title: Catheter-drawn blood cultures: is withdrawing the heparin lock beneficial?
abstract: OBJECTIVE
  To assess the potential benefit of withdrawing or flushing away the heparin lock before collecting blood for culture from a central venous catheter.
  
  
  METHODS
  We compared the contamination rates of 152 pairs of blood samples aspirated from central venous catheters in afebrile renal dialysis or cancer patients. We also assessed the antimicrobial effect of 2000 U of heparin in Bactec Plus Aerobic/F culture bottles inoculated with a volunteer's blood plus one of six common bloodstream pathogens.
  
  
  RESULTS
  There was no significant difference in contamination rates between first-drawn (26 of 152, 17.1%) and second-drawn (24 of 152, 15.8%) samples. There was no significance difference in yield (58 of 60 [97%] versus 52 of 53 [98%]) or time to flagging positive (16.6 versus 16.7 h) between the bottles with and without heparin.
  
  
  CONCLUSIONS
  Our results do not support the practice of withdrawing or flushing away the heparin lock before collecting blood for culture from a central venous catheter.
authors.affiliation: Microbiology Section Medlab Central Palmerston North New Zealand. richard.everts@nmhs.govt.nz
authors.forename: Richard
authors.initials: R
authors.lastname: Everts
authors.forename: Hamish
authors.initials: H
authors.lastname: Harding
mesh_terms: D000890:Anti-Infective Agents / Q000494:pharmacology; D001769:Blood / Q000382:microbiology*; D001800:Blood Specimen Collection / Q000379:methods*; D017848:Blood-Borne Pathogens; D002404:Catheterization; D002408:Catheters, Indwelling / Q000382:microbiology*; D004866:Equipment Contamination / Q000517:prevention & control*; D006493:Heparin / Q000494:pharmacology; D006801:Humans
chemical_list: D000890:Anti-Infective Agents; D006493:Heparin