Application of the 'Apt test' in prenatal diagnosis to evaluate the fetal origin of blood obtained by cordocentesis: results of 30 pregnancies

Prenat Diagn. 1997 Sep;17(9):879-82. doi: 10.1002/(sici)1097-0223(199709)17:9<879::aid-pd152>3.0.co;2-p.

Abstract

This study aimed to set up a practical lab-side approach to discriminate fetal from maternal blood in samples obtained by cordocentesis. To determine the fetal origin of the blood, a modified Apt test was applied to 30 cases of prenatal diagnosis. A change of colour of the fetal and adult blood during the procedure was the hallmark to assess fetal origin. At the end of 60 s of the test, fetal blood yielded a pink colour whereas adult blood was dark green-brown. The test was repeated in mixtures of fetal and adult blood. The results suggest that the modified Apt test is a practical, quick, inexpensive, and efficient test to determine the origin of blood samples obtained by cordocentesis. However, it should be kept in mind that samples containing a mixture of both fetal and adult blood could also yield a fetal blood reaction. When maternal contamination is suspected, we propose that at least 30 metaphases from different slides should be counted. This could yield fetal as well as maternal chromosomes.

MeSH terms

  • Cordocentesis / methods*
  • Female
  • Fetal Blood / chemistry*
  • Fetal Blood / cytology
  • Hemoglobins / analysis*
  • Humans
  • Karyotyping
  • Metaphase
  • Pigmentation
  • Pregnancy / blood*
  • Pregnancy Outcome*
  • Prenatal Diagnosis / methods*
  • Umbilical Cord / chemistry

Substances

  • Hemoglobins