Letters to the Editors www.AJOG.org Even more egregious was to print it in such a way as to make it look like an article vetted by the peer-review process and not clearly formatted to appear as an advertisement. This decision has less to do with the validity of the science than the integrity of the peer-review process. That said, however, I stand by the decision further in that the evidence presented would probably not be sufficient at this point to result in a recommendation of acceptance by qualified reviewers, but that is speculation. The irony is that you have certainly been able to get your point across through the letter I am responding to, which, by the way, we have chosen not to edit or censure. f Thomas J. Garite, MD Editor-in-Chief © 2010 Published by Mosby, Inc. doi: 10.1016/j.ajog.2009.11.009 Graded classification of fetal heart rate tracings: association with neonatal metabolic acidosis and neurologic morbidity TO THE EDITORS: The recent article by Elliot et al1 presenting the association of neonatal metabolic acidosis and neurologic morbidity and the 5-color FHR classification of Parer and Ikeda2 deserves comment. To understand the evolution of FHR patterns in association with adverse outcome, it would be important to know the category (normalcy) of each fetus both at the beginning of the labor as well as just before delivery. This would likely enable the authors to separate groups A (acidosis and encephalopathy) and I (acidosis only) according to problems arising during labor, during delivery, or previously. For this article, the analysis begins only 3 hours before delivery, without distinction of whether this time includes the first stage of labor or not. The authors present cumulative time (in 2-minute windows) in each color zone, although these brief times may not be consecutive or physiologically relevant. The average cumulative time in the red zone is brief (5.2– 6.3 minutes), irrespective of outcome group. This suggests either rapid response to these patterns or, alternatively, that these patterns change rapidly. As the authors acknowledge, the timing and benefit of intervention, if any, is not included. The positive association between adverse outcomes beginning with the “blue and above” zone suggests a continuum of deterioration and a penalty for delay. It seems likely that the pattern of deterioration is probably as important as the cumulative duration at any color. Does the deteriorating fetus go sequentially from green to orange/red or can it jump colors? Can red or orange go to green and vice versa? And how rapidly? About 25% of the encephalopathic group (A) had Apgars above 3 at 1 minute and above 6 at 5 minutes (Table 2), features that do not comport with “essential criteria” for assigning encephalopathy to the events of labor.3 Almost half (48.4%) of group A does not progress beyond the yellow zone, suggesting an unusually high false-negative (false-normal) rate. The study might profit from using low Apgar scores rather than base excess as the point of stratification. Low Apgar scores may have worse neurologic outcomes with “normal” pHs rather than “low” pHs.4 Finally, failure to recognize a benign pattern as the maternal heart rate may help to explain abnormal outcomes with apparently benign patterns.5 f Barry S. Schifrin, MD Kaiser Permanente-Los Angeles Medical Center 9018 Balboa Blvd. #595 Northridge, CA 91325 [email protected] REFERENCES 1. Elliott C, Warrick PA, Graham E, Hamilton EF. Graded classification of fetal heart rate tracings: association with neonatal metabolic acidosis and neurologic morbidity. Am J Obstet Gynecol 2010;202:258.e1-8. 2. Parer JT, Ikeda T. A framework for standardized management of intrapartum fetal heart rate patterns. Am J Obstet Gynecol 2007;197:26.e1-6. 3. American College of Obstetricians and Gynecologists. Neonatal encephalopathy and cerebral palsy: defining the pathogenesis and pathophysiology. Washington, DC: ACOG; 2003. 4. Dennis J, Johnson A, Mutch L, Yudkin P, Johnson P. Acid-base status at birth and neurodevelopmental outcome at four and one-half years. Am J Obstet Gynecol 1989;161:213-20. 5. Neilson DR Jr, Freeman RK, Mangan S. Signal ambiguity resulting in unexpected outcome with external fetal heart rate monitoring. Am J Obstet Gynecol 2008;198:717-24. © 2010 Mosby, Inc. All rights reserved. doi: 10.1016/j.ajog.2009.11.017 REPLY One article or brief response cannot adequately address all the pertinent comments raised in this thoughtful letter. We agree that it would be ideal to know the timing of injury (or, conversely, the “normalcy” of the infant) to separately analyze the infants with problems arising before or during labor. This was not possible, as we had no continuous measure of either fetal acidemia or neurologic status. Indeed, the unavailability of such techniques today is why we can only infer, not prove, the condition of the fetus, especially at times remote from birth. For this reason, we confined the analysis to a relatively short period, the last 3 hours, recognizing that all infants were probably not always in a state that we could only measure after birth. Neonatal magnetic resonance imaging or postmortem examinations have been used to determine what proportions of infants with hypoxic ischemic encephalopathy have isolated acute vs acute superimposed on chronic changes. Cowan et al1 examined 245 term infants exhibiting similar cord gases and neonatal encephalopathy and found that more than MAY 2010 American Journal of Obstetrics & Gynecology e11
