Cordocentesis for Rapid Cytogenetic Diagnosis: A Retrospective Cohort Study of 160 Cases Cytogenetic Diagnosis by Cordocentesis: Retrospective Analysis

Abstract

Objective: It is aimed to evaluate the concordance between quantitative fluorescent polymerase chain reaction (QF-PCR) and conventional cytogenetic analysis in pregnancies undergoing cordocentesis, and to assess indications, diagnostic yield, turnaround time, and the association between maternal age and chromosomal abnormalities. Methods: This retrospective cohort study included 160 pregnancies that underwent cordocen-tesis between August 2019 and July 2022 in the Department of Perinatology of a tertiary referral center. Maternal age, indication for procedure, gestational age, QF-PCR results, conventional karyotype findings, and laboratory reporting times were analyzed. Procedure indications were categorized according to ultrasonographic findings, screening test results, and previous prenatal invasive genetic test results. Results: The most common indication was major ultrasonographic abnormalities (53.1%). QF-PCR demonstrated 100% concordance with cytogenetic analysis for trisomy 21 and trisomy 18. However, among cases reported as normal by QF-PCR, structural chromosomal abnormalities (4.5%) and rare numerical anomalies, including mosaic trisomy 8 and trisomy 9, were detected on conventional karyotyping. The highest rate of abnormal karyotype was observed in the major ultrasonographic findings group (12.9%). Mean turnaround time for conventional cytogenetic results was 11.7±3.5 days. Advanced maternal age was strongly associated with trisomy 21 and trisomy 18. Conclusions: QF-PCR provides a rapid and reliable preliminary assessment for common aneuploidies in cordocentesis cases; however, conventional cytogenetic analysis remains essential for definitive diagnosis due to its ability to detect structural and rare chromosomal abnormalities. In late-gestation referrals, the relatively short reporting time of fetal blood culture supports cordocentesis as a valuable diagnostic option when timely clinical decision-making is required.