AMERICAN JOURNAL OF PERINATOLOGY/VOLUME 8, NUMBER 2
March 1991
FAILED INDUCTION OF LABOR DESPITE SEQUENTIAL PROSTAGLANDIN E2 THERAPY Peter T. Kamiskakis, M.D., William E Rayburn, M.D., Carl V. Smith, M.D., and Ralph E. Woods, M.D.
Preinduction cervical ripening with prostaglandin E2 (PGE2) is useful in minimizing the chances for a failed induction of labor. The lack of sufficient cervical dilation despite PGE2 and oxytocin therapy is uncommon. This investigation was undertaken to determine reasons for any failed inductions in pregnancies with pregel Bishop scores 4 or lower and requiring delivery within 24 hours. Fifteen (12.1%) of 124 eligible patients had failed inductions despite two 2.5 mg intravaginal doses. A finding in all the failures was a very unfavorable cervix (pregel Bishop score 0 to 2). The need for preterm delivery (33 to 37 weeks) was a common finding in the presence of a very unfavorable cervix. The data suggest that complicated pregnancies requiring delivery within 24 hours and failing to respond to sequential PGE2 therapy in the presence of a very unfavorable cervix may benefit from cesarean section without a prolonged induction.
Many double-blind, placebo-controlled studies have revealed that topical prostaglandin E2 (PGE2) results in changes in an unfavorable cervix and improved success with induction of labor.J However, it is expected that 40 to 50% of mothers who receive PGE2 will not achieve a more favorable cervix or go into labor.23 A review of our practice for sequential applications of intravaginal PGE2 in pregnancies requiring mandatory delivery permitted a search for reasons for any failed inductions. MATERIALS AND METHODS
The study was performed between October 1987 and April 1989. Candidates for the present investigation were patients with singleton pregnancies who required delivery within 24 hours because of obstetric or medical complications. Each subject was examined in the late afternoon or early evening before labor induction to assign a cervical Bishop score.4 To be enrolled, the presence of an unfavorable cervix (Bishop score 4 or lower) and lack of frequently recorded uterine contractions (more than 10 minutes apart) were necessary. The PGE2 gel was prepared by mixing a 20 mg PGE2 suppository (Prostin E2, Upjohn, Kalamazoo,
MI) with methylcellulose, so that each 3 ml plastic syringe contained 2.5 mg of the prostaglandin.5 After a reactive nonstress test or negative contraction stress test, the cervix was swabbed to remove any discharge. The previously frozen gel was thawed, then instilled into the portio vaginalis through a 16 gauge intravenous catheter. The patient remained recumbent, while uterine activity and the fetal heart rate were monitored continuously for at least 2 hours. A 250 mg (0.25 ml) dose of terbutaline (Brethine) was available for subcutaneous or intravenous injection in the event of uterine hyperstimulation (uncoordinated contractions of high frequency, either persisting or leading to decelerations of the fetal heart rate6). Uterine activity was considered sustained if contractions occurred at least every 5 minutes and lasted 45 seconds or more for at least 6 hours after PGE2 instillation. The patients were reevaluated in 6 hours after gel application. The examination was performed by the same person. If there was no sustained labor or change in the cervical Bishop score to 6 or more, a second dose of PGE2 was instilled, followed by another 6 hours of observation. A third dose was not administered, because recent reports have revealed no additional cervical ripening effect.2'7 An amniotomy was performed routinely as
Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of Nebraska Medical Center, Omaha, Nebraska Reprint requests: Dr. Rayburn, Department of Obstetrics and Gynecology, University of Nebraska Medical Center, 42nd and Dewey Avenue, Omaha, NE 68105
128
Copyright © 1991 by Thieme Medical Publishers, Inc., 381 Park Avenue South, New York, NY 10016. All rights reserved.
Downloaded by: Universite de Sherbrooke. Copyrighted material.
