Nuchal translucency and the acceptance of invasive prenatal chromosomal diagnosis in women aged 35 and older

Objective: To investigate the effect of nuchal translucency screening on use of prenatal diagnosis for chromosomal abnormalities in women aged 35 and older. Methods: Two groups of women, referred to our center for prenatal karyotype diagnosis because of maternal age, were compared: one in 1995 and the other in 1999 after the introduction of nuchal translucency measurement. Each woman received nondirective genetic counseling, and for the 1999 group, nuchal translucency results were also discussed. Risks of transabdominal chorionic villi sampling (CVS) and amniocentesis, laboratory techniques, genetic results, and local experiences were discussed. Patient's decision to undergo prenatal diagnosis, acceptance of the nuchal translucency test (in the 1999 group), and the rate of chromosomal abnormalities diagnosed by transabdominal CVS and amniocentesis, were considered. Results: Two hundred twenty-one of 982 (22%) women in the 1995 group and 421 of 1386 (30%) in the 1999 group, after nondirective genetic counseling declined invasive diagnosis (P < .05). In the 1999 cohort, 1088 of 1089 (99.9%) women of appropriate gestational age had nuchal translucency measurement. Among women seen in 1995, 214 opted for transabdominal CVS (31%) and 476 (69%) for amniocentesis. Nineteen abnormal karyotypes were detected, six by trans-abdominal CVS and 13 (68.5%) by amniocentesis. In 1999, 266 women (29%) opted for transabdominal CVS and 650 (71%) for amniocentesis. Twenty abnormal karyotypes were detected, 13 (65%) by transabdominal CVS and seven (35%) by amniocentesis (P < .05). Conclusion: Knowledge of nuchal translucency could lead to a decrease in the demand for invasive diagnosis and to a more frequent diagnosis by first-trimester transabdominal CVS. (Obstet Gynecol 2001;97:916-20. (C) 2001 by The American College of Obstetricians and Gynecologists.).