Phlebotomy: 25 Gauge Needle Question

[pagandeva2000]

I have been drawing blood as a phlebotomist for over 15 years before becoming a nurse. I was always told by lab techs and other nurses that drawing blood from a 25 gauge butterfly needle can hemolyze the blood, so, I would use size 23.

Now, working occasionally in the Coumadin clinic, I am encountering patients who I really cannot obtain a sample, and today, I had to resort to using a 25 gauge so that I would not blow the veins of this frail, elderly patient. The sample did make it to the lab, and a successful reading came, but I am concerned, because I see many patients like this, whose veins are blown from many hospital admissions and frequent visits to the labs and clinic.

What does anyone know about this? Does, in fact, the 25 gauge needle ruin the sample? Thanks!

[white hat lady]

I've been a Medical Technologist for over 20 years and am now a RN. In the lab I work in, the concern with the hemolysis of a sample is when the chemistry tests are affected. Slight hemolysis is not as significant as severe...and it usually boils down to collection. The larger the number of the guage, the smaller the bore of the needle. As blood flows while being drawn, there's just a greater chance of some hemolysis when a smaller bore needle is used. Using small needles, or butterflies are okay especially with babies and children, or even those patients that are difficult to draw. I'd rather have a slightly hemolyzed sample than no sample at all. The lab usually comments on the degree of hemolysis and docs are aware, or made aware of what tests are affected by hemolysis.

[illinois22]

I'm a phlebotomist as well as a BSN nursing student. At our facility, we try to avoid 25g needles if possible, especially if we are using them for a CBC, SED rate... basically something where RBC structure/morphology really matters. However, we do use them on difficult veins and small children. The rule we consistently use, however, is that if we use a 25g needle, we never draw them using a vacuum-based system; we use a syringe (usually a 3mL syringe as opposed to a 6 or 12 because the 3 tends not to cause the veins to collapse as easily). By using the syringe, it makes it possible to pull back with the least force needed to get blood out of the vein. With the vacuum tubes, there is no control over the force of the suction. After drawing into a syringe, we have transfer devices that screw on to the top of the syringes via a luer-lock system, and we can pop tubes onto that transfer device.