Clinical Laboratory Errors: Source & Rectification

E L Nagasree & Prof K S Ratnakar

Medical laboratory science is largely dependent on the use of sophisticated instruments and techniques with the application of theoretical knowledge to perform complex procedures on tissue specimens, blood samples and other body fluids. The tests and procedures that medical laboratory technologists perform provide critical information enabling doctors to diagnose, treat and monitor patient's conditions.

Patient safety is influenced by the frequency and seriousness of errors that occur in the healthcare system. It is essential to identify critical performance measures in laboratory medicine and to describe error rates of these measures. Patient safety thereby can be improved by decreasing these errors. It has been identified that error rates for pre-analytical and post-analytical performance measures are higher, when compared to analytical measures.

Performance measures that are critical to evaluate and play a significant role in patient care can be selected. The resource requirement needed for successful implementation and long-term use of a performance measures influence the choice.

Eight performances are identified: (a) Customer satisfaction (b)Test turn-around time (TAT) (c) Patient identification (d) Specimen acceptability (e) Proficiency testing (f) Critical value reporting (g) Blood product wastage (h) Blood culture contamination, covering pre-analytical and post-analytical process.

The critical parameters such as patient identification, specimen rejection, blood culture contamination evaluate pre-analytic steps, critical value reporting and blood product wastage evaluate, post-analytical steps and TAT, and customer dissatisfaction evaluate the entire testing process. The list has been developed to include a performance measure for each of the four major disciplines of laboratory medicine, namely, biochemistry, haematology, transfusion medicine and microbiology. However, some performance measures such as specimen rejection or TAT can be implemented easily in two or more of the major disciplines.

Other performance measures apply to the entire clinical laboratory and include customer satisfaction, critical value reporting, patient identification and proficiency testing. Blood product wastage and blood culture contamination are performance measures that are specific to the discipline of transfusion medicine and microbiology, respectively. Another component that affects performance measure is transit time of samples to the laboratory.

Performance Measures

A) Customer Satisfaction: Customer satisfaction and clinical laboratory users are of three different groups: 1) Out patient 2) Consultant 3) Nursing personnel. The important attributes with regard to customer satisfaction are accuracy of laboratory results and TAT. The choice of accuracy of result emphasises the importance of proficiency testing as a critical performance measure essential for all laboratory tests.

When satisfaction level of nursing staff and physician is measured, it is noticed that the two attributes that serve as the most important clinical laboratory service variables are accuracy of results and TAT. Physicians valued accuracy more, whereas nursing staff identified test TAT. Most importantly, the dissatisfaction level is higher in nursing staff than in physicians. Others attributes which effect satisfaction level of nursing staff are laboratory personnel availability, prompt answering of telephone calls and courtesy extended to nursing staff. The above mentioned attributes play a vital role in satisfaction levels.

B) TAT: Laboratory test TATs are the most important performance measures for many clinical laboratory users. However, it is common for laboratories to hear from dissatisfied users that their test TATs generally are not satisfactory enough. It is been observed that physician goals for the TATs are shorter than laboratory standards and established practice for routine analysis such as electrolytes, creatinine, CSF, Hb, platelet count for patients in the emergency department.

The choices of a location, a test, a specimen type, or a test priority are surrogates for the entire scope of testing that laboratories perform. Unfortunately, laboratories frequently try to improve TATs for a specific test, a specific location, or a specific specimen type by immediately identifying and assaying those specimen in question, thereby extending the TATs of all other tests. It has been noticed that results needed for early nursing rounds generally fail to meet clinician goals. Clinicians believe that prolonged TATs delay treatment in emergency cases and decision making in ICU patients.

The most important action to improve TATs is for the laboratories to evolve a strategy and devote proper attention and chanalise resources to affect improvement.

1) Once the laboratory staff has taken the challenges to improve TATs, it is important that proper ambience is provided.
2) A flow diagram of the present testing process should be made so that there is an understanding of what is currently being done.
3) Every process should be investigated and faster ways of performing the processes should be adopted.
4) Even the most fundamental process of performing Special Tertiary Admissions Test (STAT) test should be challenged, as STAT requires the resource intensive interruption of testing.

Following are probably the areas for reducing TATs for tests:

I) Pre-analytical

a) Test selection and order - raised online
1) To ensure customised template for rapid ordering and standard.
b) Specimen collection and delivery
1) Use bar codes for vacutainer.
2) Reduce delay in transit of sample to lab.
3) Using appropriate vacutainer for respective test.

II) Analytical

a) Use bar code readers, that interface analyses with the software.
b) Sample directly from specimen container.
c) Use automatic repeats for abnormal values.
d) By reducing clinical work of entry in the lab.

III) Post-analytical

1) Interfacing of equipment for transmission of data immediately after processing.
2) Automation that would help to view results by the end users (ICU or wards) at one point at their work stations.

