Background: To determine the incidence of chromosome abnormalities (CAs) in prenatal cytogenetic diagnosis, to describe and compare indications in Italian and migrant women, and to assess the level of compliance with published national guidelines.
Methods: A retrospective analysis of 7806 amniotic fluid samples (AFS) and 228 chorionic villi samples (CVS) was conducted.
Results: Advanced maternal age was the most common indication. CAs incidence was 3.1 per 100 AFS, and 12.6 per 100 CVS. Only parental chromosome rearrangement and ultrasound abnormalities were significantly associated with CA occurrence (RR= 20.15 95%CI: 11.96-33.96; RR= 4.33; 95%CI: 2.95-6.36, respectively). Both in amniocentesis and in chorionic villi sampling CA incidence was significantly higher when performed according to the national guidelines, than for other reasons. Incidence data for trisomy 21, trisomy 18 and inversions were significantly higher than those reported in a previous Italian report.
Conclusions: Increased maternal age may explain, at least in part, the increase by time of CAs, although an excess was shown in our population independently from it. Our results show that advanced maternal age may not be sufficient as a single criterion for prenatal diagnosis, and suggesting a future revision of national clinical indications is suggested.