688
Letters
August 1990 Am J Obstet Gynecol
wave electrical activity also correlates with nonpropulsion in the intestines. 5 Martti Pulkkinen, MD Department of Obstetrics and Gynecology, University of Turku, 20520 Turku, Finland
Ulla-Marjut Jaakkola, PhD Department of Zoology, University of Turku, 20520 Turku, Finland
REFERENCES 1. Hodgson BJ, Talo A, Pauerstain CJ. Oviductal ovum surrogate movement: interrelation with muscular activity. Bioi Reprod 1977;16:394-7. 2. Pulkkinen MO, Talo A. Tubal physiologic consideration in ectopic pregnancy. Clin Obstet Gynecol 1987;30:164-72. 3. Talo A. Electrical and mechanical activity of the rabbit oviduct in vitro before and after ovulation. Bioi Reprod 1974; 11:335-45. 4. Jaakkola U-M. Muscular activity and luminal transport in the rat epididymis [Dissertation]. Turku, Finland: University of Turku, 1983:1-26. 5. Karaus M, Wienbeck M. Motor patterns in the colon. In: Kumar D, Gustavsson S, eds. Gastrointestinal motility. Chichester: John Wiley, 1988:211-27.
Appropriate screening tests To the Editors: Although I was impressed by the skill in which Dr. Chervenak and associates make an argument for the routine offering of medically unindicated ultrasonography to pregnant women (Chervenak FA, McCullough LB, Chervenak ]L. Prenatal informed consent for sonogram: an indication for obstetric ultrasonography. AM] OBSTET GVNECOL 1989;161:85760), there are some significant flaws in their logic that I feel must be pointed out. Without quoting actual data, the authors state "Established benefits currently outweigh harms, because the harms of false-positive and false-negative diagnosis can be minimized and the potential harms described by Kremkau may not ever be established." Although it is true that falsely abnormal results can be minimized in expert hands, there is little question that, when the routine offering of medically unindicated ultrasonograms becomes part of standard practice, most obstetric ultrasonography would be performed with insufficient expertise to obviate falsely abnormal results. The authors further state that the most that can currently be reasonably assumed is that some theoretical harms might outweigh some of the benefits. They correctly point out that there is no way to know reliably whether all of the harms will eventually outweigh all of the benefits, and they state that they believe that it's unlikely that a randomized trial will be performed, or that if performed that conclusive results would result. This seems to be an excellent argument against any clear benefit attributable to routine ultrasonography. The assumption that obstetricians will provide appropriate counseling to their patients so that they can make a correct informed decision is not only not supported, but the information that obstetricians might use in providing that counseling is nowhere suggested. For a woman to make a correct informed consent about ob-
taining an unindicated ultrasonogram, it would be necessary for her to know the utility of that ultrasonogram with respect to her health and the health of her infant and the potential cost to her and her infant of a falsely abnormal or a falsely normal result. In the current malpractice crisis a likely result of the routine offering of medically unindicated ultrasonograms would not be the provision of informal office ultrasonograms for a "fun look at the baby" but much more likely would be level 2 ultrasonograms performed by trained sonologists. Certainly, if studies are going to be done, this is how they are best done; however, the cost to the medical care system would be significant. At a time when many areas are struggling to increase access to care by extending Medicaid to women with incomes up to 185% of the federal poverty level, it seems onerous to add a medically unindicated diagnostic test. David A. Nagey, MD, PhD Division of Maternal-Fetal Medicine, University of Maryland, 22 South Greene St., Baltimore, MD 21201
Reply To the Editors: We appreciate Dr. Nagey's thoughtful comments and want to respond directly to his charge that "there are some significant flaws" in the logic of argument for prenatal informed consent for sonogram. Dr. Nagey's claim is that our argument is, in the technicallanguage of logic, invalid. In particular, he claims that a conclusion other than the one that we draw follows from our premises about the goods and harms of routine ultrasound. Dr. Nagey thinks that the conclusion should be that there is no "clear benefit attributable to routine ultrasonography." This conclusion cannot follow from our premises. It is a well-known principle of logical reasoning that it is impossible to derive from a premise a conclusion that is its contradiction. Moreover, it contradicts one of the premises, namely, that there are already established clear-cut benefits to routine ultrasonography (e.g., the detection of unsuspected fetal anomalies at a time during which the pregnant woman may elect changes in her obstetric management.'· 2 It is unfortunate that there is such a widespread misconception in the obstetric community about this certain, not uncertain, value of routine ultrasonography. What does follow from our premises is that there is no clear-cut balancing of the goods and harms of routine ultrasonography. This conclusion supports a woman's choice in this matter, namely, prenatal informed consent for sonogram. In adition to criticizing the "logic" of our argument, Nagey makes other comments we wish to address. First, he is correct in his concern about "insufficient expertise" in the performance of routine ultrasonography, a concern that we already expressed in our article. Second, his suggestions for the counseling of pregnant women constitute a useful enhancement of prenatal informed consent for sonogram. Third, we agree that increased cost may be a significant factor. However, as
Letters
August 1990 Am J Obstet Gynecol
wave electrical activity also correlates with nonpropulsion in the intestines. 5 Martti Pulkkinen, MD Department of Obstetrics and Gynecology, University of Turku, 20520 Turku, Finland
Ulla-Marjut Jaakkola, PhD Department of Zoology, University of Turku, 20520 Turku, Finland
REFERENCES 1. Hodgson BJ, Talo A, Pauerstain CJ. Oviductal ovum surrogate movement: interrelation with muscular activity. Bioi Reprod 1977;16:394-7. 2. Pulkkinen MO, Talo A. Tubal physiologic consideration in ectopic pregnancy. Clin Obstet Gynecol 1987;30:164-72. 3. Talo A. Electrical and mechanical activity of the rabbit oviduct in vitro before and after ovulation. Bioi Reprod 1974; 11:335-45. 4. Jaakkola U-M. Muscular activity and luminal transport in the rat epididymis [Dissertation]. Turku, Finland: University of Turku, 1983:1-26. 5. Karaus M, Wienbeck M. Motor patterns in the colon. In: Kumar D, Gustavsson S, eds. Gastrointestinal motility. Chichester: John Wiley, 1988:211-27.
