The following guidelines are intended only as a general educational resource for hospitals
and clinicians, and are not intended to reflect or establish a standard of care or to replace
individual clinician judgment and medical decision making for specific healthcare
environments and patient situations.
Guideline for Cervical Ripening
Approved February, 2011
INTRODUCTION
The benefits of labor induction and cervical ripening must be weighed against the potential
maternal and fetal risks associated with this procedure (1). The induction of labor may increase
the likelihood of neonatal complications or result in unnecessary cesarean section. These risks
may be necessary to assume in complicated pregnancies, in which prolongation of gestation
presents further risk to the mother or fetus.
Prior to initiating cervical ripening, the patient should be counseled about the indications for the
procedure, the agents and methods to be employed, and the risks of failure, cesarean delivery, or
fetal compromise.
A physician capable of performing cesarean section should be readily available during the
induction or augmentation of labor (2).
UNIT STRUCTURE
Each hospital’s department of obstetrics should develop a written protocol for the use of cervical
ripening agents. A protocol is recommended to reduce medication dosing error and improve
patient assessment.
Elements of protocols should include (2):
 Indications for the use of cervical ripening agents.
 Methods for preparation and administration of cervical ripening agents.
 Qualifications of staff authorized to administer these agents and monitor patients.
 The level of the initial and subsequent doses.
 The timing of subsequent labor induction with oxytocin.
 A protocol for patient assessment, including definitions of normal and abnormal
conditions evaluated by monitoring.
 Methods of managing complications should they develop.
DEFINITIONS
Elective Induction: Induction of labor when there is no clear medical benefit to mother or child
for delivery at that point in time compared with continuation of pregnancy.
Medically Indicated Induction: Induction of labor when there is clear medical benefit to either
mother or baby from ending the pregnancy rather than continuing with it.
Cervical Ripening: The process of causing softening of the cervix, ultimately leading to partial
cervical dilatation and effacement. This is employed when the cervix is considered unripe, prior
to induction of labor, for the purpose of increasing success with induction of labor.
Induction of Labor: The purposeful stimulation of uterine contractions for the purpose of
accomplishing delivery, prior to the natural onset of labor.
Labor: Painful and regular contractions with progressive cervical change.
Tachysystole: More than 5 contractions in 10 minutes, averaged over a 30 minute period of
time.
INDICATIONS
The use of cervical ripening methods is indicated when labor induction is indicated, but the
cervix is considered unripe or unfavorable for induction of labor.
For a review of indications for induction of labor, refer to the NNEPQIN publications,
“Guideline for Medically Indicated Induction of Labor” and “Guideline Suggestions for Elective
Induction of Labor”.
PATIENT ASSESSMENT
A thorough evaluation of the mother and fetus is necessary prior to induction in order to identify
potential risks and to estimate the likelihood of success.
Factors to assess include:
 The patient’s pregnancy history and medical history
 Gestational age of the fetus
 Estimated fetal weight
 The fetal presenting part
 The adequacy of the pelvis
 The cervical status
Gestational age and fetal lung maturity
In cases of indicated induction of labor prior to term, the risks of fetal prematurity, primarily
fetal respiratory compromise, need to be weighed against the benefits of early delivery.
The frequencies of respiratory morbidity are reduced when delivery is at 39 weeks (OR 0.6) as
compared to 38 weeks (OR 1.4) or 37 weeks (OR 2.5) (3) (Level B).
ACOG has published criteria for confirmation of term gestation (39 weeks or greater) (4).
 Fetal heart tones have been documented for 30 weeks by Doppler.
 Thirty-six weeks have elapsed since a serum or urine hCG based pregnancy test was
reported to be positive.
 Ultrasound measurement at less than 20 weeks gestation supports gestational age of 39
weeks or greater.
Overall neonatal outcome may be improved with delivery at 39 weeks or greater, compared to
delivery from 36-38 weeks in the presence of pulmonary maturity determined by amniocentesis
(5) (Level B).
Cervical status
The status of the cervix is the most important predictor of the ability to reach the active phase of
labor and achieve vaginal delivery.
The best assessment of the cervical status is by use of the Bishop score. A high Bishop score
(variably defined as ≥5 or ≥8) indicates a similar likelihood of vaginal birth whether labor is
spontaneous or induced. A low Bishop score (<6) is associated with a higher rate of failed
induction of labor, particularly in nulliparous women (6) (Level B).
When the cervix is unfavorable, cervical ripening should be considered prior to induction of
labor.
