Specimen collection volumes for laboratory tests.

Abstract

Unnecessary tests, inefficient ordering practices, and collection of more blood than is required for testing contribute to iatrogenic anemia in hospitalized patients. Laboratories accredited by the College of American Pathologists are expected to review phlebotomy practices for specimen collection volumes periodically. To report specimen collection, analytic, and discard volumes for routine laboratory tests and to identify practice variables associated with overcollection and blood wastage. Clinical laboratories participating in the College of American Pathologists Q-Probes laboratory improvement program recorded collection container size, laboratory-defined requested volume, manufacturer-defined analytic volume, and average discard volume for routine complete blood cell counts and electrolyte panels ordered for patients in intensive care units. Participants provided information about their specimen collection, processing, and analytic practices in a questionnaire. A total of 140 public and private institutions. Overcollections for routine collections and for situations in which a reduced volume of specimen is collected, and average discard volume per tube. Laboratories collected a median of 2.76 mL (or 8.5 times) more than their instrument's analytic volume for routine complete blood cell counts and 1.75 mL (or 12 times) more than their instrument's analytic volume for routine electrolyte panels. For clinical situations in which reduced collection volumes were necessary, overcollection for the same analytes was 0.5 mL (3 times) and 0.44 mL (4.2 times), respectively. The median discard volume was 2.8 mL/tube for complete blood cell counts and 2.0 mL/tube for electrolyte panels. Specimen collection container size was directly associated with overcollections and discard volumes. Instrument analytic volume was not a determinant of blood wastage. Most laboratories can decrease collection volumes without compromising the ability of the laboratory to report a reliable and timely result. Use of smaller collection tubes can help reduce blood wastage.