Pregnant women should be counselled and fully informed before undergoing examination for soft markers on routine mid-trimester scans, a study from Toronto has concluded. 'Mid-trimester ultrasound examination is a form of screening and all women agreeing to it should be counselled before proceeding. All clinical screening can potentially cause harm as well as benefit. In the case of soft marker screening the harm includes false-positive results and screening women who if asked would have declined. In my opinion, women who do not want Down's syndrome screening should not have soft markers assessed without their informed consent.'