Multiple marker screening and ultrasound can identify triploid fetuses in early gestation

Objective To combine a comprehensive ultrasound study with multiple marker screening to identify fetuses with triploidy. Study design A retrospective review of cases with prenatal diagnosis of fet al triploidy was carried out. Data were gathered from a combination of medical records, autopsy pathology , ultrasound and cytogenetic reports. Maternal serum a-fetoprotein (AFP), u nconjugated estriol and human chorionic gonadotropin (hCG) levels were corr elated with placental;and fetal phenotypes. Chromosomal heteromorphism from Q-banded preparations was used to determine the parental origin. Results Nine patients matched all inclusion criteria defined, and served as the population base for this study. There were five cases with a 69,XXX ka ryotype and four cases with a 69,XXY karyotype. Mean maternal age was 24.9 +/- 5.3 years (range 16-31 years). Mean gestational age at referral was 18. 3+/-2.6 weeks (range 15.3-22.9 weeks). Three cases were referred because of increased risk for both trisomy 21 and open neural tube defect. The other six cases were referred for increased risk for trisomy 18. The amniotic flu id AFP level was within the normal range for all but one case with elevated maternal serum AFP. Normal fetal growth or mild symmetric intrauterine gro wth restriction was found to coincide with both high levels of hCG and AFP, large cystic placenta and a paternal extra set of chromosomes. Severe asym metric intrauterine growth restriction with head circumference/abdominal ci rcumference ratio > 95% was found to coincide with low hCG level, non-cysti c small placenta and a maternal extra set of chromosomes. Conclusion The combination of second-trimester multiple marker screening an d ultrasound can identify triploid conceptuses. A correlation can be seen b etween the ultrasound findings, maternal serum level of AFP, unconjugated e striol and hCG, and parental origin of the extra set of chromosomes in trip loid conceptuses.