Method of risk assessment affects acceptance rate of amniocentesis

Risk assessment for aneuploidy is an integral part of modern obstetrics. However, patients might choose or reject an amniocentesis, based, not on the risk, but on the screening method used. We examined records of patients referred for evaluation of aneuploidy risk from January 1999 to December 2000. Patients found to have a risk above 1/250 were offered amniocentesis. Out of 555 patients found at risk, 336 (60.5%) accepted. Acceptance rate varied depending on risk factor identified: advanced maternal age 178/290 (61.4%), abnormal serum screening 107/198 (54%), sonographic markers 35/48 (72.9%) or a previous child aneuploidy 16/19 (84.2%). The risk assessment method used influences significantly the amniocentesis acceptance rate and may affect sensitivity of testing.