Please review our previous thread on specimen collection and the comment on discard tubes. Except for “butterfly” infusion sets, when we use a discard tube to compensate for air in the tubing, discard tubes are contraindicate. See McGlasson DL, More L, Best HA, et al. Drawing specimens for coagulation testing: is a second tube necessary? Clin Lab Sci 1999;12:137-9.
I vividly recall a presentation by Dr. Dorothy Adcock at a Temple University coagulation meeting in 1997 or 1998 in which she gave results of a study she completed with Dr. Richard Marlar. During Q&A, I naively asked whether she could comment on the effect of traumatic venipuncture from her study.
Dr. Adcock is a gracious person. She smiled and said her IRB would not approve that part of the study, but they were thinking of repeating it using medical students as their phlebotomists. That brought a laugh.
In fact, for better or worse, several studies cited in the McGlasson article conclude no need for discard tubes, and we have generalized the results to include traumatic sticks, adding we should avoid traumatic sticks. The policy is supported by the CLSI standard H21-A4, so we generally advise to eliminate the use of the discard tube.
I’d love to see some additional opinions.