Elective, Marginal Inductions on the Rise
Appreciating the Risks
Studies have shown that induced labor is associated with an increase in epidurals, with the greatest risk of uterine rupture in patients with a scarred uterus, with perhaps an increase in instrumental vaginal deliveries, and with an increase in cesarean deliveries, particularly among nulliparas undergoing an induction with an unfavorable cervix.
Investigators of a large study published in 2005 found a 1.5-fold greater risk of diagnosing a nonreassuring fetal heart rate pattern, a twofold increase in the need for epidural anesthesia, and a 1.5-fold increased risk of having a cesarean delivery among women who had elective inductions of labor compared with women who had spontaneous labor.
The risks of oxytocin use are principally dose related. Excess or undesired uterine hyperstimulation and subsequent fetal heart rate decelerations (“hyperstimulation syndrome”) are the most common side effects. In addition, hyperstimulation is associated with a greater risk of abruptio placentae or uterine rupture. There does not appear to be a significant increase in adverse fetal outcomes from uterine tachysystole.
Uterine hyperstimulation is an adverse effect that is also dose-dependent for prostaglandins (misoprostol, dinoprostone) used as cervical-ripening agents. The potential risks associated with amniotomy include prolapse of the umbilical cord, chorioamnionitis, significant umbilical cord compression, and rupture of vasa previa. With close monitoring and proper precaution, these hazards are fortunately uncommon.
Even if no additional risks are found with elective and marginal indications, it is important to consider issues related to personnel and cost. In addition to increasing the primary cesarean rate—and even a small additional risk of cesarean delivery for nulliparous women who have their labor induced translates into a significantly larger number of cesarean deliveries nationally—labor that is induced requires more one-on-one care and thus more nurses or nursing time.
It also independently leads to significantly longer time in labor and delivery, as well as a prolonged maternal length of hospital stay. Investigators have demonstrated significant differences in the admission-to-delivery times and in-hospital costs between patients who have vaginal deliveries after induced labor as compared with those who have spontaneous labor, as well as with patients who have cesarean deliveries in both scenarios.
Other studies have shown that labor inductions can overload the labor and delivery departments of some hospitals during “popular” midweek times. Downstream, labor induction also leads to an excess number of vaginal births after cesarean (VBAC) or repeat cesarean procedures. I am convinced, moreover, that litigation will be a concern in the future, especially with our armamentarium of cervical ripening agents. When there is a negative outcome after induction, I believe we can anticipate an allegation of unnecessary induction due to the lack of a medical indication.
The frequency of elective inductions and inductions for marginal indications appears to be higher in community hospitals than at university hospitals. A study that my colleagues and I published in 2000 found that 5% of all labor inductions at a university hospital were elective or not medically indicated using the ACOG criteria. At two community hospitals, on the other hand, 44% and 57% of inductions were for elective reasons.
Physicians in academic settings—particularly those involved in clinical trials to assess the effectiveness of therapies for labor induction—are more likely to use the Bishop scoring system. The Bishop score, first described in 1964, is based on cervical dilation, effacement, consistency, and position, as well as on fetal station. Although the scale isn't used much outside of academia, the principles should be consistently and universally applied, particularly the assessment of dilation and cervical consistency.
Planning the Future
Investigators have looked and will continue to look for predictors of success and ideal conditions for labor induction, but at this point in time the only known conditions are a favorable cervix and a patient who has had a previous vaginal delivery. Multiparous women at term generally present with a more favorable cervix.
Right now, roughly half of women who have their labor induced—or roughly 10% of the overall pregnancy population—have an unfavorable cervix. Cesarean rates are high for nulliparas who undergo an induction with an unfavorable cervix. This is a picture that needs widespread attention and an awareness of the desirability of evidence-based decisions.
Obstetricians must construct consistent and evidence-based protocols for cervical ripening; formally evaluate physician and patient satisfaction with induction; and design and lead clinical trials to provide answers on the value of marginal indications.
In the meantime, labor induction rates for hospitals and physicians should be monitored, and patients should be educated about the risks of induction so that they can participate in decision making and be better able to balance concerns and benefits. It is quite possible that written consent may become a standard of care before any induction is undertaken.
