Correlation of second-trimester sonographic and biochemical markers.

Objectives: To investigate correlations between sonographic soft markers and biochemical markers (human chorionic gonadotrophin, alpha-fetoprotein, and estriol) for Down syndrome in the second trimester of pregnancy.

Methods: A total of 2183 women with apparently normal singleton fetuses who underwent second-trimester sonography (14-22 weeks) and maternal serum biochemical testing (triple test) were identified. Seven sonographic markers were recorded: nuchal fold thickness, humerus length, femur length, renal pyelectasis, hyperechoic bowel, echogenic intracardiac focus, and choroid plexus cysts.