ABSTRACT
early as safely possible. If necessary, augmentation or induction of labor with oxytocin was begun at approximately 7 the next morning (12 hours after the initial dose). Oxytocin infusion followed guidelines recommended by the American College of Obstetricians and Gynecologists.8 The infusion was continued until delivery or for at least 8 hours, at which time the attending and resident physicians decided on further management. Intrapartum outcomes were evaluated. A failed induction involved no remarkable change in the cervix (Bishop score change less than 3) as determined by the same examiner (chief resident or investigators) and despite regular uterine contractions (every 3 minutes). Failure to progress was defined as an arrest of cervical dilation at 4 cm or more despite at least 2 hours of adequate labor. Average values were reported as a mean ± 1 standard deviation. The data were compared using two-tailed Student's t test, chisquare testing, or Fisher's exact probability test when appropriate. A p value less than 0.05 was considered significantly different. RESULTS
During the 19-month period, 149 patients were eligible for study. The average gestational age was 39.5 ± 1.4 weeks (range, 33 to 43 weeks). Primary indications for delivery included complications from postdates (61), pregnancy-induced or chronic hypertension (40), diabetes (33), and suspected severe fetal growth retardation (15). A significant change in the cervix to a more favorable condition (Bishop score 6 or higher) was found in 120 (80.5%) cases, and 132 (88.6%) had a successful induction of labor.
Table 1. Pregnancies Undergoing Successful or Failed Induction of Labor After Sequential PGE2 Therapy Induction of Labor
Material age Race (% white) Parity (% nulliparous) Gestational age (wk) < 38 38-42 > 42 Pregel Bishop score 0-2
Preinduction Bishop score 3s 6 Labor induced by oxytocin Route of delivery Vaginal Cesarean section Failed induction Failure to progress Fetal distress
Failure
Success (n = 132)
(n = 17)
p Value
24. 1 ± 2.7 82 (62.1%) 59 (44.7%)
24.;I ± 5.1 9 (52.9%) 10 (58.8%)
NS NS NS
10 (7.6%) 65 (49.2%) 57 (43.2%)
5 (29.4%) 9 (58.8%) 3 (17.6%)
12 (9.1%) 106 (80.3%)
17 (100%)
0 (-%)
< 0.01
< 0.001 < 0.001
44 (33.3%)
15 (88.2%)
< 0.001
116 (87.9%) 16 (12.1%) 0 14
0 (-%) 17 (100%) 17 0
< n nni
2
0
Table 1 compares the maternal ages, race, parity, gestational ages, and pregel Bishop scores of those pregnancies found to have successful or failed inductions. A very unfavorable cervix (pregel Bishop score 0 to 2) was found in all cases with a failed induction and was significantly more common than for pregnancies in which induction was successful (p
March 1991
FAILED INDUCTION OF LABOR DESPITE SEQUENTIAL PROSTAGLANDIN E2 THERAPY Peter T. Kamiskakis, M.D., William E Rayburn, M.D., Carl V. Smith, M.D., and Ralph E. Woods, M.D.
Preinduction cervical ripening with prostaglandin E2 (PGE2) is useful in minimizing the chances for a failed induction of labor. The lack of sufficient cervical dilation despite PGE2 and oxytocin therapy is uncommon. This investigation was undertaken to determine reasons for any failed inductions in pregnancies with pregel Bishop scores 4 or lower and requiring delivery within 24 hours. Fifteen (12.1%) of 124 eligible patients had failed inductions despite two 2.5 mg intravaginal doses. A finding in all the failures was a very unfavorable cervix (pregel Bishop score 0 to 2). The need for preterm delivery (33 to 37 weeks) was a common finding in the presence of a very unfavorable cervix. The data suggest that complicated pregnancies requiring delivery within 24 hours and failing to respond to sequential PGE2 therapy in the presence of a very unfavorable cervix may benefit from cesarean section without a prolonged induction.
