Overview of Chromosome Abnormalities in First Trimester Miscarriages: A Series of 1,011 Consecutive Chorionic Villi Sample Karyotypes

TLDR

The study aimed to determine the types and frequencies of chromosomal abnormalities in first‑trimester miscarriages using a high‑success, contamination‑free diagnostic approach. Researchers cultured 1,119 chorionic villi samples—short‑term for all and long‑term for 603—to generate karyotypes and quantify abnormality frequencies, placental mosaicisms, and their associations with maternal age and gestational week. Abnormal karyotypes were found in 70.3% of cases, with single autosomal trisomy (64.6% of abnormalities) most common, followed by triploidy (13.1%) and monosomy X (10.4%); rearrangements, combined abnormalities, and placental mosaicism occurred in 5.2%, 8.9%, and 3.5% respectively, and trisomy patterns varied with maternal age and survival.

Abstract

In order to contribute to the knowledge of type and frequency of chromosome abnormalities in early pregnancy losses, we analyzed the cytogenetic results from a large series of first trimester miscarriages, using a diagnostic approach with a high success rate and no maternal contamination. A total of 1,119 consecutive chorionic villi samples were obtained before evacuation, and karyotypes were prepared after short-term culture (STC). In 603 samples, a long-term culture (LTC) was also performed. The overall and individual frequencies of the different types of chromosome abnormalities were established, including placental mosaicisms, and their relationship with maternal age and gestational weeks was assessed. An abnormal karyotype was detected in 70.3% of the samples. Single autosomal trisomy was the most frequent abnormality (64.6% of the abnormal cases), followed by triploidy (13.1%) and monosomy X (10.4%). Chromosome rearrangements were found in 5.2%, combined abnormalities in 8.9%, and placental mosaicism in 3.5% of the cases with STC and LTC performed. Individual trisomies behaved differently with respect to maternal age and intrauterine survival. Due to the combination of STC and LTC, our study offers reliable information on the incidence and type of chromosome abnormalities and placental mosaicism in miscarriages and contributes to define the cytogenetic implication in their etiology.