Biochemical screening for Down syndrome: patients' perception of risk

To determine the utility of the triple test in routine clinical practice and in addition to the document, the acceptability of a cut-off of 1:250 for invasive testing.

Retrospective analysis of data from screening and invasive testing for Down syndrome over a 5-year period in Hull Maternity Hospital. Computer-based records were accessed and individual data drawn from case notes were analyzed.

14827 (78%) of all patients opted for the triple test. A positive result (1:250 or greater) was found in 586 (4%). Fifteen percent of this group refused further testing with amniocentesis. 0.08% requested amniocentesis despite a negative triple test result. Of the screened pregnancies the triple test and selective invasive testing identified nine out of 15 (60%) of Down syndrome cases.

Sixty percent of Down syndrome pregnancies were identified with a 4% invasive testing rate. Fifteen percent of women who had a positive test did not agree with the cut-off of 1:250 and therefore declined invasive testing. Invasive procedure complication rates do not equate with patients' perception of Down syndrome.