Correspondence

Fetal Pulse Oximetry and Cesarean Delivery

N Engl J Med 2007; 356:1377-1378March 29, 2007

Article

To the Editor:

The study of fetal pulse oximetry and cesarean delivery reported by Bloom et al. (Nov. 23 issue)1 perhaps gives us an interesting insight into clinicians' behavior. The authors claim that fetal oxygen monitoring does not alter the rate of cesarean delivery. However, the reason for the lack of differences in cesarean rates and infant outcomes between the “masked” and “open” groups may reflect the difficulty of the clinicians in interpreting the fetal oxygen saturation values and therefore in including this information in intrapartum management. In support of this suggestion, among the patients with reassuring fetal heart-rate tracings, 25.1% had low oxygen saturation. If the clinicians had been acting on their knowledge of the oxygen saturation levels, one would expect a higher rate of cesarean section in the open group than was reported. The fact that intrapartum management was left to the discretion of the attending physician, without any clear guidelines on abnormalities in the level of fetal oxygen saturation and in the duration and frequency of low values, makes uncertain the authors' conclusion that the knowledge of fetal oxygen saturation may be of no benefit.

Michael J. Peek, Ph.D.
George S. Condous, M.B., B.S.
Ralph K.H. Nanan, Ph.D.
University of Sydney, Penrith 2750, Australia
peekm@wahs.nsw.gov.au

1 References

1. 1

   Bloom SL, Spong CY, Thom E, et al. Fetal pulse oximetry and cesarean delivery. N Engl J Med 2006;355:2195-2202
   Full Text | Web of Science | Medline

Author/Editor Response

We differ with the assertion by Dr. Peek and colleagues that we failed to provide attending physicians with clear guidelines regarding an abnormal level of fetal oxygen saturation. Indeed, we believe that a major strength of our study was the effort taken to ensure the proper education of our health care providers. These efforts, as summarized in the Methods section of the article, included three stages. First, specialized educators from the manufacturer participated in centralized training sessions, as well as individualized training sessions conducted at each of the 14 sites. These sessions included instruction on the interpretation of values for fetal oxygen saturation. Second, all attending physicians were required to pass examinations, which included questions regarding such interpretation, before they could participate in the trial. Third, a mandated refresher course was conducted after the second year of the trial. It is our belief that such efforts ensured that participating physicians had a clear understanding of how to interpret levels of fetal oxygen saturation and that our conclusions remain valid.

Regarding the concern that the rate of cesarean delivery should have been higher in the open group than it was, it is important to remember that values of fetal oxygen saturation are supposed to be interpreted in the context of a nonreassuring fetal heart rate. That is, one would not expect the group of women with a reassuring fetal heart rate to have had an increased rate of cesarean section.

Steven L. Bloom, M.D.
University of Texas Southwestern Medical Center, Dallas, TX 75390
steven.bloom@utsouthwestern.edu

Catherine Y. Spong, M.D.
National Institute of Child Health and Human Development, Bethesda, MD 20892

Elizabeth A. Thom, Ph.D.
George Washington University Biostatistics Center, Rockville, MD 20852

for the National Institute of Child Health and Human Development Maternal–Fetal Medicine Units Network