Preinduction Cervical Ripening Significantly Increases Risk of Cesarean

Peggy Peck

April 30, 2003

April 30, 2003 (New Orleans) -- Results of a retrospective analysis of charts from 1,268 multiparous women indicate that elective induction with preinduction cervical ripening significantly increases the risk of cesarean delivery, evidence, said the lead investigator, that "this practice should be stopped."

Matthew K. Hoffmann, MD, MPH, told Medscape that "40% of the deliveries in our system are elective inductions, which is twice the rate reported nationally. I think many of these are convenience inductions done to suit the schedules of both the mother and the obstetrician." He said that he thinks the high rate of elective inductions increases the likelihood of "finding an unfavorable cervix, which then leads to the use of preinduction cervical ripening." Dr. Hoffmann is an associate professor at Christiana Care Health System, Newark, Delaware, and Jefferson Medical College in Philadelphia.

He presented his study here at the 51st annual meeting of the American College of Obstetricians and Gynecologists.

All of the women in the study had one prior vaginal delivery. The women delivered between July 2000 and June 2001 and were identified using a contemporaneously maintained perinatal database. The study excluded women who had a fetal or maternal indication for induction or for cesarean section. Women with diabetes were also excluded.

The remaining women were divided into three groups: spontaneous delivery, elective induction, and elective induction with preinduction cervical ripening. All preinduction cervical ripening was performed using Foley catheter method.

Four hundred and fifty-four women had elective induction of labor without preinduction cervical ripening, while 67 women were induced with preinduction ripening. The remaining 747 women had spontaneous onset of labor.

Among women who underwent preinduction cervical ripening, "11.94% had cesarean sections, compared to 3.30% of the women with elective induction without ripening and 2.14% of the spontaneous labor cohort. So preinduction cervical ripening was associated with a five-fold increase in risk for cesarean section," said Dr. Hoffmann.

Overall the cesarean delivery rate was 3.7%, he said.

"Only two factors were independent predictors of cesarean section: birth weight and preinduction cervical ripening," he said. "Among women who had cervical ripening this increased risk was associated with fetal distress and dystocia."

Dr. Hoffmann told Medscape that based on his study, "the use of preinduction cervical ripening should be stopped" in women who opt for elective induction. "I think that when a woman presents with an unfavorable cervix, the obstetrician should simply wait to let nature take its course." The other option, he said, would be "to simply do a cesarean immediately rather than putting the woman and the fetus through hours and hours of failed labor."

Since Dr. Hoffmann's study is a "retrospective chart review it is difficult to know if these are truly elective inductions or if there was some medical indication," William F. Rayburn, MD, professor and chair of the department of obstetrics and gynecology at the University of New Mexico Health Sciences Center in Albuquerque, told Medscape.

"Often this information is missing from the chart," he pointed out, "and in the absence of information the assumption is that it would be an elective procedure." With that caveat, Dr. Rayburn nonetheless agreed with Dr. Hoffmann's finding that the cesarean delivery rate seen in the preinduction cohort was "high, very high, and that is of concern.

"Moreover, that 40% elective induction rate is twice the national average that we reported in earlier studies, so that is surprising," said Dr. Rayburn, who has written several papers that raised concerns about the rate of elective induction.

But Dr. Rayburn said, "the overall 3.07% cesarean delivery rate reported by Dr. Hoffmann is actually much lower than one would expect. That, too, is surprising."

Asked to explain the high elective induction rate, Dr. Hoffmann said he thinks it reflects "our unique environment. We have many large obstetrical practices and women want to be delivered by a particular doctor. That doctor may only deliver on Thursdays so it is not unusual for women to be given an appointment to be induced three months before the due date."

ACOG 51st Annual Clinical Meeting: Abstract 7S. Presented April 29, 2003.

Reviewed by Gary D. Vogin, MD

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