The laboratories commonly consider measuring TATs is the interval from accessing the specimen until the result is available. It is essential that TATs is defined from the time the test is ordered to the time the test results are documented and made available to the caregiver.

Patient Identification

Patient identification is an important parameter in laboratory services. Improper patient identification can lead to errors in reporting with fatal outcome and grave consequences.

Errors in patient identification can be reduced by having a unique identification number of individual patients. Errors while labeling could be reduced by using bar codes for the sample vacutainers and sample containers. Necessary training of staff of phlebotomy and nursing is essential to avoid errors in patient identification.

Proficiency Testing

This is useful for clinical laboratories to document and to improve the analytic performance of laboratory tests required for the patient care. Laboratories need to be enrolled with national and international bodies for proficiency testing programme. Some of the most frequent causes for failure in proficiency testing are clinical errors, calibration errors, random errors and errors caused by faulty testing material. It is recommended to take necessary action when results for an analyte are beyond 2 SD (Standard Deviation) from the mean value rather wait for a failure to occur.

Specimen Rejection

Appropriate patient specimens are required for accurate and precise laboratory results. Cause of specimen rejection could be due to collection in improper vacutainer, insufficient sample, hemolysis of sample or clotting of the sample. Specimen rejection may require patients to return to the phlebotomy site for replacement, especially for out-patient. The most frequently-cited reason for specimen rejection in biochemistry is haemolysis. In haematology, the most frequent reason for rejection is clotting of the specimen especially in paediatric cases. Rate of sample rejection is dependent on the personnel involved in collection of the sample. However, laboratory personnel has the lowest percentage of rejected specimen when compared to nursing staff.

Critical Value Reporting

Critical values, sometimes called 'panic values' or 'alarming values', have been implemented in all clinical laboratories. Critical values are laboratory result that indicate a life-threatening situation and require immediate intervention for the patient to survive. Hence, it is important to communicate these results immediately to the proper caregiver so that patient can receive appropriate treatment without delay. The most common analytes for critical values are limits of each analytes that constitute a critical value (normal range), the person associated with reporting or receiving the values, the time required to inform the critical value to the consult. The amount of time required for notification of critical value and the number of telephone calls to the concerned are important for the data to monitor the performance measure.

An action that may improve prompt reporting is to allow physicians, registrars, nurses and ward secretaries to receive the critical value report. For a number of years many laboratories have suggested that critical value call should be automated so that the responsible caregiver is automatically notified of the value. Cell phones and paging can be used for this purpose.

When critical values are verbally reported, the results must be written down and read back by the person who has received and noted the verbal result. It is been observed that there is high error rate involving values, patient names, results, test and specimen.

Blood Utilisation

Blood and blood products frequently are the most costly items in a typical laboratory budget. Due to increasing regulator requirements for testing, these products and an ever-increasing number of tested products are rejected from potential use. Hardly any hospital has full supply of the products they require throughout the year, thereby causing shortages that commonly delay surgical procedures, especially during holidays or times of medical emergencies. For this reason, it is important to ensure that all blood and blood products sent to hospitals are used for patients and do not get expired.

Cancelled orders represent the most frequent cause of wastage, accounting for nearly half of the lost units. Monitoring wastage and outdating, notifying physicians of their errors and presenting fiscal information of wastage and outdating to the transfusion committee are successful strategies to reduce errors.

Blood Culture Contamination

It is been observed that the most common contamination of patient sample is coagulase negative staphylococcus. Specimen collection variable associated with significantly lower contamination rates include use of a dedicated phlebotomy service, use of tincture of iodine for skin disinfection, and application of an antiseptic to the top of the collection device before inoculation. Culture parameters associated with higher contamination rates include microbial growth from a single specimen, isolation of certain microbial species, and longer time to detect growth in culture.

Other potential performance measure would be dispatch of reports. The time duration required for availability of results to the end user, and delay in this aspect would effect the entire process. Online reporting with electronic signature would reduce delay in dispatch of reports from laboratory to the end user.

Modern care depends heavily on the laboratory data. Both precision and accuracy are mandatory. While quality assurance programmes oversee the precision aspect, the diagnostic services need to look into the most vital area of laboratory errors and the related issues. This short communication highlights the areas that focus our attention on this aspect to obviate recurrence of such errors and improve the services.

Hospital Study

Analysis of these parameters has been carried out at Global Hospital, a tertiary care) hospital and the results are given in the table. Though the percentage values are definitely indicative of efficiency, target success possibly requires, at least in some areas, total satisfaction.

While E L Nagasree is Quality Manager, Global Hospital, Hyderabad, K S Ratnakar is Chief of Lab Services with the same hospital.
Email: nagasree_el@yahoo.com & ratnakarkamaraju@yahoo.com