title: Internal quality assurance in a clinical virology laboratory. II. Internal quality control.
abstract: OBJECTIVE
  In April 1991 additional quality control procedures were introduced into the virology section of the Clinical Microbiology and Public Health Laboratory, Cambridge. Internal quality control (IQC) samples were gradually included in the serological assays performed in the laboratory and supplemented kit controls and standard sera.
  
  
  METHODS
  From April 1991 to December 1993, 2421 IQC procedures were carried out with reference sera.
  
  
  RESULTS
  The IQC samples were evaluated according to the Westgard rules. Violations were recorded in 60 of 1808 (3.3%) controls and were highest in the IQC samples of complement fixation tests (25/312 (8%) of controls submitted for complement fixation tests).
  
  
  CONCLUSIONS
  The inclusion of IQC samples in the serological assays performed in the laboratory has highlighted batch to batch variation in commercial assays. The setting of acceptable limits for the IQC samples has increased confidence in the validity of assay results.
authors.affiliation: Clinical Microbiology and Public Health Laboratory, Addenbrooke's Hospital, Cambridge.
authors.forename: J J
authors.initials: JJ
authors.lastname: Gray
authors.forename: T G
authors.initials: TG
authors.lastname: Wreghitt
authors.forename: T A
authors.initials: TA
authors.lastname: McKee
authors.forename: P
authors.initials: P
authors.lastname: McIntyre
authors.forename: C E
authors.initials: CE
authors.lastname: Roth
authors.forename: D J
authors.initials: DJ
authors.lastname: Smith
authors.forename: G
authors.initials: G
authors.lastname: Sutehall
authors.forename: G
authors.initials: G
authors.lastname: Higgins
authors.forename: R
authors.initials: R
authors.lastname: Geraghty
authors.forename: R
authors.initials: R
authors.lastname: Whetstone
mesh_terms: D003168:Complement Fixation Tests / Q000592:standards; D004739:England; D004797:Enzyme-Linked Immunosorbent Assay / Q000592:standards; D015497:HIV-1 / Q000302:isolation & purification; D015498:HIV-2 / Q000302:isolation & purification; D006801:Humans; D007755:Laboratories, Hospital / Q000592:standards*; D011786:Quality Control; D014773:Virology / Q000592:standards*; D014780:Viruses / Q000302:isolation & purification