Influence of formal soft marker detection on amniocentesis uptake following mid-trimester screening of trisomy 21

The absence of second trimester ultrasound soft markers associated with trisomy 21 reduces the risk of having the condition. We evaluated whether women with 'high risk' AFP HCG results are influenced in their request for amniocentesis when soft-marker testing is reported formally. All women with an increased trisomy 21 risk (> 1:220) referred for counselling between June 1998 and June 1999 (group 1) and February 2001 and February 2002 (group 2). Group 1 underwent a level 2 anomaly scan and their risk was not altered formally by the presence or absence of soft markers. Group 2 underwent a level 2 anomaly scan with the addition of examination for soft markers (echogenic intracardiac foci, nuchal oedema, pyelectasis, short femur and echogenic bowel). In the absence of anomalies and soft markers, the trisomy 21 risk was halved and the woman informed of the adjusted risk prior to undergoing or declining amniocentesis.