Chemistry and haematology sample rejection and clinical impact in a tertiary laboratory in Cape Town

Clin Chem Lab Med. 2011 Oct 14;49(12):2047-50. doi: 10.1515/CCLM.2011.743.


Background: Recent publications report that up to 70% of total laboratory errors occur in the pre-analytical phase. Identification of specific problems highlights pre-analytic processes susceptible to errors. The rejection of unsuitable samples can lead to delayed turnaround time and affect patient care.

Methods: A retrospective audit was conducted investigating the rejection rate of routine blood specimens received at chemistry and haematology laboratories over a 2-week period. The reasons for rejection and potential clinical impact of these rejections were investigated. Thirty patient files were randomly selected and examined to assess the impact of these rejections on clinical care.

Results: A total of 32,910 specimens were received during the study period, of which 481 were rejected, giving a rejection rate of 1.46%. The main reasons for rejection were inappropriate clotting (30%) and inadequate sample volume (22%). Only 51.7% of rejected samples were repeated and the average time for a repeat sample to reach the laboratory was about 5 days (121 h). Of the repeated samples, 5.1% had results within critical values. Examination of patient folders showed that in 40% of cases the rejection of samples had an impact on patient care.

Conclusions: The evaluation of pre-analytical processes in the laboratory, with regard to sample rejection, allowed one to identify problem areas where improvement is necessary. Rejected samples due to factors out of the laboratory's control had a definite impact on patient care and can thus affect customer satisfaction. Clinicians should be aware of these factors to prevent such rejections.

MeSH terms

  • Blood Coagulation
  • Blood Specimen Collection* / standards
  • Chemistry Techniques, Analytical
  • Humans
  • Laboratories, Hospital / standards
  • Medical Errors / prevention & control
  • Retrospective Studies
  • South Africa
  • Specimen Handling
  • Time Factors