SCREENING FOR DOWNS-SYNDROME - EXPERIENCE IN AN INNER-CITY HEALTH DISTRICT

Objective To review the experience of Down's syndrome screening in an inner city health district. Design In this retrospective study the nam es of the women were obtained from the Regional Cytogenetic Laboratory and District Down's Syndrome Register. Antenatal notes of the mothers were studied. Maternal age during the affected pregnancy, screening t est performed if any, gestational age at booking and at screening, scr eening test results, and pregnancy outcome were reviewed. Setting An i nner city health district. Population Down's syndrome cases diagnosed prenatally and postnatally. Interventions None. Results Antenatal diag nosis of Down's syndrome was made in 15/45 women (33.3%); Edwards' syn drome was diagnosed antenatally in 2/5 women. Screening was not perfor med in eight women (17.8%) whose infants were affected by Down's Syndr ome; it was also not performed in one woman whose baby was affected by Edwards' syndrome due to late presentation to the antenatal clinic or loss of the blood sample. Nineteen women (42.2%) with a Down's syndro me pregnancy and two women with a Edwards' syndrome pregnancy had had a negative screening test. Three women had had a positive screening te st but declined amniocentesis. Among those who had a screening test, t he overall detection rate of screening was 48.6% (18/37) for Down's sy ndrome and 50% (2/4) for Edwards' syndrome. The detection rates in dif ferent ethnic groups did not show significant difference. Four women c hose not to have termination following diagnosis of Down's syndrome, g iving a total reduction rate of 21%. Conclusion Screening programmes f or Down's syndrome have not yet resulted in a substantial reduction in the number of affected babies. In addition to trials at developing sc reening programmes with better detection rates, efforts should be made to improve the provision of the screening service and the quality of antenatal care in general with emphasis on early presentation and opti mal understanding of the implications of the tests.