title: Analysis of factors influencing the generation of unqualified clinical samples and measures to prevent this generation.
abstract: BACKGROUND
  We investigated the influence of pre-analytical factors on the results of clinical tests and thereby analyzed approaches to improve quality management in clinical laboratories.
  
  
  METHODS
  Unqualified clinical samples were selected from all the samples received at our clinical laboratory. The data were collected for 2009 and 2010, i.e., the years before and after the establishment of the laboratory quality management system. The rate and causes of generation of unqualified samples were analyzed, and measures to improve the laboratory practices were studied and implemented.
  
  
  RESULTS
  A total of 1,051 unqualified samples were identified from among the 553,158 samples (the overall incidence rate of unqualified samples was 0.19%). The number of unqualified samples substantially varied according to the nature of the sample, and clinical samples collected for routine blood tests or coagulation tests were the predominant unqualified samples. The main causes of generation of unqualified samples were insufficient sample volumes and improper methods of mixing the samples. The rate of generation of unqualified samples decreased significantly after the implementation of improvement measures (0.26% in 2009 vs. 0.13% in 2010, P<0.001).
  
  
  CONCLUSIONS
  The number of unqualified samples decreased significantly after the establishment of the laboratory quality management system, which promoted active communication among and training of the clinical staff to reduce the occurrence of pre-analytical errors. Comprehensive control of pre-analytical factors is an important approach in improving the clinical laboratory practices.
authors.affiliation: Department of Laboratory Medicine, First Affiliated Hospital of Chongqing Medical University, Chongqing, P.R. China.
authors.forename: Xiaofei
authors.initials: X
authors.lastname: Lai
authors.forename: Ping
authors.initials: P
authors.lastname: Yang
authors.forename: Yuhong
authors.initials: Y
authors.lastname: Zhang
authors.forename: Ju
authors.initials: J
authors.lastname: Cao
authors.forename: Liping
authors.initials: L
authors.lastname: Zhang
mesh_terms: D019411:Clinical Laboratory Techniques / Q000592:standards; D003951:Diagnostic Errors / Q000706:statistics & numerical data; D006801:Humans; D007755:Laboratories, Hospital / Q000592:standards*; D013048:Specimen Handling / Q000592:standards