Sources of preanalytical error in primary health care : implications for patient safety

Abstract: Background Venous blood tests constitute an important part in the diagnosis and treatment of patients. However, test results are often viewed as objective values rather than the end result of a complex process. This has clinical importance since most errors arise before the sample reaches the laboratory. Such preanalytical errors affect patient safety and are often due to human mistakes in the collection and handling of the sample. The preanalytical performance of venous blood testing in primary health care, where the majority of the patients contact with care occurs, has not previously been reported.Aims To investigate venous blood sampling practices and the prevalence of haemolysed blood samples in primary health care.Methods A questionnaire investigated the collection and handling of venous blood samples in primary health care centres in two county councils and in two hospital clinical laboratories. Haemolysis index was used to evaluate the prevalence of haemolysed blood samples sent from primary health care centres, nursing homes and a hospital emergency department.Results and discussion The results indicate that recommended preanalytical procedures were not always followed in the surveyed primary health care centres. For example, only 54% reported to always use name and Swedish identification number, and 5% to use photo-ID, the two recommended means for patient identification. Only 12% reported to always label the test tubes prior to blood collection. This increases the possibility of sample mix-up. As few as 6% reported to always allow the patient to rest at least 15 minutes before blood collection, desirable for a correct test result. Only 31% reported to have filed an incident report regarding venous blood sampling, indicating underreporting of incidents in the preanalytical phase.Major differences in the prevalence of haemolysed blood samples were found. For example, samples collected in the primary health care centre with the highest prevalence of haemolysed samples were six times (95% CI 4.0 to 9.2) more often haemolysed compared to the centre with the lowest prevalence. The significant variation in haemolysed samples is likely to reflect varying preanalytical conditions.Conclusions This thesis indicates that the preanalytical procedure in primary health care is associated with an increased risk of errors with consequences for patient safety and care. Monitoring of haemolysis index could be a valuable tool for estimating preanalytical sample quality. Further studies and interventions aimed at the preanalytical phase in primary health care are clearly needed.