(Arch Dis Child 1997;76:92-99)

The effectiveness and clinical utility of non-invasive prenatal diagnosis (NIPD) for fetal sex determination using cell-free fetal DNA (cffDNA) was assessed by undertaking a prospective national audit of UK testing. NIPD was performed using real-time polymerase chain reaction analysis of the DYS14 or SRY gene in cffDNA extracted from maternal plasma. All cases referred for fetal sex determination from 1 April 2006 to 31 March 2009 were ascertained from two laboratories offering the test. Fetal gender determined by NIPD was compared with that based on ultrasound, invasive test or phenotype at birth. Indication and rate of invasive testing was ascertained. In the first year, results were issued in 150/161 pregnancies tested. Of the 135 with outcome data, results were concordant in 130/135 [96.3% (95% CI 91.6-98.8%)]. Reporting criteria were changed and in the subsequent 511 pregnancies the concordancy rate increased to 401/403 [99.5% (95% CI 98.2-99.9%)]. Over the 3 years only 32.9% (174/528) underwent invasive testing. NIPD for fetal sex determination using cffDNA is highly accurate when performed in National Health Service laboratories if stringent reporting criteria are applied. Parents should be advised of the small risk of discordant results and possible need for repeat testing to resolve inconclusive results.

Objectives To improve the prenatal diagnosis of achondroplasia by constructing charts of fetal size, defining frequency of sonographic features and exploring the role of non-invasive molecular diagnosis based on cell-free fetal deoxyribonucleic acid (DNA) in maternal plasma. Methods

This workshop initiated a standardization process for extraction of cff DNA in maternal plasma. The highest yield was obtained by the QIAamp DSP Virus Kit, a result that will be evaluated in more detail in future studies.

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