Medical Professional Liability and the Delivery of Obstetrical Care Volume II, An Interdisciplinary Review (1989) / Chapter Skim
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Medical Professional Liability in Screening for Genetic Disorders and Birth Defects
Medical Professional Liability in Screening for Genetic Disorders and Birth Defects
Pages 41-56
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From page 41... ...
, screening present (for fetal neural tube defects using maternal serum alpha-fetoprotein—MSAFP) , and screening future (for a wide range of disorders using DNA-based tests)
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From page 42... ...
When tests for different disorders but with the same sensitivity and specificity are compared, the one for the least common disease will have the greatest chance of being falsely positive. The predictive value of a positive test result depends not only on specificity and sensitivity but on the incidence of the disorder being tested.
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From page 43... ...
Unfortunately, neither the effectiveness of the low-phenylalanine diet, nor the sensitivity and specificity of the screening test, nor the reliability of the laboratories performing it was established before newborns were routinely screened and those with positive results started on treatment.6 7 Without knowledge of the imperfections of the new technology, the probability of unfavorable outcomes and, consequently, of malpractice suits increased.
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From page 44... ...
The infant had been screened as a newborn, and the results had been reported as normal. This event, together with the finding that more boys with PKU were being detected by newborn screening than were girIs~espite the fact that the genetics of the disorder suggested that equal numbers should be detected prompted me and my colleagues at Hopkins to conduct a survey of PKU clinics and state health departments.9 We discovered 23 false negatives and found that the probability of PKU infants being missed was greater the earlier they were screened, particularly for girls.
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From page 45... ...
A more recent survey of state health departments by investigators at the CDC revealed 43 PKU infants who had been missed by screening, a minimum of 1.4 percent of all PKU infants screened.~5 (Health departments are unlikely to know of all missed cases.) A few ofthe infants were missed because a specimen never reached the screening laboratory; a few others were missed because a positive test result was never followed up.
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From page 46... ...
Although their occurrence is genetically influenced in at least some cases, more than 95 percent of affected infants are born to families without a previous history of anencephaly or open spine bifida. The association between elevated concentrations of AFP in the blood of women in the second trimester of pregnancy and open neural tube defects was discovered by Brock and his colleagues in Scotland in 1974.~7 Medical centers serving areas in the United Kingdom in which the frequency of open spine bifida was several times higher than it was in the United States soon began to screen.
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From page 47... ...
Follow-up for MSAFP tests includes a repeat MSAFP determination; amniocentesis, with measurement of the AFP and characterization of the acety~cholinesterase in the amniotic fluid; and ultrasound examination of the spinal region of the fetus. If these studies are properly conducted and interpreted, the chance that an unaffected fetus will be aborted is less than 1 in 200.~9 When such high probabilities can be attained at costs that are low compared with the costs oftreating the disorder without early detection, which is the case for both PKU20 and neural tube defects, screening is economically justified, provided that most people will accept screening and its sequlae.
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From page 48... ...
The rationale was to give obstetricians "the best possible defense" when women who were not tested had babies with neural tube defects.27 Although the ACOG urged obstetricians to learn more about MSAFP screening and follow-up, it failed to recognize that until obstetricians knew more about the procedures, malpractice could arise out of misuse as well as nonuse of the test. At least one state, California, has regulated MSAFP testing.
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From page 49... ...
A more fundamental solution is to teach medical students and house officers to appreciate the dangers and difficulties posed by new technologies, including, in the area of screening, the probabilistic nature of test results. SCREENING FUTURE: DNA-BASED TESTING Until the advent of recombinant DNA technology, relatively few genetic disorders or birth defects were amenable to screening.
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From page 50... ...
Until we can determine the presence of these other factory task in which success may prove elusive the predictive value of positive DNA-based tests may not be very high. Furthermore, until we understand more about the early, presymptomatic stages of these disorders, tests that confirm or cancel the positive screening test result will not be available.
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From page 51... ...
Even if people do not want to know their own risks, insurance companies and employers will be interested in using genetic screening to identify people at risk for future disease or premature death. Insurance companies will not insure people at increased risk of some costly diseases— at least not at standard premiums—and employers could refuse to hire workers at increased risk to keep their health benefits costs down and reduce the chance of harmful reactions to the work place on the part of susceptible persons.
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From page 52... ...
For those genetic disorders whose manifestations can be prevented, delayed, or ameliorated only by presymptomatic intervention, genetic screening provides a unique opportunity to reduce the magnitude of disability. For genetic disorders for which effective interventions have not been developed, screening can identify individuals or couples at risk of having affected offspring, giving them the option of avoiding conception (and having children through adoption, surrogate motherhood, or ovum, embryo, or sperm donation)
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From page 53... ...
With proper understanding, they would not hesitate to screen again if they encountered a high-risk situation in a person with a negative test result, and they would confirm positive screening test results before taking potentially dangerous or irreversible action. In offering screening and in communicating results, properly trained providers would counsel their patients about the uncertainty attached to screening.
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From page 54... ...
1981. Amniotic fluid acetylcholinesterase electrophoresis as a secondary test in the diagnosis of anencephaly and open spine bifida in early pregnancy.
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From page 55... ...
Zeckhauser.1987. Cost effectiveness of prenatal screening for neural tube defects.
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