Reinfusion of discard blood from venous access devices

To determine if clots are present in the initial 10 ml of blood routinely discarded from venous access devices (VADs) prior to blood sampling, and to determine if clots form in the discard blood specimen during the five minutes required to complete blood specimen sampling.

A pretest/post-test design.

A large, mid-Atlantic research institution.

A convenience sample of 50 adult patients with cancer (27 males and 23 females) with a median age of 60. A large sampling size variation existed among the different VADs.

Two 5 ml discard specimens were drawn into separate syringes. Syringe #1 was filtered immediately, and syringe #2 was filtered after a five-minute dwell time. Both samples were filtered through a 40 micron filter.

The presence or absence of clots.

Fifty percent (n = 25) of the VADs had clots present on the filter from syringe #1. The clots varied in length, width, depth, and diameter, which precluded a consistent measurement. The investigators were able to measure either the diameter or length, depending on the shape of the clots. The majority of the clots (n = 17) appeared to be shaped like the lumen of a catheter and varied from 0.1 cm to 1.2 cm in length. Six clots were round and varied in diameter from 1.6 mm to 2.8 mm. Only 4% (n = 2) of the VADs had clots in syringe #2, but those clots were much larger, measuring 8.3 mm and 18.4 mm.

The study addresses concerns of the investigators regarding the clinical practice of reinfusing discard blood obtained from VADs. Whether the clots present in the catheter and their reinfusion represent a significant risk to patient outcome is unclear.

Until further research is conducted and the degree of risk can be better defined, methods of drawing blood that require reinfusion of discard blood from VADs are not recommended.