title: Cell-free fetal deoxyribonucleic acid in maternal circulation as a marker of fetal-maternal hemorrhage in patients undergoing external cephalic version near term.
abstract: OBJECTIVE
  Our aim was to investigate whether external cephalic version performed near term increases the concentration of cell-free fetal deoxyribonucleic acid in maternal plasma.
  
  
  METHODS
  Forty-five patients who had singleton male fetuses and were undergoing external cephalic version at or beyond 36 weeks of gestation were recruited during a 20-month period. Maternal venous blood samples were taken before and within 10 minutes after external cephalic version. Deoxyribonucleic acid was extracted from the plasma samples. The amount of fetal deoxyribonucleic acid was quantified by means of the SRY gene on the Y chromosome as a fetal marker. The change in SRY gene concentration before and after external cephalic version was compared by paired sample t test.
  
  
  RESULTS
  There was a significant increase in the concentration of fetal deoxyribonucleic acid in maternal serum after external cephalic version (before, 296 +/- 209 copies per milliliter; after, 369 +/- 228 copies per milliliter; P =.014). This increase in the concentration of deoxyribonucleic acid was most profound among the nulliparous patients after a successful version and in the presence of a posterior placenta. The location of the placenta was found to be the most significant factor accounting for the change in the deoxyribonucleic acid concentration.
  
  
  CONCLUSIONS
  External cephalic version near term imposed a significant disturbance to the maternalplacental interface. Fetal deoxyribonucleic acid is a sensitive marker that is useful in the assessment of subclinical fetal-maternal hemorrhage.
authors.affiliation: Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Shatin, Hong Kong.
authors.forename: T K
authors.initials: TK
authors.lastname: Lau
authors.forename: K W
authors.initials: KW
authors.lastname: Lo
authors.forename: L Y
authors.initials: LY
authors.lastname: Chan
authors.forename: T Y
authors.initials: TY
authors.lastname: Leung
authors.forename: Y M
authors.initials: YM
authors.lastname: Lo
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood*; D004247:DNA / Q000097:blood*; D004268:DNA-Binding Proteins / Q000235:genetics; D005260:Female; D005331:Fetomaternal Transfusion / Q000097:blood*; D005333:Fetus / Q000378:metabolism*; D005865:Gestational Age; D006340:Heart Rate, Fetal; D006801:Humans; D008297:Male; D009687:Nuclear Proteins; D011247:Pregnancy; D011446:Prospective Studies; D051876:Sex-Determining Region Y Protein; D014157:Transcription Factors; D014710:Version, Fetal
chemical_list: D015415:Biomarkers; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; C497745:SRY protein, human; D051876:Sex-Determining Region Y Protein; D014157:Transcription Factors; D004247:DNA