the same number of times that patients' samples are tested routinely. Laboratories participating in PT programs must not engage in interlaboratory comparison of PT sample results. Laboratories may not send PT samples to another laboratory for analysis. Laboratories must document all steps of processing for PT samples. PT is required for only the primary method used for testing of analytes in patients' samples during the period covered by the PT event.In return for their participation, the laboratory will receive the following information: results for each analyte sample mean result for each analyte standard deviation of results by the comparative method number of laboratories using the same method standard deviation index (SDI) lower and upper limits of acceptability of resultsPT results that are between the lower and upper limits of acceptability are considered satisfactory. For chemistry, 80% of samples must test within the acceptable range for the PT to be considered successful. External quality control serves several purposes, including: providing a check on internal quality control detecting errors in a lab's methods providing a comparison of testing methods, which is useful in selecting new methods

For each new lot of control materials, new control values must be calculated, and acceptable ranges established. The values necessary for calculating the acceptable ranges are the mean and standard deviation. At least 20 samples are necessary for good statistical data.The mean is calculated by adding all of the values, and dividing by the number of values. The formula is: For example, suppose you wanted to find the mean of the values 4, 6, 2, 8, and 5. The mean is: The standard deviation (abbreviated s or SD) is calculated according to the following formula:That is, calculate the deviation from the mean for each point, square those results, sum them, divide by the number of points minus one, and finally take the square root. For example, the deviations from the mean in the above example are -1, 1, -3, 3, and 0. The squared deviations are 1, 1, 9, 9, and 0. The standard deviation is therefore: The standard deviation will be larger if the data are spread out and smaller if the data are closely clustered about the mean.

Quality control charts are examined to see if there are problems in the procedure being tested. The Westgard rules are one tool that can help to determine whether there is a problem, and whether that problem is due to random or systematic error.The six Westgard multi-rules are: 12S rule: this rule applies when at least one result falls more than two standard deviations above or below the mean. This is a signal that the run must be examined in further detail, and does not in itself warrant discarding the run. However, if all of the results are with in 2s, the run should be accepted. 13s rule: this rule applies when a result falls outside of the 3s limit. The run is rejected, and a random error has probably occurred. 22S rule: this rule applies when two consecutive results exceed the +2 or the -2 standard deviation limit. The controls could be normal, abnormal, or one of each. A violation of this rule usually indicates a systematic error. The run is rejected. R4S rule: this rule applies when the difference between the highest and lowest result of a run exceeds 4 standard deviations. This rule detects random errors. The run is rejected. 41S rule: this rule applies when four consecutive control samples all exceed the +1 or the -1 limit. The controls could be normal, abnormal, or a combination of the two. This rule detects systematic errors. The run is rejected. 10x rule: this rule applies when 10 consecutive controls all fall on the same side of the mean, either above or below. This rule detects a systematic error. The run is rejected.Some labs choose not to use all of the Westgard rules; however, it is recommended that all labs use at least two rules, one that can detect systematic error and one that can detect random error.

Specialists in radioassay use radionuclides to determine the chemical makeup of body fluids such as blood and urine. Specialists in blood gas analysis evaluate lung and breathing function by levels of oxygen, carbon dioxide, pH, and hemoglobin with automated tests. Specialists in histology examine cellular and tissue samples using fixation, dehydration, embedding, microtomy, frozen sectioning, staining, and other similar techniques. Histology specialists licensed as technicians can perform specimen processing, embedding, cutting, staining, and frozen sectioning only under the general supervision of a director, supervisor, or technologist. Specialists in cytology process and interpret samples relating cytopathological disease. Non-gynecological cytology preparations can be screen by a specialist in cytology but final review and interpretation must be done by a physician.