Many double-blind, placebo-controlled studies have revealed that topical prostaglandin E2 (PGE2) results in changes in an unfavorable cervix and improved success with induction of labor.J However, it is expected that 40 to 50% of mothers who receive PGE2 will not achieve a more favorable cervix or go into labor.23 A review of our practice for sequential applications of intravaginal PGE2 in pregnancies requiring mandatory delivery permitted a search for reasons for any failed inductions. MATERIALS AND METHODS
The study was performed between October 1987 and April 1989. Candidates for the present investigation were patients with singleton pregnancies who required delivery within 24 hours because of obstetric or medical complications. Each subject was examined in the late afternoon or early evening before labor induction to assign a cervical Bishop score.4 To be enrolled, the presence of an unfavorable cervix (Bishop score 4 or lower) and lack of frequently recorded uterine contractions (more than 10 minutes apart) were necessary. The PGE2 gel was prepared by mixing a 20 mg PGE2 suppository (Prostin E2, Upjohn, Kalamazoo,
MI) with methylcellulose, so that each 3 ml plastic syringe contained 2.5 mg of the prostaglandin.5 After a reactive nonstress test or negative contraction stress test, the cervix was swabbed to remove any discharge. The previously frozen gel was thawed, then instilled into the portio vaginalis through a 16 gauge intravenous catheter. The patient remained recumbent, while uterine activity and the fetal heart rate were monitored continuously for at least 2 hours. A 250 mg (0.25 ml) dose of terbutaline (Brethine) was available for subcutaneous or intravenous injection in the event of uterine hyperstimulation (uncoordinated contractions of high frequency, either persisting or leading to decelerations of the fetal heart rate6). Uterine activity was considered sustained if contractions occurred at least every 5 minutes and lasted 45 seconds or more for at least 6 hours after PGE2 instillation. The patients were reevaluated in 6 hours after gel application. The examination was performed by the same person. If there was no sustained labor or change in the cervical Bishop score to 6 or more, a second dose of PGE2 was instilled, followed by another 6 hours of observation. A third dose was not administered, because recent reports have revealed no additional cervical ripening effect.2'7 An amniotomy was performed routinely as
Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of Nebraska Medical Center, Omaha, Nebraska Reprint requests: Dr. Rayburn, Department of Obstetrics and Gynecology, University of Nebraska Medical Center, 42nd and Dewey Avenue, Omaha, NE 68105
128
Copyright © 1991 by Thieme Medical Publishers, Inc., 381 Park Avenue South, New York, NY 10016. All rights reserved.
Downloaded by: Universite de Sherbrooke. Copyrighted material.
ABSTRACT
early as safely possible. If necessary, augmentation or induction of labor with oxytocin was begun at approximately 7 the next morning (12 hours after the initial dose). Oxytocin infusion followed guidelines recommended by the American College of Obstetricians and Gynecologists.8 The infusion was continued until delivery or for at least 8 hours, at which time the attending and resident physicians decided on further management. Intrapartum outcomes were evaluated. A failed induction involved no remarkable change in the cervix (Bishop score change less than 3) as determined by the same examiner (chief resident or investigators) and despite regular uterine contractions (every 3 minutes). Failure to progress was defined as an arrest of cervical dilation at 4 cm or more despite at least 2 hours of adequate labor. Average values were reported as a mean ± 1 standard deviation. The data were compared using two-tailed Student's t test, chisquare testing, or Fisher's exact probability test when appropriate. A p value less than 0.05 was considered significantly different. RESULTS
During the 19-month period, 149 patients were eligible for study. The average gestational age was 39.5 ± 1.4 weeks (range, 33 to 43 weeks). Primary indications for delivery included complications from postdates (61), pregnancy-induced or chronic hypertension (40), diabetes (33), and suspected severe fetal growth retardation (15). A significant change in the cervix to a more favorable condition (Bishop score 6 or higher) was found in 120 (80.5%) cases, and 132 (88.6%) had a successful induction of labor.
Table 1. Pregnancies Undergoing Successful or Failed Induction of Labor After Sequential PGE2 Therapy Induction of Labor
Material age Race (% white) Parity (% nulliparous) Gestational age (wk) < 38 38-42 > 42 Pregel Bishop score 0-2
Preinduction Bishop score 3s 6 Labor induced by oxytocin Route of delivery Vaginal Cesarean section Failed induction Failure to progress Fetal distress
Failure
Success (n = 132)
(n = 17)
p Value
24. 1 ± 2.7 82 (62.1%) 59 (44.7%)
24.;I ± 5.1 9 (52.9%) 10 (58.8%)
NS NS NS
10 (7.6%) 65 (49.2%) 57 (43.2%)
5 (29.4%) 9 (58.8%) 3 (17.6%)
12 (9.1%) 106 (80.3%)
17 (100%)
0 (-%)
< 0.01
< 0.001 < 0.001
44 (33.3%)
15 (88.2%)
< 0.001
116 (87.9%) 16 (12.1%) 0 14
0 (-%) 17 (100%) 17 0
< n nni
2
0
Table 1 compares the maternal ages, race, parity, gestational ages, and pregel Bishop scores of those pregnancies found to have successful or failed inductions. A very unfavorable cervix (pregel Bishop score 0 to 2) was found in all cases with a failed induction and was significantly more common than for pregnancies in which induction was successful (p
