Prenatal diagnosis and genetic screening : community and service implications / a report of the Royal College of Physicians.

  • Royal College of Physicians of London.
Date:
1989
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Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Prenatal diagnosis and genetic screening : community and service implications / a report of the Royal College of Physicians. Source: Wellcome Collection.

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    CONGENITAL MALFORMATIONS Serological testing shows exposure to Rubella etc Obstetric procedure CVS Fetal blood sampling Maternal serum AFP raised Routine anomaly scaiv. abnormality suspected Family history of malformation Maternal diabetes CHROMOSOMAL DISORDERS either Amniocentesis N Level 3 ultrasound for direct visualisation: malformation seen and may suggest CA'S or fetal blood — sampling Previous abnormality Familial chromosomal rearrangement Maternal age ms - AFP - unconjugated oestriol - HCG INHERITED DISEASES Family history Population screening* Integrated result suggests > 0.5 -1.1 risk ~\ ' CVS j Ultrasound carrier testing shows couple at risk l \ 1111 k 1 ULt 11 ILolo Fetal blood sampling y (according to disorder) CVS or amniocentesis Laboratory investigation -► Viral DNA -► Fetal antibodies Amniotic fluid Alphafetoprotein and other tests -*■ Karyotyping Karyotyping Biochemistry DNA studies Sometimes karyo typing *At present limited to selected populations, screened for haemoglobin disorders or Tay-Sachs disease Fig 6. Summary of present strategies for screening and prenatal diagnosis. Primary screening iv Prenatal diagnoses should, whenever possible, be confirmed in aborted fetuses, and in babies born following diagnosis. The services of an expert in fetal pathology are essential. v Results should be subjected to regular audit, with particular emphasis on false positives and false negatives. National and regional monitoring should be established. vi The genetic, obstetric and laboratory aspects of prenatal diagnosis are closely related and optimal results require close collaboration. Ideally, the obstetric scanning and sampling procedures, counselling, and laboratory analysis should be practised side-by-side in the same institution. vii W omen with a continuing pregnancy in which a fetal abnormality has been diagnosed, require expert support from the neonatologist and neonatal surgeon. 2.5 In addition to being safe, simple and cheap, screening methods should be reliable. They should have a high detection rate (a high proportion of affected individuals should yield a positive result) and a low false-positive rate (few un affected individuals should yield a positive result) [4]. Whenever possible, screening should be carried out before pregnancy. Table 5 shows that many present methods fall short in one or more of these requirements.