An external quality assessment scheme for prenatal detection of rare chromosomal abnormalities

ObjectiveTo improve the accuracy of prenatal cytogenetic diagnosis by establishing an external quality assessment (EQA) scheme for rare, or subtle, structural chromosomal abnormalities.MethodTypical metaphase images of rare chromosomal abnormalities along with an anonymized clinical history were sent to 35 prenatal diagnosis laboratories. The laboratories were required to provide independent reports using current nomenclature. Evaluation of reports was based on established criteria for quality assessment of karyotype analysis.ResultsTotally 6 kinds of typical rare chromosomal abnormalities were collected. 35 laboratories were enrolled with a response rate of 94.29%. The overall analytical accuracy is 82.20%. This is comparable with our former EQA scheme using established lymphocyte cell lines with rare abnormal chromosome karyotypes (χ2 = 0.065, P = 0.799).ConclusionIntroduction of efficient EQA for prenatal genetic diagnosis is currently imperative, due to the limited performances of karyotype analysis of rare chromosomal abnormalities. Metaphase images could be used as a simple and effective material for EQA and to improve the quality of prenatal genetic diagnosis.

► Prenatal detection of rare or subtle chromosomal abnormalities is difficult.
► Metaphase images could be used as a simple and effective material for EQA.
► It will improve the integrated capability of prenatal cytogenetic diagnosis.