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Amniocentesis or chorionic villus sampling for prenatal genetic testing: a decision analysis.
1Department of Medicine, University of Illinois, Chicago 60680.
Journal of Clinical Epidemiology
|January 1, 1991
Summary
For pregnant women aged 35, amniocentesis is generally preferred over chorionic villus sampling (CVS) and no prenatal testing. However, CVS may be chosen if a first-trimester abortion is strongly preferred or anxiety about waiting for results is high.
Area of Science:
- Medical Decision Making
- Prenatal Diagnosis
- Obstetrics & Gynecology
Background:
- Women aged 35 and older have an increased risk of chromosomal abnormalities in their fetus.
- Prenatal diagnostic procedures like amniocentesis and chorionic villus sampling (CVS) offer options for assessing fetal genetic health.
- Choosing between these tests involves complex considerations of risks, benefits, and patient preferences.
Purpose of the Study:
- To analyze and compare the decision-making strategies for prenatal testing in women aged 35.
- To evaluate the expected utility of amniocentesis, chorionic villus sampling (CVS), and no prenatal testing.
- To identify factors influencing the preference between amniocentesis and CVS.
Main Methods:
- Decision analysis modeling was employed to compare three strategies: amniocentesis, CVS, and no prenatal testing.
- Probabilities were derived from obstetric and genetic literature.
- Utilities were assessed using standard reference gambles and rating scales from medical professionals and students.
Main Results:
- Amniocentesis demonstrated a higher expected utility than CVS by 0.1 utility units and no testing by 0.12 utility units.
- The decision remained robust across a range of plausible probability variations for test accuracy, abortion complications, and maternal morbidity.
- CVS became preferable if the utility of a first-trimester abortion significantly exceeded a second-trimester one, or if anxiety associated with awaiting CVS results was high.
Conclusions:
- Amniocentesis is generally the preferred prenatal diagnostic method for women aged 35, offering a better expected utility compared to CVS and no testing.
- The choice between amniocentesis and CVS can shift based on individual patient values, particularly regarding the timing of therapeutic abortion and the psychological impact of waiting for results.
- This analysis provides a framework for informed decision-making in prenatal genetic screening, highlighting the importance of patient-specific preferences.