MEASUREMENT OF ADULT HEMOGLOBIN IN FETAL BLOOD-SAMPLES BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY AS PURITY CONTROL FOR THE PRENATAL-DIAGNOSIS OF CHROMOSOMAL-ABNORMALITIES

This study was aimed at testing if measurement of adult hemoglobin (Hb A) by ion exchange high-performance liquid chromatography could serve as a purity control of fetal blood samples. We studied 240 samples obt ained for karyotyping by cordocentesis under ultrasound guidance. Mean red cell volume (MCV), red cell distribution width (RDW) and HbA were measured on each sample. HbA was determined from 5 mul of blood in 8 min. From 18 to 30 weeks of gestation, HbA values in fetal blood do no t vary and are tightly clustered around 5.4% (SD:1.1%). After 30 weeks , HbA increases as the fetal to adult switch begins. Experimental cont aminations of fetal blood by maternal blood show that HbA variations a re more pronounced than MCV or RDW variations. A 5% contamination is r eadily detected. This approach is rapid, sensitive and reliable. Incid entally, it readily detects the presence of an abnormal hemoglobin.