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Fetal macrocytosis in association with chromosomal abnormalities
N M Fisk1, Y Tannirandorn, J Santolaya
1Department of Hematology, Royal Postgraduate Medical School, London, United Kingdom.
Obstetrics and Gynecology
|October 1, 1989
Summary
Elevated fetal mean red cell volume (MCV) can indicate chromosomal abnormalities like triploidy or monosomy X. This finding suggests karyotyping for fetuses with high MCV during prenatal blood sampling.
Area of Science:
- Perinatal Medicine
- Fetal Diagnostics
- Genetics
Background:
- Mean red cell volume (MCV) is a standard hematological parameter.
- Fetal MCV changes with gestational age and can be affected by various conditions.
Purpose of the Study:
- To establish a normal range for fetal MCV.
- To investigate the association between elevated fetal MCV and chromosomal abnormalities.
- To assess the diagnostic utility of fetal MCV in predicting abnormal karyotypes.
Main Methods:
- Determined MCV in 264 fetuses (15-41 weeks gestation).
- Excluded anemic, hypoxic, and chromosomally abnormal fetuses for normal range construction.
- Analyzed MCV in fetuses with known chromosomal abnormalities and gross anomalies.
Main Results:
- Fetal MCV decreased with gestation (r = -0.64, P < .001).
- Elevated MCV was observed in fetuses with triploidy, monosomy X, trisomies 18/21, and gross anomalies.
- Macrocytosis showed 71% sensitivity and 95% specificity for abnormal karyotypes in the second trimester.
Conclusions:
- Fetal MCV is a potentially useful indicator during prenatal diagnosis.
- An elevated MCV in nonanemic fetuses may warrant consideration for karyotyping.
- MCV elevation correlates with nucleated red cells and reticulocytes in chromosomally abnormal fetuses.