By Jill Arnold
Here is the first and last paragraph of an editorial by a physician and consultant for Neoventa Medical in the current AJOG (June 2011).
As an obstetrician, present at the dawn of intrapartum electronic fetal monitoring (EFM), I had every expectation that EFM would improve perinatal outcomes and that these effects would be validated by robust clinical trials. However, metaanalysis of the randomized controlled trials (RCTs) comparing EFM with fetal heart tone auscultation failed to show that EFM decreases the most adverse perinatal events, mortality and hypoxic neurologic injury. Whether taken individually or collectively, the published trials were simply not adequately powered for these tragic outcomes which, fortunately, are quite rare. Consequently, 4 decades after its introduction into intrapartum care, the beneﬁts, if any, that may be attributable to EFM remain to be conclusively established.
EDIT 6/11/2011: Criticism was received that not enough of the original editorial was included in the post. Here are the next two paragraphs.
This current situation makes the study by Chen et al, potentially quite important. First, its sheer size far exceeds the preceding RCTs in aggregate. Second, unlike the earlier RCTs, this study did ﬁnd that EFM use was associated with signiﬁcantly reduced rates of neonatal mortality and low Apgar scores. Third, the improved survivorship of preterm fetuses receiving EFM is noteworthy because most of the previous trials focused on term or near term infants. Fourth, fewer neonatal seizures were observed in the “high-risk” group who received EFM. Finally, like the previous RCTS, EFM was associated with increased rates of operative vaginal deliveries, and cesarean section for “fetal distress.”
The authors opine that these encouraging results reﬂect the ability of EFM to provide “accurate and early detection of fetal acidemia” and to encourage appropriate interventions. As a retrospective cohort study rather than a prospective clinical usage trial, a post hoc, propter hoc relationship between the use of EFM and the neonatal outcomes observed cannot be absolutely determined. One could also argue that Apgar scores and/or neonatal seizures may not be adequate surrogate markers for hypoxic neurologic injury, because they can stem from numerous causes other than intrapartum oxygen deprivation. Further, birth certiﬁcates as data sources have some signiﬁcant limitations. Unlike complete medical records, they do not afford a glimpse into the actual fetal heart rate (FHR) tracings to determine whether they were properly interpreted or acted on. Other possibly relevant and important details of medical care and decision making that might have affected neonatal outcomes were not available to the investigators.
Returning to the central question implicit in this study, should every parturient, regardless of risk status, and with a pregnancy of any viable gestational age, receive continuous EFM? Chen et al do not have the deﬁnitive answer and neither do I. Given the enormity of undertaking the adequately powered RCT that should been done when EFM was introduced, it is unlikely that the desired level I evidence will be available any time soon. Even if such a study were considered, that is, comparing EFM with fetal heart tone auscultation, would there be sufﬁcient bed side work force to make it feasible? Lacking this study, and if we provisionally accept the hypothesis that EFM does improve perinatal outcomes, then the obvious corollary is to address the more frequent, possibly excessive number of obstetric interventions that accompany EFM and place many mothers at risk. Whether such interventions can be made more appropriately by making our fetal monitors more “intelligent” or by using well-studied adjunctive screening methods, or both, it behooves all who care for laboring patients to encourage work on this side of the equation as the overwhelming majority of laboring patients will continue to receive EFM, beneﬁcial or not, in the foreseeable future.
The editorial is online, so feel free to read and comment here.