A woman with uterine fibroids has an increased risk of receiving a false-positive result for a sub-chromosomal aberration on prenatal cell-free DNA testing, Australian researchers have found.

Such a result is more likely with growths that are large or numerous, according to findings from a study the authors say is the first comprehensive assessment of how fibroids affect the accuracy of non-invasive prenatal testing (NIPT). 

Patients can be reassured, however, that fibroids do not appear to interfere with detection of fetal aneuploidies, says the team, who are specialists in obstetric and gynaecological ultrasound.

Usually, about 90% of the cell-free DNA analysed in the test is maternal and about 10% comes from placental syncytiotrophoblast, say the authors, led by Dr Fergus Scott from Sydney Ultrasound for Women.