Reference Values of Fetal Erythrocytes in Maternal Blood During Pregnancy Established Using Flow Cytometry

de Wit, Harry PhD
Nabbe, Karin C.A.M. PhD
Kooren, Jurgen A. PhD
Adriaansen, Henk J. MD, PhD
Roelandse-Koop, Elianne A. PhD
Schuitemaker, Joost H.N.
Hoffmann, Johannes J.M.L. PhD

¹Stichting KCL–Medical Center Leeuwarden, Leeuwarden, the Netherlands
²Rijnstate Hospital, Arnhem, the Netherlands
³Medial Laboratories, Hoofddorp, the Netherlands
⁴Gelre Hospitals, Apeldoorn, the Netherlands
⁵VU Medical Center, Amsterdam, the Netherlands
⁶IQ Products, Groningen, the Netherlands
⁷Abbott Diagnostics Division, Wiesbaden-Delkenheim, Germany

Address reprint requests to Dr Hoffmann: Abbott Diagnostics Division, Max-Planck-Ring 2, D-65205 Wiesbaden-Delkenheim, Germany.

American Journal of Clinical Pathology 136(4):p 631-636, October 01, 2011. | DOI: 10.1309/AJCPHL3VXY0VMLXL

The aim of our study was to assess the fetal RBC count in maternal blood during uncomplicated pregnancies from 26 weeks onward. We used a flow cytometric method specifically designed for use in a routine hematology analyzer.

Pregnant women were recruited through midwives. The participating laboratories used the FMH QuikQuant method (Trillium Diagnostics, Brewer, ME) in a CELL-DYN Sapphire hematology analyzer (Abbott Diagnostics, Santa Clara, CA). The method is based on a monoclonal antibody to hemoglobin F. Flow cytometric data were analyzed by 2 independent observers. The 95th percentile reference range was estimated according to Clinical and Laboratory Standards Institute guidelines.

A total of 236 samples were statistically analyzed. Gestational ages ranged from 21.6 to 41 weeks (mean, 32.0 weeks), and the fetal RBC count in maternal blood ranged from 0.00% to 0.50% (median, 0.025%).

The fetal RBC count in maternal blood shows no correlation with gestational age. The established reference range during normal pregnancy is less than 0.125%.