Sonographic Findings in Trisomy 9

Objective. The purpose of this study was to identify the most common prenatal sonographic findings in fetuses with complete trisomy 9. Methods. A retrospective review of all cases of trisomy 9 at 5 participating institutions over a 15-year interval was conducted. Indications for referral and sonographic findings in each case were reviewed to identify characteristic fetal structural anomalies. Results. Six cases of trisomy 9 are presented. Most patients were referred for abnormal sonographic findings on screening examinations (66%) or advanced maternal age (33%). Fetal heart defects and central nervous system malformations were the most frequent sonographic anomalies seen. Conclusions. Sonographic findings in trisomy 9 are similar to those found in other autosomal trisomies. Because trisomy 9 is uniformly lethal and is not included as part of the standard prenatal aneuploidy screening by fluorescence in situ hybridization analysis, clinicians should be cautious in counseling patients with structurally abnormal fetuses until the full karyotype is available.