Vascular access devices (VAD) include a variety of infusion catheters and ports. The most common device is inserted in the arm or hand and provides easy access to a patient's circulatory system for administering fluids and medications. Occasionally, blood specimens are drawn from a VAD if a direct venipuncture is not feasible; however, the potential for specimen hemolysis or contamination with fluids or medications is increased when a specimen is collected from a VAD. Phlebotomists are not usually authorized to collect these specimens unless they have completed thorough and documented training. However, phlebotomists may sometimes assist when a clinical person who has been adequately trained collects blood from a VAD. If you are present, ensure that the person performing the collection flushes the line correctly (according to facility and manufacturer's guidelines) to avoid contamination and/or dilution of the specimen. The Clinical and Laboratory Standards Institute (CLSI) recommends this procedure2:
- If a specimen is collected for drug levels, the specimen must be collected from a catheter lumen not being used for infusion of the same drug. Withdraw a discard amount equal to two times the dead-space volume for noncoagulation testing. When drawing coagulation studies from a catheter lumen where anticoagulation therapy had been infusing, withdraw six times the dead-space volume. As a general guideline, 5 mL of blood may be a sufficient discard volume for most central lines; however, some central lines require up to 11 mL as a discard volume. When drawing coagulation studies, they know the dead-space volume to ensure accurate coagulation results. If drawing directly into tubes, use a plain, nonadditive tube or a tube of the same type as the first tube (This tube will be discarded).
- Obtain the specimen. If the specimen was obtained using a syringe, a safety transfer device must be used to transfer the specimen into the blood collection tube(s); a needle must not be used.
- Flush the VAD following facility and manufacturer's guidelines.
- Make a notation in the patient record that the specimen was collected through a VAD.
2. Clinical and Laboratory Standards Institute (CLSI). (2017). Collection of Diagnostic Venous Blood Specimens. (7th ed.) CLSI.
