Technical aspects and diagnostic problems of direct chromosome analysis using chorionic villus sampling in the first...

Area of Science:

• Prenatal Diagnosis
• Cytogenetics
• Fetal Medicine

Background:

• First-trimester genetic screening is crucial for early detection of fetal aneuploidies.
• Transcervical chorionic villus sampling (CVS) offers an alternative route for obtaining fetal genetic material.
• Direct chromosome analysis of villi provides rapid karyotyping results.

Purpose of the Study:

• To evaluate the efficacy and diagnostic accuracy of direct chromosome analysis on first-trimester transcervical CVS samples.
• To determine the rate of diagnostic failure and chromosomal abnormalities detected.
• To assess the reliability of placental karyotypes compared to fetal tissues.

Main Methods:

• Described 18 months of experience with direct chromosome analysis of villi obtained via trans-cervical catheter insertion.
• Analyzed 325 biopsy samples for karyotyping.
• Performed cytogenetic control on fetal tissues after voluntary abortion for cases with abnormal karyotypes.

Main Results:

• A total of 325 samples were analyzed with a diagnostic failure rate of 1.8% (6 cases).
• Abnormal karyotypes were detected in 3.8% of cases (12 cases).
• Two cases showed karyotype discrepancies between placental villi and fetal tissues, including three mosaic findings initially.

Conclusions:

• Direct chromosome analysis of first-trimester transcervical CVS is a reliable method for prenatal diagnosis.
• The technique demonstrates a low diagnostic failure rate and effectively identifies chromosomal abnormalities.
• Careful interpretation is needed for mosaic findings and potential placental-fetal karyotype discrepancies.