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Dear Mr. Abdulfattah Hussein Saleh Zolait,
== The venous blood samples, the most common biological sample type in hospitals. Other kinds of biological samples include arterial blood for blood gas analysis, and capillary blood, most often used for measurement of plasma glucose, hemoglobin or C-reactive protein. Samples are also collected for anatomical pathology (surgical and cytological).
== Venous blood samples are mainly used for clinical chemistry analysis (hematology, coagulation and general clinical chemistry), but can also be used, e.g. for microbiological diagnostics and pre-transfusion testing. General clinical chemistry analyses can also be carried out on other biological sample types, such as urine and cerebrospinal fluid. Laboratory testing can be performed outside the laboratory, usually referred to as point-of care testing.
== In epidemiology, Medical error means the risk, and usually it is related to risk factor, i.e. a component that confers an increased probability of disease. Risk is linked to patient safety, as the risk of error. The prediction and prevention of risks are used to reduce medical error, for example in laboratories.
== The way one perceives errors and risks is important; it aims the investigation for causes, and thus possibilities for prevention, of errors. If searching for human error or lack of routines, one will probably find both, if you look closely enough. There are often combinations of several factors that give rise to an error. Thus, a “fix-all” solution is seldom sufficient to prevent an accident from happening again.
== The Quality Specimen is simply the specimen which accurately reflects the in vivo situation of the patient at the time of collection. Because blood is a 'living fluid', collection of a quality specimen and delivery of this to the laboratory is far from easy. Most errors in the venous blood testing process are pre-analytical, i.e. they occur before the sample reaches the laboratory. Unlike the laboratory analysis, the pre-analytical phase involves several error-prone manual tasks not easily avoided with technological solutions.
== Many factors can combine to bring about significant change in the specimen from the point of collection through to the time of analysis. The most common causes of sub-optimal specimens and their rejection by the laboratory are hemolysis, clotted specimens, ID error and poor quality specimens arising from IV line collections
=1= In contrast to laboratory testing, analytical error is common in point-of-care testing. One important reason is that this testing is not always covered by quality control systems used in the laboratory. Another is that staff not primarily working with laboratory testing often carries out these analyses. Pre-analytical errors are a problem, including patient identification. Post-analytical errors are also an issue, since many point-of-care instruments are not connected to the laboratory data system.
=2= Other important sources of pre-analytical error not related to human mistakes include medications, which can cause errors through analytical (in vitro) or biological (in vivo) effects, and biological variation, which is the major source of variation for certain analyses. The biological variation consists of two parts. The intra-individual part is the normal variation of the analyzed substance in each individual during the day. The inter-individual part is the normal variation of the analyzed substance between individuals.
=3= The total uncertainty in the test result due to pre-analytical reasons can be calculated. For example, differences in pre-analytical procedures can explain up to 41%of the variation of prevalence of hypercholesterolemia. Errors prior to ordering of the test (pre pre-analytical) like over-utilization of laboratory tests are difficult to measure, since a major part takes place in the brain of the physician.
=4= The current way of viewing error is as system errors, meaning that most errors are a product of failed organizational structures, rather than individual mistakes. An 85-15 rule has even been suggested, meaning that 85%of all errors or problems are caused by systems or processes and only 15% by an individual person. This is a very favorable way of looking at errors for the individual, since this view is less likely to produce blaming and feelings of guilt, and paves the way for constructive changes in practice.
=5= Improving the accuracy of patient identification is the highest priority for patient safety. Patient identification at venous blood sample is an important source of error in blood transfusions, due tonon-compliance with guidelines.
- Mistakes in the patient identification procedure beforevenous blood sample can be responsible for up to 25% of all pre-analytical errors.
- Further, in up to 75%of all blood transfusions, the valid identification procedure is not followed. Mistakes inthe identification and labeling procedure in blood testing can result in serious adverseevents, including the death of the patient.
- In fact, 1 out of18identification errors in laboratory testing result in an adverse event, which would imply at least 160000adverse events annually in the United States.
