False-positive crystals in urine from contamination by Multistix 10 SG reagent strips for urinalysis.

Dipstick testing of urine is commonly performed as part of point-of-care testing. Unless separate aliquots are used for dipstick testing, substances may be eluted from the test strip and contaminate patient samples. Such contamination has the potential to lead to interference in subsequent assays if the contaminated specimen is sent to the central laboratory for additional testing.

Comparison of glass K3EDTA versus plastic K2EDTA blood-drawing tubes for complete blood counts, reticulocyte counts, and white blood cell differentials.

Blood-drawing tubes made from plastic containing K2EDTA as an anticoagulant are gaining widespread use in clinical hematology. We compared complete blood count parameters, reticulocyte counts, white blood cell differentials, and flagging rates obtained with Becton Dickinson Vacutainer K3EDTA glass tubes and Vacutainer K2EDTA Plus plastic tubes and found only slight discrepancies in the results obtained with the two tube types. Although some parameter values obtained with K3EDTA glass tubes were significantly lower than those obtained with K2EDTA plastic tubes, many of these differences could be explained by the known effects of the liquid K3EDTA anticoagulant.