Abstract
BackgroundCytogenetic evaluation of products of conception (POC) for chromosomal abnormalities is central to determining the cause of pregnancy loss. We compared the test success rates in various specimen types and the frequencies of chromosomal abnormalities detected by G-banding analysis with those found by Oligo-SNP chromosomal microarray analysis (CMA). We evaluated the benefit of CMA testing in cases of failed culture growth.MethodsConventional cytogenetic results of 5457 consecutive POC specimens were reviewed and categorized as placental villi, fetal parts, and unspecified POC tissue. The CMA was performed on 268 cases. Of those, 32 cases had concurrent G-banding results. The remaining 236 cases included 107 cases with culture failure and 129 cases evaluated by CMA alone.ResultsThe overall POC culture success rate was 75%, with the lowest for fetal parts (37.4%) and the highest for placental villi (81%). The abnormality rate was 58% for placental villi, but only 25% for fetal parts. Of the abnormalities detected, the most common were aneuploidies, including trisomy 16, triploidy, monosomy X, trisomy 22, trisomy 21 and trisomy 15, while the least encountered aneuploidies were trisomy 1, trisomy 19 and monosomies (except monosomy 21). Overall, POC specimens studied by CMA were successful in 89.6% of cases and yielded a 44.6% abnormality rate.ConclusionsPlacental villi yielded higher rates of culture success and a higher percentage of abnormal karyotypes than did other specimen types. The Oligo-SNP CMA method has demonstrated a viable alternative to the G-banding method in view of its advantages in detection of submicroscopic genomic aberrations, shorter turnaround time due to elimination of time required for culture and a higher test success rate.
Highlights
Cytogenetic evaluation of products of conception (POC) for chromosomal abnormalities is central to determining the cause of pregnancy loss
A total of 5457 consecutive POC specimens were categorized as placental villi, fetal parts, and unspecified POC tissue, cultured, harvested and analyzed by conventional cytogenetic analysis method as described elsewhere
In the Oligo-SNP chromosomal microarray analysis (CMA) study series, the 32 cases analyzed by both G-banding and the array method demonstrated 81% (26/32) concordance, confirming all unbalanced abnormalities and detecting additional abnormalities in 5 cases not identified by the G-banding method, which included one case with a cryptic unbalanced (1;10) translocation and 4 cases with a VOUS result
Summary
Cytogenetic evaluation of products of conception (POC) for chromosomal abnormalities is central to determining the cause of pregnancy loss. We compared the test success rates in various specimen types and the frequencies of chromosomal abnormalities detected by G-banding analysis with those found by Oligo-SNP chromosomal microarray analysis (CMA). We evaluated the benefit of CMA testing in cases of failed culture growth. Spontaneous pregnancy loss is a common clinical occurrence. Among women who know they are pregnant, the miscarriage rate is 15-20% [1,2]. Aneuploidy and unbalanced chromosomal abnormalities account for 50-60% of fetal loss during this period [3,4,5,6]. Cytogenetic evaluation of the products of conception (POC) is central in determining the cause of
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