- Mistakes in patient identification often originate in manual tasks not easily avoided with technological solutions. Patient identification and labeling of test tubes have importance in all areas of health care.
- Mislabeling of test tubes for blood transfusion pre-testing, a highly regulated task, is reported to occur in median in1 out of 165–200test tubes. Mislabeling is responsible for 50% of all identification errors in the total testing process.
- One important source of pre-analytical error is incorrect or incomplete information on the test request or on the test tube label. In fact, erroneous requests and labels may account for more than two thirdsof all rejected samples in the laboratory
=6= Prolonged venous stasis during venous blood sample can also have clinically significant effects on the test result, with a similar physiological background as for insufficient patient rest. For example, prolonged venous stasis can cause a 7% variation in the prevalence in hypercholesterolemia. If a sample for analysis of cholesterol is collected without stasis before the introduction of a medication, and with prolonged stasis at the follow up testing, the cholesterol value might be falsely high, and an unnecessary medication could be introduced. Further, prolonged stasis, and also hand clenching, can lead to local hypoxia and thus acidosis, which can affect for example potassium measurements.
=7= The vertical test tube storage after sample collection, and use of a proper coagulation of serum samples can be encountered pre-analytical errors:
- Inadequate flushing of the IV line is a common cause of contamination of specimens with electrolytes, glucose or other substances causing laboratory error.
- The presence of infusion fluid in the specimen will of course introduce a dilution error which will affect all test results. Regardless of whether the specimen is acquired via syringe collection or direct evacuated collection, the line should first be flushed using sterile saline with a minimum of2.5 times the 'dead space' of the catheter. Note that the actual dead space may vary considerably according to the device type.
- Inversion of citrated, heparinized and EDTA-containing test tubes is recommended to adequately mix blood with the anticoagulant.
- Inadequate inversion of test tubes can cause clotting of the blood, reported to constitute an important part of pre-analytical errors in blood sample. The sequence of the test tubes during sampling is important to avoid contamination by anticoagulants.
- Both time before centrifugation and storage temperature can produce pre-analytical errors. Venous blood sampling from peripheral venous catheters is known to be prone to hemolysis. The amount of this hemolysis is dependent on the size of the test tube that is used.
- Blood cells in general and red blood cells in particular are fragile and susceptible to rupture due to mechanical trauma, osmotic shock (exposure to non-isotonic fluids) and exposure to temperature extremes (e.g. during transportation to the laboratory). Hemolysis is one of the most common causes of sub-optimal specimens leading to laboratory error.
- Whilst gross hemolysis is rarely missed, clinically meaningful variations of some laboratory tests have been observed in specimens where hemolysis is mild or almost undetectable. An example of this would be the production of a normal potassium result for a hypokalemic specimen.
- The Use of large bore syringes in conjunction with small gauge needles adds to the mechanical trauma placed on the blood cells.
- Lysis of red cells due to exposure to liquid skin antiseptic agent is also common when insufficient time is allowed for the skin preparation agent to dry.
- Apart from errors arising from contamination of serum and plasma with intracellular contents of red cells, it should be noted that hemolysis can also lead to significant errors in coagulation testing. Levels of hemolysis less than1% have been shown to impact significantly on test result accuracy for routine coagulation tests such as INR, and aPTT7. Adverse handling of the specimen leading to red cell rupture is also likely to damage platelets and facilitate increased activation of the latter.
- Fortunately, many modern analyzers automatically screen for hemolysis. Nevertheless, this remains as a significant source of error.
=9= Transport of samples to the laboratory can give rise to clinically important errors if transport conditions are not optimized. Prolonged transport time contribute to a prolonged turnaround time, and thus delayed patient care.
- If the analysis is centralized to another hospital, the sample may have to be transported, e.g. by car, to the laboratory, which can have effects on test results.
- In hospitals, test tubes are often transported by pneumatic tube system transport (PTST), since this reduces laboratory turnaround time and labor. A PTST consists of a system of tubes, linking stations on wards and laboratories together.
- Hematology, coagulation, and chemistry parameters, such as red and white blood cell counts, Prothrombin time, and potassium and sodium measurements, have been reported to be mainly unaffected by PTST.