Appropriate screening tests To the Editors: Although I was impressed by the skill in which Dr. Chervenak and associates make an argument for the routine offering of medically unindicated ultrasonography to pregnant women (Chervenak FA, McCullough LB, Chervenak ]L. Prenatal informed consent for sonogram: an indication for obstetric ultrasonography. AM] OBSTET GVNECOL 1989;161:85760), there are some significant flaws in their logic that I feel must be pointed out. Without quoting actual data, the authors state "Established benefits currently outweigh harms, because the harms of false-positive and false-negative diagnosis can be minimized and the potential harms described by Kremkau may not ever be established." Although it is true that falsely abnormal results can be minimized in expert hands, there is little question that, when the routine offering of medically unindicated ultrasonograms becomes part of standard practice, most obstetric ultrasonography would be performed with insufficient expertise to obviate falsely abnormal results. The authors further state that the most that can currently be reasonably assumed is that some theoretical harms might outweigh some of the benefits. They correctly point out that there is no way to know reliably whether all of the harms will eventually outweigh all of the benefits, and they state that they believe that it's unlikely that a randomized trial will be performed, or that if performed that conclusive results would result. This seems to be an excellent argument against any clear benefit attributable to routine ultrasonography. The assumption that obstetricians will provide appropriate counseling to their patients so that they can make a correct informed decision is not only not supported, but the information that obstetricians might use in providing that counseling is nowhere suggested. For a woman to make a correct informed consent about ob-
taining an unindicated ultrasonogram, it would be necessary for her to know the utility of that ultrasonogram with respect to her health and the health of her infant and the potential cost to her and her infant of a falsely abnormal or a falsely normal result. In the current malpractice crisis a likely result of the routine offering of medically unindicated ultrasonograms would not be the provision of informal office ultrasonograms for a "fun look at the baby" but much more likely would be level 2 ultrasonograms performed by trained sonologists. Certainly, if studies are going to be done, this is how they are best done; however, the cost to the medical care system would be significant. At a time when many areas are struggling to increase access to care by extending Medicaid to women with incomes up to 185% of the federal poverty level, it seems onerous to add a medically unindicated diagnostic test. David A. Nagey, MD, PhD Division of Maternal-Fetal Medicine, University of Maryland, 22 South Greene St., Baltimore, MD 21201
Reply To the Editors: We appreciate Dr. Nagey's thoughtful comments and want to respond directly to his charge that "there are some significant flaws" in the logic of argument for prenatal informed consent for sonogram. Dr. Nagey's claim is that our argument is, in the technicallanguage of logic, invalid. In particular, he claims that a conclusion other than the one that we draw follows from our premises about the goods and harms of routine ultrasound. Dr. Nagey thinks that the conclusion should be that there is no "clear benefit attributable to routine ultrasonography." This conclusion cannot follow from our premises. It is a well-known principle of logical reasoning that it is impossible to derive from a premise a conclusion that is its contradiction. Moreover, it contradicts one of the premises, namely, that there are already established clear-cut benefits to routine ultrasonography (e.g., the detection of unsuspected fetal anomalies at a time during which the pregnant woman may elect changes in her obstetric management.'· 2 It is unfortunate that there is such a widespread misconception in the obstetric community about this certain, not uncertain, value of routine ultrasonography. What does follow from our premises is that there is no clear-cut balancing of the goods and harms of routine ultrasonography. This conclusion supports a woman's choice in this matter, namely, prenatal informed consent for sonogram. In adition to criticizing the "logic" of our argument, Nagey makes other comments we wish to address. First, he is correct in his concern about "insufficient expertise" in the performance of routine ultrasonography, a concern that we already expressed in our article. Second, his suggestions for the counseling of pregnant women constitute a useful enhancement of prenatal informed consent for sonogram. Third, we agree that increased cost may be a significant factor. However, as
