Numerical and structural chromosomal anomalies in first trimester products of conception

Abstract

Objective: Multiple or complex chromosomal abnormalities are rare and are correlated with advanced maternal age and spontaneous abortion early in pregnancy. This study investigates the frequency of complex chromosomal abnormalities in products of conception in the first trimester of pregnancy.

Study design: 473 samples from first trimester aborted tissues were analyzed with conventional cytogenetic or molecular techniques. The average maternal age was 39 years (range 23-55). From each sample at least ten metaphases were analyzed using standard GTG banding.

Results: From 351 fetal origin cultured samples diagnosis was possible at 339 (97 %). Abnormal karyotypes were detected in 216 embryos (64 %) and a normal karyotype was detected in 123 (36 %). Non-complex chromosomal abnormalities were detected in 192 cases (89 %) with single trisomy 16 being the most frequent and complex abnormalities were identified in 24 cases (11 %). Polyploidies and monosomy 45,X occurred in 8 % each. Structural rearrangements and mosaicism were detected in 2 % and 3 %, respectively. Statistical analysis showed association between the week of gestation of single and complex chromosomal abnormalities (p = 0.04136).

Conclusions: Our results confirm that embryos with complex chromosomal abnormalities were more frequent among older women (>39 years old) and were aborted one week earlier than embryos with non-complex chromosomal abnormalities. Additionally, we have identified a higher number of complex chromosomal abnormalities (11 % vs 5-7 % in literature). Among complex chromosomal abnormalities, double trisomy was the most common finding, and the most frequent chromosomes involved were 21, X, and 15.

Keywords: Abnormalities; Complex chromosomal abnormalities; Conventional karyotype; Maternal age; Products of conception; Single chromosomal; Week of gestation.