=10= A common source of analytical errors is interferences, for example in immunoassays. Quality control programs, such as proficiency testing and technical evolution, have reduced analytical errors over the years. The error-prone internal manual handling of test tubes can be fully automated in the near future. Further quality improvement efforts will therefore be most effective if applied on the pre- and post-analytical phases of the TTP.
=11= The post-analytical step mainly concerns the delivering of a test result. Error-prone steps in the transmission of information are eliminated and can therefore improve the Post-analytical step. If connected to the patient record, the error-prone delivery of the paper-based test result should be eliminated. The post-analytical step includes the post post-analytical step, which involves properly interpreting and taking appropriate action to a test result. The post post-analytical step can also give rise to important errors.
== The total testing process (TTP) is the total process from the ordering of a test to the interpretation of a test result. The TTP starts and ends with the patient, and can be subdivided into three distinctive phases: the pre-analytical step (before the analysis), the analytical step (the actual analysis) and the post-analytical step (after the analysis),
== Errors can occur in every step of the TTP. Of all errors in the TTP, approximately one fourth have consequences for the patient. These consequences include a delayed test result or renewed sample collection. In a case report, one patient had15 consultations,77 laboratory tests and a computer tomography, as a result of one erroneous test result.
== Studies today suggest that 0.01 to0.5%of all test results are erroneous. The actual error rate is probably higher, since estimating errors in the TTP is a difficult task. Many errors are also detected by quality control systems in the laboratories and corrected before they produce an erroneous test result. Both detected and undetected errors may cause unnecessary and costly investigations and consequences for the patient. Further, these errors might not be detected next time.
== It is evident that the majority of all errors in the TTP are of pre-analytical origin, i.e. they occur before the sample arrives in the laboratory. Previous reports account for 46–68%.Of all blood specimens sent to the laboratory for analysis, 0.1–10%is erroneous for pre-analytical reasons.
== Even if the pre-analytical phase is responsible for the majority of the errors in the TTP, the analytical and post- analytical phases also contribute to errors with consequences for patient Care. Of all errors in the TTP,7–13% have been reported to occur in the analytical, and19–47% in the post-analytical phases. Errors in the analytical phase can be either systematic errors (bias), or random errors (imprecision). The analytical imprecision is dependent on the biological variation, since a small biological variation will demand a low analytical imprecision
== The error rates are greatly dependent on the method for error detection that has been used. The better the method, the more errors it will find. Previously used methods include registration of errors in the laboratory, registration of errors by the responsible physician or by a multidisciplinary team, direct observation and classifying error reports. It has been suggested that 75% of all errors produce test results within the reference intervals. It is of utmost importance that all test results are judged against the patient’s clinical picture, with the limitations of a laboratory test in mind, since erroneous test results otherwise can lead to serious consequences
== However, the distribution of error, with the majority originating in the pre-analytical phase, is fairly constant and is independent of the study design, country, definition of error, or method used for data collection. Pre-analytical errors are largely attributable to human mistakes and the majority of these errors are preventable. This is understandable, since the pre-analytical phase involves much more human handling, compared to the analytical and post-analytical phases.
== The relative frequency of errors in the TTP may seem rather low, but many samples are collected each year, and a large number of analyses are conducted on these samples. Laboratory tests are stated to generally have a major impact on medical decisions and increase the certainty of the diagnosis. Thus, reduction of errors is important for everyone involved in the TTP, since the total number of errors with consequences for patient care, and the accompanying excess expense, become very high.
Best wishes,
Lubna Al-Sharif
I did not recognize which type of blood test and cells your are talking about ! could you please paraphrase the question?Anyhow, the error rate on both the biopsy and blood testing is about20%
The question is not clear, please rephrase it.
MR ABD the question is not clear
error in routine blood testing is high due to miss calibration and mostly wriitn work, the test maybe done right and the device is caalibrated but its written wrong so the most important part in a the bussiniss is review and review.about cell dyn its a good blood counter but as every device need good maitainance, control abd calibration.
