Correspondence
Electronic Fetal Monitoring in Predicting Cerebral Palsy
N Engl J Med 1996; 335:287-289July 25, 1996
- Article
To the Editor:
Nelson et al. (March 7 issue)1 studied the outcome of cerebral palsy and its association with specific heart-rate patterns on electronic fetal monitoring. Their analysis confirms, and Dr. MacDonald's companion editorial2 supports, previous studies and the generally held concept that most cerebral palsy is due not to intrapartum hypoxia, but to events that occurred earlier in pregnancy. Unfortunately, the authors' conclusion that their “findings arouse concern that . . . many cesarean sections [will] be performed without benefit and with the potential for harm” assumes that the sole end point to be averted by cesarean section, undertaken because of “evidence” of intrapartum hypoxia on electronic fetal monitoring, is cerebral palsy. We readily admit that electronic fetal monitoring is overused and misused and the results misinterpreted. But the technique is also misunderstood. Its goal is to identify a fetus with hypoxia or potential hypoxia during labor, and since investigators, including Nelson et al., have concluded that intrapartum hypoxia is not necessarily the culprit in cerebral palsy, let us look for other neonatal and infant end points with which to assess the value of electronic fetal monitoring and for other causes of cerebral palsy. Specifically, there is no mention of placental pathologic findings in the authors' analysis. Many placental abnormalities can cause sufficient hypoxia over long periods of time to alter brain growth in utero. We believe that the study of placental abnormalities is one of the missed opportunities the authors refer to in their concluding statements.
2 ReferencesJohn C. Hobbins, M.D.
University of Colorado Health Sciences Center, Denver, CO 80262Wes Tyson, M.D.
Children's Hospital, Denver, CO 802181
Nelson KB ,Dambrosia JM ,Ting TY ,Grether JK . Uncertain value of electronic fetal monitoring in predicting cerebral palsy. N Engl J Med 1996;334:613-618
Full Text | Web of Science | Medline2
MacDonald D . Cerebral palsy and intrapartum fetal monitoring. N Engl J Med 1996;334:659-660
Full Text | Web of Science | Medline
To the Editor:
The data presented by Nelson et al. derive from 10-year-old interpretations of patterns of fetal heart rate by diverse practitioners who used those patterns in managing labor. The authors nevertheless find a strong, independent correlation between certain fetal-heart-rate distress patterns and cerebral palsy. Extrapolating the 9.2 percent incidence of abnormal patterns in the control group to the entire population results in a false positive rate for cerebral palsy of 99.8 percent. Assuming a cesarean section would be the universal response, the authors imply that the increased rate of cesarean section offers little benefit, even considering its prevention of the occasional case of cerebral palsy. They seem to argue that in the absence of cerebral palsy, intervention by cesarean section is without benefit.
Newer insights into the relation of fetal behavior and neurologic injury to patterns of fetal heart rate gleaned over the past decade are not discussed by the authors.1-4 The authors analyze a subgroup of fetal-heart-rate patterns described as decreased beat-to-beat variability and late decelerations (defined as “bradycardia”). The tracings are unavailable, the descriptions are incomplete, and other patterns are not considered. Persistently decreased beat-to-beat variability with or without decelerations from the outset of labor most likely reflects antepartum, not intrapartum, injury.2-4 These circumstances prevailed in over half the cases of cerebral palsy in several series and were not modified by cesarean section.2-4 In about 80 percent of these cases, the fetal-heart-rate patterns were normal in the preceding week.4 Transient changes in the fetal heart rate produced by medication or anesthesia are of no consequence and require no intervention. Only if the fetal-heart-rate patterns were initially normal and later progressively abnormal might intrapartum care improve the outcome.
