Refining the use of electronic fetal monitoring

Gaining reassurance

Although efforts to manage intrapartum fetal heart rate tracings focus largely on attempting to better predict who is at greatest risk for acidemia, it is important and worthwhile that we also attempt to determine whether a fetus with a category II tracing is not acidotic.

Research has consistently shown that the presence of accelerations, whether spontaneous or stimulated, is a highly reliable indicator of normal neonatal umbilical cord pH. It is therefore reasonable, when faced with indeterminate tracings (e.g., minimal variability), to consider scalp stimulation to elicit fetal heart rate acceleration. Scalp stimulation is the easiest noninvasive tool to employ to quickly secure clinical reassurance – within a couple of minutes – that the fetus is not acidotic.

For guidance on managing repetitive variable decelerations, amnioinfusion with normal saline is similarly worthy of consideration. It has been demonstrated (Level A evidence) to resolve variable fetal heart rate decelerations and reduce the incidence of cesarean delivery for nonreassuring fetal heart rate patterns. Both amnioinfusion and scalp stimulation are recommended in the 2014 ACOG/SMFM consensus statement on “Safe Prevention of the Primary Cesarean Delivery” (Obstet Gynecol. 2014 Mar;123[3]:693-711).

Oxygen administration, on the other hand, is ingrained in practice and is included in the American College of Obstetricians and Gynecologists’ practice bulletin on managing intrapartum fetal rate tracings. It is listed as a possible resuscitative measure for category II or III tracings, despite the fact that there are extremely limited data for its effectiveness or safety in labor.

Maureen S. Hamel, MD, and her colleagues at the Warren Albert Medical School at Brown University reviewed the literature and concluded that the only two randomized trials investigating the use of maternal oxygen supplementation in laboring women do not support the idea that supplementation may benefit the fetus. Moreover, they contended that oxygen supplementation may even be harmful (Am J Obstet Gynecol. 2014 Aug;211[2]:124-7).

If supplemental oxygen were a medication, we would want to know the dose, as well as the length and duration of administration before fetal heart rate tracing improved. We don’t know the answers to these questions.

There is research ongoing, both observational studies and at least one registered randomized clinical trial, that should provide more information and guidance on the impact of supplemental oxygen in the setting of category II fetal heart rate patterns. I do not expect these findings to resolve all the questions. We’re going to need a thorough body of work to provide us with definitive answers.
 

Dr. Cahill is the chief of the division of maternal-fetal medicine at Washington University in St. Louis. She reported having no financial disclosures relevant to this Master Class.