CHORIONIC VILLUS SAMPLING AND AMNIOCENTESIS ๐ŸŽ—

"Prenatal diagnosis has transformed the practice of medical genetics.” - Dr. Aubrey Milunsky

๐Ÿงฌ Chorionic villus sampling (CVS) and amniocentesis remain two epitomic invasive procedures in prenatal genetic diagnosis. Unlike screening approaches such as ultrasound and cell-free DNA testing, they provide diagnostic fetal-derived material for chromosomal and molecular analysis.

     ๐Ÿ”น Chorionic villus sampling (CVS) is generally performed at 10–13 weeks of gestation. Chorionic villi are obtained from the placenta through a transabdominal or transcervical approach under ultrasound guidance. The sample can support karyotyping, chromosomal microarray, and targeted molecular testing, enabling relatively early diagnosis of conditions such as trisomy 21, 18 and 13, as well as selected single-gene disorders.

      ๐Ÿ”น Amniocentesis is typically performed from 15 weeks onward. A small volume of amniotic fluid is collected transabdominally under ultrasound guidance. Fetal cells can be analyzed using karyotyping, chromosomal microarray and targeted molecular testing. In selected clinical circumstances, amniotic fluid can also support investigations for fetal infection and other conditions.

     ๐Ÿ”น CVS provides earlier diagnostic information but samples placental tissue. Therefore, confined placental mosaicism can occasionally complicate interpretation and may require follow-up amniocentesis. Amniocentesis samples fetal cells present in amniotic fluid and may therefore provide a more direct representation of the fetal chromosome complement.

      ➡️ Both procedures are invasive and carry a small risk of pregnancy loss and other complications. Importantly, contemporary evidence suggests that the procedure-related risk of miscarriage is lower than historically quoted and depends on baseline pregnancy risk, gestational age, technique and operator experience. Modern prenatal diagnosis increasingly integrates karyotyping, chromosomal microarray and targeted genomic testing; vital components of diagnostic evaluation in appropriate cases.

⚠️ In an Oystershell CVS and amniocentesis are complementary rather than competing technologies. CVS offers the advantage of earlier diagnosis, while amniocentesis can provide highly informative fetal genetic material later in pregnancy. Appropriate test selection, laboratory interpretation, informed consent and expert genetic counseling remain essential for interpreting genomic findings into meaningful clinical decisions.

Abubakar Abubakar ✍

• Salomon LJ, et al. Ultrasound Obstet Gynecol. 2019;54(4):442-451.

• Akolekar R, et al. Obstet Gynecol. 2015;45(1):16-26.

• ACOG Committee on Genetics & Society for Maternal-Fetal Medicine. Committee Opinion No. 682.

#PrenatalDiagnosis #GeneticCounseling #CVS #Amniocentesis #PrenatalGenetics #GenomicMedicine #HumanGenetics #PrecisionMedicine #MedicalGenetics #CRISPR #NGS #PGT #IVF #ART ⚕️

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