Fetal Monitoring Often Tips Scales Toward Cesarean
Noninvasive fetal monitoring during labor contributes to the high rate of primary cesarean deliveries but could be harnessed to do the opposite, experts argued here at the Society for Maternal-Fetal Medicine meeting.
About a third of women have a first cesarean section based on "nonreassuring" fetal heart patterns seen with the electronic monitors despite almost no evidence for benefit, Alison G. Cahill, MD, of Washington University in St. Louis, explained during a symposium.
The goal of intrapartum monitoring is to catch signs of fetal distress before hypoxia leads to brain damage and, ultimately, death. Yet none of the 11 randomized controlled trials of electronic fetal monitoring showed fewer neonatal deaths or any other advantage over standard care, except for fewer seizures in one of the trials that didn't translate into a difference in long-term outcome.
Nevertheless, "we rolled this baby right out to the bedside because everybody had to have one," Cahill noted at the session on preventing first cesarean sections.
C-section carries risks for the mother and often keeps women from vaginal delivery on subsequent pregnancies. One million of the 3 million births that occur each year in the U.S. occur via cesarean delivery, she said.
Yet, of the 32% of primary cesareans done with fetal heart tracings as an indication, only a tiny portion reach the category III level at which the National Institute of Child Health and Human Development recommends cesarean delivery or operative delivery.
Most are taken to surgery over an indeterminate category II pattern, Cahill noted.
A prior study by her group found that a category II in the final 30 minutes before delivery had 100% sensitivity but only 2% specificity for cord gas and other short-term measures of outcome.
Certain components of the classification, though, had fairly good predictive accuracy. The area under the curve reached 0.78 to 0.83 for prolonged, variable, and late deceleration patterns and debt time.
Further research may be able to distinguish more objectively which category II patterns should be treated as normal instead of tipping the scale toward cesarean, Cahill suggested.
"Maybe it's not just electronic fetal monitoring, but how we use it," she argued.
There's poor evidence for any of the most common interventions tried based on a "nonreassuring" electronic monitoring readout -- oxygen or fluid bolus for the mother or tocolysis -- before heading to surgery.
In addition to further refining risk criteria, another strategy to optimize the benefits of electronic fetal monitoring and minimize the risk of it leading to an unnecessary primary cesarean delivery might be to move away from bedside interpretation, Cahill said.
She envisions this along the lines of a command center or cockpit model in which the tracings would read out remotely and only under certain concerning circumstances be called down to the bedside.
The real problem may be that potentially concerning electronic patterns turn into a sufficient excuse to go ahead when the woman or physician wants to do so for convenience sake, Methodius Tuuli, MD, MPH, also of Washington University at St. Louis, suggested in response to a question after his talk at the session.
"At some level many providers know that cesarean just for the sole purpose of maternal request is not looked upon favorably," he said. "My suspicion is that a physician who wants to perform a cesarean will perform it, the indication will just be different."
Retrospective studies have suggested an underestimation of elective cesarean, and "nonreassuring" fetal monitoring may turn from a secondary to a primary indication in that context, Tuuli proposed.
Session co-chair Sindhu Srinivas, MD, of the University of Pennsylvania in Philadelphia, called it a disguise for non-indicated C-sections.
A mediocre fetal heart pattern plus a patient who is tired of being induced can lead obstetricians to turn decision making over to the patient as to whether she wants a C-section, Cahill agreed.
"That's most likely to be coded as a nonreassuring heart rate tracing, but is it really?" she asked. "That's a very slippery slope that we're already on in terms of elective [cesarean]."