Counseling in medical genetics / Sheldon Reed.

  • Sheldon Clark Reed
Date:
[1980]
Catalogue details

Licence: Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)

Credit: Counseling in medical genetics / Sheldon Reed. Source: Wellcome Collection.

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    Amniocentesis and Prenatal Diagnosis Amniocentesis could be carried out on every woman who is in the early stages of pregnancy. This would be desirable on humanistic considerations, but is not likely to happen for several reasons, the most important one being that many women would refuse the offer. Another important reason which is likely to prevent large scale utilization of amniocentesis, is that the benefit-cost ratio will be unacceptable for some time to come. But for special cases it is indispensable. Amniocentesis evolved as a part of the management of Rh disease. The idea was to sample the amniotic fluid when the fetus was thought to have a high bili¬ rubin level as a result of erythroblastosis. The amniotic fluid could be tested colorimetrically and appropriate decisions made about the fetus. The technique was soon adapted to the more exciting use in prenatal genetic studies, as suggested by Fuchs and Philip [1963] (see Figure 7). Safety One of the reasons amniocentesis has gained such rapid and widespread accept¬ ance is that it is almost completely safe. Moderate amounts of amniotic fluid (20—50 ml) can be removed at 16—18 weeks after the last menstrual period with little danger to either the mother or the fetus. There is now a considerable body of well documented literature concerning the safety aspects of prenatal diagnosis. A study by Munk-Andersen et al [1977] with carefully matched controls found no significant differences in Apgar score, birth weight, body length, duration of pregnancy, placenta condition, or malformation of the children born subsequent to amniocentesis. Two spontaneous abortions occurred, but they could not be definitely connected with the amniocentesis procedure. There was a decrease in bloody taps in the cases where ultrasound was carried out compared with those without it. An earlier study of 6,121 prenatal diagnoses carried out at 46 centers in Europe was reported by Galjaard [1976]. The percentage of spontaneous abortions following early amniocentesis (1.4%) did not seem to exceed the normal rate of spontaneous abortion in that period of pregnancy. See also Crandall et al [1979]. Monitoring for Many Diseases This latter study showed that the majority of the prenatal monitoring cases were carried out because of the risk of chromosomal aberration. Most of the remaining cases (2,708) represented searches for open neural tube defects, while 47
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