Room for improvement? Detecting autosomal trisomies without serum screening

Abstract

To assess the efficacy of the prenatal screening and diagnostic programme for the detection of the common autosomal trisomies in the North West Thames region prior to the introduction of serum screening. A retrospective study based on reports made to the North West Thames Regional Health Authority Congenital Malformation Register. 235 pregnancies of women delivered in units in the North West Thames region over a two-year period (1990-91) whose babies or fetuses were diagnosed as having Down, Edwards or Patau syndrome. 33% of Down syndrome, 68% of Edwards syndrome and 52% of Patau syndrome were diagnosed prenatally (before 28 weeks) in the region without the use of serum screening. Using maternal age and routine ultrasound as screening methods, units in the region are prenatally diagnosing significantly fewer Down syndrome babies than are those in authorities using serum screening. The use of maternal age and ultrasound screening is more effective for the antenatal detection of the other autosomal trisomies than it is for the detection of Down syndrome. It is not yet clear to what extent serum screening might be expected to increase the detection rate for these conditions.