Background: When abnormalities are found during the anatomy scan most patients are offered amniocentesis and conventional karyotyping, using Giemsa (G)-banding of metaphase chromosomes to detect aneuploidies and large structural changes in the prenatal diagnosis. The use of fluorescent in situ hybridization (FISH) reduces the time to obtain a result because culture is not necessary, but can only detect a limited number of prespecified targets. Small studies have shown that array comparative genomic hybridization (aCGH) can detect all unbalanced chromosomal abnormalities as well as smaller deletions and duplications that cannot be detected with routine cytogenetic analysis. Should aCGH screening be used instead of karyotyping to diagnose prenatal chromosomal abnormalities in pregnant patients with abnormal ultrasound?
Methods: An exhaustive search of available medical literature from the past 5 years was conducted using Medline-OVID, CINAHL, Web of Science. Key words included: comparative genomic hybridization, pregnancy, abnormal ultrasound, prenatal ultrasound and ultrasound. Relevant articles were assessed for quality using GRADE.
Results: Two studies met inclusion criteria and were used in this review. The first is a large prospective, comparison to gold standard (karyotyping). This study compared prenatal diagnostic samples, and found microarray (aCGH) was equivalent to standard karyotype analysis for common aneuploidies and found additional clinically relevant information when patients had abnormal ultrasounds. The second study was a prospective study of over 5000 pregnancies and again additional clinical significant findings were found using aCGH.
Conclusion: Array comparative genomic hybridization should be considered for all patients who wish to undergo invasive prenatal screening and should be offered to all patients with abnormal prenatal ultrasounds. Adequate genetic counseling should be provided by a trained professional in all cases. A cost analysis should be done comparing tests.
Keywords: Array comparative genomic hybridization, pregnancy, abnormal ultrasound, prenatal diagnosis
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