Chorionic Villous Testing Versus Amniocentesis After Abnormal Noninvasive Prenatal Testing

Area of Science:

• Prenatal diagnostics
• Genetics
• Maternal-fetal medicine

Background:

• Cell-free DNA (cfDNA) screening is a common method for prenatal aneuploidy detection.
• High-risk cfDNA results for trisomy 13 often necessitate invasive diagnostic testing.
• Confined placental mosaicism (CPM) can complicate interpretation of cfDNA screening and invasive testing.

Purpose of the Study:

• To evaluate the optimal invasive diagnostic strategy following a high-risk cfDNA result for trisomy 13.
• To outline further investigations based on specific cfDNA screening results in cases of unaffected fetuses.

Main Methods:

• Review of current literature and clinical guidelines regarding cfDNA screening and invasive testing.
• Analysis of diagnostic yield and risks associated with amniocentesis and chorionic villus sampling (CVS).
• Consideration of additional genetic tests based on cfDNA findings.

Main Results:

• Amniocentesis is recommended over CVS for high-risk trisomy 13 due to high rates of confined placental mosaicism.
• For non-trisomy 13 cfDNA findings in unaffected fetuses, targeted evaluations are suggested.
• These include maternal karyotyping for monosomy X, uniparental disomy testing, serial growth scans for trisomy 16, and maternal workup for malignancy.

Conclusions:

• Amniocentesis is the preferred invasive test after cfDNA screening indicates high risk for trisomy 13, especially with normal first-trimester ultrasound.
• Tailored follow-up testing is crucial for managing diverse cfDNA screening results to ensure accurate prenatal diagnosis and management.