Technicians perform laboratory testing under direct and general supervision, as required by the test and the conditions of the technician's license. Other duties include:Performing tests only as authorized by the director and the technician's licensed specialty.Following the laboratory's procedure for specimen handling and running testsParticipating in proficiency testing and demonstrating that proficiency samples are tested in the same manner as patient samplesFollowing quality control and instrument calibration policiesDocumenting corrective action taken when results exceed the laboratory's acceptable performance valuesIdentifying potential problems with tests or report resultsNotifying a technologist or supervisor if results are outside the laboratory's acceptable performance levels

Medical errors also occur in the analytic processes and systems of patient care. Analytic errors begin with problems in the transportation of medical samples for testing. These occur between the patient's location and the testing facility. They happen during the time between specimen collection and arrival in the testing facility. The possibility for analytic medical error continues through the analytic processes and procedures of medical testing. Analytic medical error also includes systems, processes, and procedures involved in the transmission and reporting of test results. These medical errors occur during the time the laboratory is directly involved in receiving, analyzing, and reporting test samples. Examples: Wrong transport storage or temperature Delay in transport Sample mixup during transport Acceptance of unacceptable samples that are insufficient, hemolyzed, or clotted Centrifugation, mixing, and other test sample preparation errors Wrong test procedures Test control errors Sample mixup during testing Outdated reagents Wrong reagents Test result mixup Transcription errors Data reporting process errors Result report delays

The setting is automated chemistry department, night shift, busy core laboratory for a hospital based outreach laboratory. A medical technologist who operates the automated chemistry analyzer on third shift encounters short samples a couple of times a night. When this happens, he runs as many of the ordered tests as he can and fills in the blank results with a comment indicating that a short sample occurred. As far as he knows there isn't a policy that addresses this problem directly.The test reports out with the results and the comments. The technologist does not have to change the physician order in any way and is providing the maximum results that can be reported for the specimen in a timely fashion. This is done as a matter of patient care and quality service. There has not ever been a complaint about this practice as far as he knows. Are there any additional steps this technologist should be taking?Correct Answer: The technologist should follow the procedures that the laboratory has in place for testing and billing samples for which there is no order or for ambiguous orders. If the policies do not seem to address his particular situation, he thinks there should be a separate policy to cover this situation or has a question about it, he should talk to his supervisor or to the laboratory compliance officerDiscussion: This choice addresses the problem in the most complete manner, in that the employee fulfills his responsibility to take action when he thinks there is a problem.

Ideally, a drug level would be monitored frequently and consistently, providing the clinician with a detailed pharmacokinetic profile over time. In reality, serum samples are often measured only during relatively infrequent clinic visits, meaning that many days or weeks may pass before a drug concentration 'snap-shot' is taken.

Are used to collect sterile blood samples from patients who may be septic (have bacteria or other organisms growing in their bloodstream). Different blood culture bottles are used for aerobic, anaerobic, and pediatric collections.

QC programs require the same sample to be tested every day testing is done. This type of sample is called a control. Controls, which are often purchased from manufacturers, use a human base to ensure the analytes being tested parallel human ranges. Manufacturers pool together many human blood samples to create the large volume needed for a lot number of control.

Before controls and patient samples can be run, testing instruments must first be calibrated. This requires standards. Standards are materials which contain accurately determined concentrations of an analyte that are used to either confirm a testing method's validity, or to make sure an instrument reads correctly. Calibrating an instrument allows every unknown patient sample or control to be analyzed from a measured starting point. Standards should not be used in place of daily controls because they do not measure or control other variables in the testing process such as operator technique or sample appropriateness.

Initial analysis of the peripheral blood picture is made in most clinical laboratories with an automated instrument. Samples are selected for further analysis when quantitative or qualitative abnormalities beyond a defined standard are found. The following are examples of quantitative RBC abnormalities that may prompt a blood smear review. Each laboratory, however, should develop its own guidelines: Hgb: < 8 or >18 g/dL (<10 or > 21g/dL in a newborn)Hct: <20% or > 60% in adults (<40% or >65% in a newborn)MCHC: <29 g/dLMCV: <69 femtoliters (fl) or >110flFlags generated by the hematology analyzer that indicate possible red cell abnormalities or spurious resultsAny of these findings should be followed up with a peripheral blood smear review.