Nuchal translucency and first trimester risk assessment: a systematic review.

First-trimester risk assessment for fetal aneuploidy using nuchal translucency (NT) measurement is rapidly gaining popularity in the United States. In combination with maternal serum markers in the first trimester, the screening performance is exceptionally good, with detection rates of more than 80% at a screen positive rate of 5%. Recently, the method has been validated for screening for Down syndrome and other aneuploidies in multicenter trials in the United States and elsewhere. Compliance with established criteria for measurement of the NT is essential to achieve uniform reliability and high screening test sensitivity. There is an international consensus about the importance of specific training in the NT examination, conformity to standards of NT measurement, and regular audit for quality assurance. In the United States, the Nuchal Translucency Quality Review program has been developed to administer credentialing and quality review for registered practitioners. The Nuchal Translucency Quality Review credentials signify the proficiency of the sonographer or sonologist in NT measurement and participation in a regular quality assurance audit. We encourage accreditation of clinical sites offering first-trimester risk assessment to ensure the highest quality care.