Chorionic Villi Sampling Amongst Early and Late Gestational Age: Does Timing Affect Yield and Outcomes?

Background: Chorionic villus sampling (CVS) is a diagnostic procedure that can be performed between 10 weeks 0 days and 13 weeks 6 days to detect genetic abnormalities, however a majority of providers opt to perform CVS after 11 weeks. This study evaluated the feasibility of CVS performed at varying gestational ages, comparing chorionic villi yield and procedural outcomes among early, typical, and late procedures. Methods: This multicenter retrospective study included patients with CVS categorized as early (10w0d–10w6d), typical (11w0d–13w6d), and late CVS (≥14w0d). The primary outcome was median CV weight. Secondary outcomes included need for culture, time to microarray results, and a sub-analysis of abnormal CMA results, obstetric and neonatal outcomes. Results: Of 719 patients, 8.1% underwent early, 83.2% typical, and 8.8% late CVS. The early cohort had lower BMI. Early CVS was most frequently performed transvaginally and for indication of prior affected pregnancy, and less likely for abnormal genetic screening or ultrasound findings. Median villi weight did not differ significantly, and 89% of all procedures yielded adequate tissue, defined as ≥5 mg. Time to microarray result was shortest in the typical group. There were no significant differences in other secondary outcomes of need for culture, number of passes, or procedure-related complication rates. There was no case of limb anomalies. Conclusions: CVS performed before 11 weeks and after 14 weeks demonstrated comparable microarray outcomes and demonstrate the technical feasibility and diagnostic adequacy of CVS performed outside the typical gestational window. The results also support the availability of early CVS for cytogenetic testing in early pregnancy loss where management may not allow for direct tissue testing. Prospective studies are warranted to validate these results and refine recommendations for optimal timing of CV