By failing to consider the timing and duration of these fetal-heart-rate patterns and their relation to other measures of outcome, the authors preclude any estimate of either how often intervention averted a more serious outcome or how often the failure to intervene contributed to an adverse outcome. These patterns do not invariably lead to cesarean section: cesarean section was performed in only about one third of cases in this and other reports involving similar fetal-heart-rate patterns.3,4
Does it not make more sense to advocate greater discrimination in the evaluation of fetal-heart-rate patterns and to focus less on the rate of cesarean section? Fetal-heart-rate patterns may indeed permit an understanding of the timing, mechanism, and preventability of injury and thus inform strategies for the prevention of both cerebral palsy and unnecessary cesarean section.
4 ReferencesBarry S. Schifrin, M.D.
18425 Burbank Blvd., Tarzana, CA 91356Steven A. Myers, D.O.
Mount Sinai Hospital, Chicago, IL 60612-1914Wayne R. Cohen, M.D.
Sinai Hospital of Baltimore, Baltimore, MD 21215-52711
Koyanagi T ,Horimoto N ,Maeda H , et al. Abnormal behavioral patterns in the human fetus at term: correlation with lesion sites in the central nervous system after birth. J Child Neurol 1993;8:19-26
CrossRef | Web of Science | Medline2
Phelan JP ,Ahn MO . Perinatal observations in forty-eight neurologically impaired term infants. Am J Obstet Gynecol 1994;171:424-431
Web of Science | Medline3
Shields JR ,Schifrin BS . Perinatal antecedents of cerebral palsy. Obstet Gynecol 1988;71:899-905
Web of Science | Medline4
Schifrin BS ,Hamilton-Rubinstein T ,Shields JR . Fetal heart rate patterns and the timing of fetal injury. J Perinatol 1994;14:174-181
Medline
To the Editor:
Nelson et al. find that cesarean section is not associated with a significantly altered risk of cerebral palsy in children with multiple late decelerations. Nor, as they point out, was there any evidence that electronic fetal monitoring is associated with improved outcomes. Yet neither the authors nor MacDonald in his editorial comes to the obvious conclusions: that absent special circumstances, electronic fetal monitoring should be abandoned, and that cesarean section (in view of its risks) should not be performed unless there is some indication other than late decelerations.
A greater bluntness would have been desirable. It is difficult enough to bring about a change in physicians' behavior even when a spade is forthrightly called a spade. I fear that many obstetricians who routinely use electronic fetal monitoring and perform cesarean sections for late decelerations will continue to do so as a result of inertia even after they have learned of the study results. I would like to see the authors and the editorialist either endorse the conclusions I draw in no uncertain terms or dispute them.
Jay A. Gold, M.D., J.D., M.P.H.
Wisconsin Peer Review Organization, Madison, WI 53713Author/Editor Response
The authors reply:
To the Editor: We appreciate the interest in our recent paper, which reports that the use of electronic fetal monitoring to identify an increase in risk from 1 per 15,000 (the estimated frequency of birth-asphyxia–related cerebral palsy in term infants) to 3 per 15,000 may not provide a sound basis for management decisions. Certainly, there are indications for which cesarean section benefits mother and child. However, performing cesarean sections on the basis of findings from electronic fetal monitoring in the hope of preventing cerebral palsy may not provide a net benefit. Electronic fetal monitoring may be beneficial for other outcomes, but the results of randomized trials and a meta-analysis of them do not make a strong case for that position.1 We are studying other causes of cerebral palsy and in doing so are using placental pathology; however, that is not what this paper was about.
In a British study,2 32 percent of control subjects had “ominous tracings” in the second stage of labor. What can it mean to say that characteristics present in 32 percent of apparently normal people are “ominous”? We join with Schifrin et al. in advocating greater discrimination in the evaluation of fetal-heart-rate patterns and hope to see studies that provide a credible basis for such discriminations. However, the papers to which Schifrin et al. refer are highly selected case series from which generalizations are inappropriate. Proponents of electronic fetal monitoring should offer hypotheses about the relation of specific patterns to outcomes and test those hypotheses in methodologically appropriate studies, to establish which fetal-heart-rate patterns justify which action under which clinical circumstances.
