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Blood cultures from central lines

Does anyone have any documentation regarding obtaining blood cultures from central lines?  Should injection caps be removed prior to obtaining blood sample to prevent any false positives from cap contamination?  I have some documentation that supports this but just want to know what everyone else thinks/does.  Thanks

Our policy is to remove the

Our policy is to remove the injection cap for all blood draws from a central line then place a new cap after.

Valorie Dunn,BSN, RN, CRNI, PLNC

Yes, we remove the injection

Yes, we remove the injection caps, swab the hub and do not draw off a waste from line.

Anne Marie Frey
blood cultures

Actually, we just looked at this as a research project for our CLABSI prevention is what we found out.  There are several schools of thought here.  1.  Remove the cap and draw from the hub;  2.  Change the cap PRIOR to drawing the culutre; or 3. Draw the culture through the cap.  There is NOT strong evidence to support any one method of obtaining blood cultures from CVCs.  Many people say remove the needleless cap because that way you eliminate organisms in or on the cap from contaminating your culture specimen.  Evidence?  No comparative studies published that I could locate. Possibly makes some sense, though.  The second method where the cap is changed prior to drawing the culture was supported by one very small study that was presented at INS last year.  The conclusion was that contaminated [false positive] blood cultures cost more to treat than a new cap would cost.  Interesting and less false positives with a new cap, but this was a small study.  Central Line Blood Sampling: The Impact of Changing the Needleless Caps Prior to Collection Poster presented at INS conference, May, 2008 The third method, cleaning the needleless cap has been studied in multiple studies and correct cleaning is shown to be effective in reducing organisms when entering a line via the needleless cap.  However, the effect on blood cultures drawn this way has not been published. 

There are also national guidelines for blood cultures from the Clinical and Laboratory Standards Institute from 2007.  These only mention a higher contamination rate with cultures drawn from lines vs. peripherally. 

Anyway, unless someone has seen more evidence to prove any one of these methods is far superior, I think that there is not enough data to support any one method, INCLUDING removing the needleless cap and drawing directly from the hub. this means that you choose the method that works for your institution where you monitor what the cultures drawn from CVCs grow compared to peripheral cultures and rate of false positives with whatever method you use.

By the way, those of you who do the cap removal method [and keep in mind, I am not saying it is wrong or right!!], do you clean the actual hub with anything?  If so, what, how, and why? 

Some food for thought!!

Anne Marie Frey

The Children's Hospital of Philadelphia

Anne Marie Frey RN, BSN, CRNI, VA-BC
Clinical Expert
Vascular Access Service: I.V. Team
The Children's Hospital of Philadelphia
[email protected]

BC from central lines

Nice post Anne Marie,

Similar to information we have found.

The following pertains to patients on long term HPN with implanted catheters.

We do not remove the cap

We do not discard any blood when taking the BC

We do change the cap after the blood culture draw

We do a peripheral BC at the same time.


For those that change the cap prior to the BC, do you discard or not?  Do you change the cap after the BC?

RA Nishikawa, Pharm. D., BCNSP, FCSHP
Coordinator, Clinical Services
Director of Research
Nutrishare, Inc.
Elk Grove, CA

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