Q&A column

To use a CAP-provided assessment course beyond its expiration date or to customize it for your laboratory, import a copy of the course using the CourseBuilder tool. Your laboratory will have access to that copy of the course as long as it has a subscription to the program. You can also create your own quizzes using the CourseBuilder tool.

Centers for Medicare and Medicaid Services. What Do I Need to Do to Assess Personnel Competency? November 2012. http://www.cms.gov/Regulations-and-Guidance/Legislation/CLIA/downloads/CLIA_CompBrochure_508.pdf

Clinical and Laboratory Standards Institute. QMS03-A3: Training and Competence Assessment; Approved Guideline, 3rd ed.; 2009.

Carol Netols, MT(ASCP)SBB
Technical Specialist
Laboratory Accreditation Services
College of American Pathologists
Northfield, Ill.

Q. Are there red blood cell parameters, such as RBC count or mean corpuscular volume, that can affect a platelet estimate? When determining a platelet estimate, should we always look at the same area of the slide regardless of the patient’s RBC, hematocrit and hemoglobin levels, and indices results?

A. A false increase in a platelet count can occur in the setting of microcytic RBCs, RBC inclusions such as Pappenheimer bodies, and RBC fragmentations.^1,2

When performing a platelet estimate, it is recommended that the entire blood smear, including the feathered edge, lateral edges, readable area, and thick area, be examined first under a 10× dry objective, looking for clumps of platelets.³ As a rule of thumb, platelet estimates are then performed using a 100× oil objective in an area of the smear where the red blood cells hardly touch. For a very thick smear, one might have to examine the platelets closer to the feathered edge.

1. Akwari AM, Ross DW, Stass SA. Spuriously elevated platelet counts due to microspherocytosis. Am J Clin Pathol. 1982;77(2):220–221.
2. Morton BD, Orringer EP, LaHart LA, Stass SA. Pappenheimer bodies: an additional cause for a spurious platelet count. Am J Clin Pathol. 1980;74(3):310–311.
3. Gulati G, Song J, Florea AD, Gong J. Purpose and criteria for blood smear scan, blood smear examination, and blood smear review. Ann Lab Med. 2013;33(1):1–7.

Mina L. Xu, MD
Director, Hematopathology
Associate Professor, Pathology and Laboratory Medicine
Yale School of Medicine
New Haven, Conn.
Member, CAP Hematology/Clinical Microscopy Committee