Effect of First-trimester Ultrasound Examination for Chromosomal Aberrations in Women Undergoing Amniocentesis

Abstract

Objective: The purpose of this study was to assess the effect of first-trimester ultrasound examination for chromosomal aberrations in women who underwent amniocentesis.
Methods: To evaluate trends in the indications of amniocentesis and the number of chromosomal aberrations, we reviewed all amniotic fluid samples from genetic amniocentesis processed by the Tama-Nagayama Hospital of Nippon Medical School from 1991 through 2005. The referral indications included first-trimester abnormal ultrasound finding.
Results: A total of 1,054 women underwent genetic aminiocentesis in the first- to early second-trimester, and 1,063 amniotic samples were processed. The overall rate of chromosomal aberrations was 3.3% (35 of 1,063 samples), and the rate of aberrations remained unchanged during the study period. The number of cases with abnormal ultrasound finding increased from 5 (1.1%) in the first 5-year period to 46 (19.4%) in the last 5-year period (p<0.01). In contrast, the number of amniotic fluid samples per year tended to decline during the study period.
Conclusion: First-trimester ultrasound examination had a significant effect on our amniocentesis cases. The application of first-trimester ultrasound examination may be associated with a lower rate of invasive genetic testing.