Charge flow separation: Quantification of nucleated red blood cells in maternal blood during pregnancy

Stephen S. Wachtel, David Sammons*, Garland Twitty, Joe Utermohlen, Elizabeth Tolley, Owen Phillips, Lee P. Shulman

*Corresponding author for this work

Research output: Contribution to journalArticle

42 Scopus citations


We set out to ascertain the numbers of fetal cells that enter the maternal blood stream during pregnancy. Samples of 15-16 ml of whole blood were collected from 225 women - mostly 10-18 weeks pregnant - and then processed by charge flow separation, a novel method based on free flow electrophoresis in a buffer counterflow gradient. After their recovery in four different separation instruments, nucleated red blood cells (NRBC) were enumerated histologically. In some cases fetal NRBC were identified and enumerated by fluorescence in situ hybridization with probes for the X and Y chromosomes and fetal haemoglobin mRNA. Recoveries were consistent among the four separation instruments: the median numbers of NRBC obtained were 4190, 1590, 2805 and 3860. Our data show that approximately 30 per cent of those cells were fetal. Thus, recent reports on the separation of fetal NRBC by other methods, give underestimates of their frequency in maternal blood.

Original languageEnglish (US)
Pages (from-to)455-463
Number of pages9
JournalPrenatal Diagnosis
Issue number5
StatePublished - May 1998


  • Charge flow separation
  • Fetal cells in maternal blood
  • Prenatal diagnosis

ASJC Scopus subject areas

  • Obstetrics and Gynecology
  • Genetics(clinical)

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