MATERNAL SERUM SCREENING FOR FETAL DOWN-SYNDROME USING ALPHA-FETOPROTEIN, HUMAN CHORIONIC-GONADOTROPIN, AND UNCONJUGATED ESTRIOL IN ADOLESCENTS

Study Objective: To learn whether accuracy and false-positive rate of our maternal serum screening program for fetal Down syndrome differed in adolescents compared with adults. In addition, we studied the degre e to which overestimated gestational age accounted for screen-positive results and the rate at which amniocentesis was elected by patients i n different age groups. Design: Maternal serum screening using human c horionic gonadotropin (hCG), alpha-fetoprotein, unconjugated estriol a nd age was offered for fetal Down syndrome to all women between 15 and 20 weeks gestation who were less than or equal to 35 years of age at date of delivery. Women found to have a risk for fetal Down syndrome o f greater-than-or-equal-to 1:274 were considered screen-positive. If g estational age was confirmed by ultrasound, then genetic counseling an d amniocentesis were offered. Results: Of 10,627 women screened, 2,237 (21.1% of population screened) were between ages 12 and 19 years. Of these adolescents, 175 (7.5%) were screen positive. Of these 175, 114 (65.1%) were found-by ultrasonographic examination to have overestimat ed gestational age, and compared with adult women (ages 20-34 years); this was statistically significant (p < 0.003). Of the remaining 61 pa tients, 13 (21.3%) were lost to follow-up. The remaining 48 were offer ed genetic counseling and amniocentesis, of whom 38 (79.2%) elected to have amniocentesis. In the total population screened, four of seven D own syndrome cases were detected, one in a 19-year-old. In the three c ases not detected, one was in a 19-year-old and one was in a 22-year-o ld. Conclusions: Fetal Down syndrome screening may not be as sensitive in younger women as in older women, however, counseling and managemen t in adolescents need not differ from that of adults, Appropriate diag nostic procedures should be offered to all women at increased risk for fetal Down syndrome.