Dr. Gold's letter calls for an unambiguous position on electronic fetal monitoring in general, but we can address only the outcome we have studied, cerebral palsy. We agree that cesarean section should probably not be performed for the prevention of cerebral palsy unless there are indications other than late decelerations. But medicolegal pressures can influence physicians' decisions; it is not only obstetricians who will have to be educated in order to bring behavior more in line with medical evidence. (Another reason for the widespread use of electronic fetal monitoring is the assumption that safe monitoring by intermittent auscultation requires more nursing time even for low-risk patients, an assumption that has been challenged.3)
Electronic fetal monitoring is used as a screening test, but screening tests are valuable only if a diagnostic test and an effective treatment exist. As Fiona Stanley pointed out,4 electronic fetal monitoring used in the hope of preventing cerebral palsy is a screening test for which there is no diagnostic test until a year or more after delivery and no therapy of proven benefit.
4 ReferencesKarin B. Nelson, M.D.
James Dambrosia, Ph.D.
National Institutes of Health, Bethesda, MD 20892-9130Judith K. Grether, Ph.D.
California Department of Health Services, Emeryville, CA 94608-18111
Thacker SB ,Stroup DF ,Peterson HB . Efficacy and safety of intrapartum electronic fetal monitoring: an update. Obstet Gynecol 1995;86:613-620
Web of Science | Medline2
Gaffney G ,Sellers S ,Flavell V ,Squier M ,Johnson A . Case-control study of intrapartum care, cerebral palsy, and perinatal death. BMJ 1994;308:743-750
CrossRef | Web of Science | Medline3
Sandmire HF ,DeMott RK . Auscultation of the fetal heart presents advantages over electronic monitoring. Wis Med J 1995;94:661-663
Medline4
Stanley FJ. Litigation versus science: what's driving decision makingin medicine? Eleanor Shaw Lecture, Melbourne, Australia, August 29, 1995.
Author/Editor Response
In response to Dr. Gold's comments: with one exception1 there are no data to show that continuous electronic monitoring of the fetal heart during labor yields poorer results than intermittent auscultation. Both seem to result in the same rates of intrapartum and neonatal mortality from hypoxia and long-term morbidity. Many delivery units are unable to supply one-to-one nursing care and will argue that electronic monitoring enables intrapartum fetal care to be available to many mothers in facilities with restrictions on nursing availability. I believe it is possible for one nurse to supervise two laboring mothers at one time, but I think that every mother deserves one-to-one nursing care during labor. Rather than abandon electronic fetal monitoring, I would support the greater use of intrapartum scalp sampling to clarify the meaning of nonreassuring tracings.
With respect to the comments of Drs. Hobbins and Tyson, I would, without having any specialized knowledge, support their view that we must continue to seek the causes of cerebral palsy and that placental abnormalities may be a major source of such causes.
1 ReferencesDermot MacDonald, M.B., M.A.O.
National Maternity Hospital, Dublin 2, Ireland1
Shy KK ,Luthy DA ,Bennett FC , et al. Effects of electronic fetal-heart-rate monitoring, as compared with periodic auscultation, on the neurologic development of premature infants. N Engl J Med 1990;322:588-593
Full Text | Web of Science | Medline
- Citing Articles (3)
Citing Articles
1
Barry S. Schifrin, Stewart Ater. (2006) Fetal hypoxic and ischemic injuries. Current Opinion in Obstetrics and Gynecology 18:2, 112-122
CrossRef2
B SCHIFRIN. (2004) The CTG and the timing and mechanism of fetal neurological injuries. Best Practice & Research Clinical Obstetrics & Gynaecology 18:3, 437-456
CrossRef3
Hirobumi Asakura, Hisashi Ichikawa, Masao Nakabayashi, Kazuto Ando, Kazuhiko Kaneko, Masakiyo Kawabata, Akihiro Tani, Masashi Satoh, Katsuyuki Takahashi, Shouichi Sakamoto. (2000) Perinatal Risk Factors Related to Neurologic Outcomes of Term Newborns with Asphyxia at Birth: A Prospective Study. Journal of Obstetrics and Gynaecology Research 26:5, 313-324
CrossRef