BISHOP SCORING SYSTEM (7)
SCORE
0
1
2
3
Dilation
(cm)
Closed
1-2
3-4
>/=5
Effacement
(%)
0-30
40-50
60-70
>/=80
Station
Consistency
Position
-3
-2
-1,0
>/=+1
Firm
Medium
Soft
-
Posterior
Mid
Anterior
-
CERVICAL RIPENING METHODS
Limited data exist regarding the optimal methods of cervical ripening. Effective methods
include the use of mechanical dilators or prostaglandins. Compared with prostaglandins, balloon
catheters result in similar efficacy and cesarean rates with lower rates of tachysystole, but require
the use of oxytocin more often (8) (Level A).
Mechanical methods
Commonly employed methods of mechanical cervical ripening include balloon catheters,
hygroscopic dilators, membrane sweeping and extraamniotic saline infusion.




In women undergoing labor induction with an unripe cervix, the employment of a balloon
catheter or cervical dilators (hygroscopic or osmotic) results in a decreased rate of
cesarean birth compared to the use of oxytocin alone (9) (Level B).
Osmotic dilators (Laminaria) may be associated with increased peripartum infections
(10) (Level A).
Membrane sweeping (stripping) increases the likelihood of spontaneous labor within 48
hours and may reduce the need for induction of labor by other methods (11) (Level B).
Extraamniotic saline infusion may be no more effective than use of a balloon catheter
alone (12) (Level A).
Balloon catheters are associated with an increased risk of maternal infection (13) (Level A), and
have the potential to displace a low-lying placenta.
 A #16 Foley catheter can be used, or there are specially designed catheters for cervical
dilatation.
 After placement, 30-80 mL of fluid is used to distend the balloon. Using an 80 mL
volume is associated with a shorter duration of ripening (14) (Level A).
 Often the balloon is extruded spontaneously within 12 hours. Otherwise the balloon is
removed after 12-24 hours.
 A randomized trial demonstrated that time to delivery was not improved by administering
oxytocin while the catheter was in place (15) (Level A).
 Fetal monitoring should be performed with placement of the catheter and inflation of the
balloon, then continued for 30 minutes, then additionally per risk status or if bleeding
develops.
Prostaglandins
PGE2 (dinoprostone) and PGE1 (misoprosol) have been shown to be as effective as or more
effective than mechanical methods of cervical ripening. Rates of tachysystole with or without
subsequent fetal heart rate changes are higher for misoprostol compared to dinoprostone or
oxytocin (16) (Level B).
 Maternal vital signs and the FHR pattern should be assessed prior to cervical ripening (2).
 Dinoprostone 2.5 mg intracervical gel (Prepidil) can be repeated every 6-12 hours up to 3
total doses, with oxytocin initiated 6-12 hours after the last dose (manufacturer’s
recommendations).
 Dinoprostone 10 mg vaginal insert (Cervidil) can be left in place until the onset of labor
or up to 12 hours, with oxytocin initiated 30-60 minutes after removal (manufacturer’s
recommendations).
 Misoprostol is given initially in a 25 mcg dose (one quarter of a 100 mcg tablet)
intravaginally and can be repeated every 3-6 hours (16) (Level A). Higher doses (50 mcg
every 3-6 hours) may be considered if there is a failure to respond. Rates of tachysystole
are higher with the 50 mcg dose (17) (Level B).
 Misoprostol can be given orally in 50 mcg doses. Oral dosing of misoprostol may be less
effective compared to vaginal administration (18) (Level A).
 After vaginal administration of prostaglandin gel or tablet preparations, the mother
should remain recumbent for at least 30 minutes. After administration of the
dinoprostone vaginal insert, the mother should remain recumbent for two hours.
 When misoprostol is administered for cervical ripening, oxytocin may be administered
for induction of labor 4 hours after the last misoprostol dose. (17) (Level B).


When prostaglandins are administered, the fetal heart rate and uterine activity should be
monitored continuously for an initial observation period of 30 min to 2 hours, and then
further as determined by individual indications for the induction and fetal status.
Monitoring should be continued if regular uterine contractions persist (18, 19) (Level B).
When the dinoprosone vaginal insert is used, continuous monitoring should be used while
the device is in place and continued for 15 minutes after removal (manufacturer’s
recommendations).
COMPLICATIONS
Complications of uterine stimulation include the development of abnormal fetal heart rate
patterns, tachysystole, and failure of induction of labor.
Abnormal fetal heart rate patterns
 Should a category III FHR pattern develop, prompt evaluation is necessary. Cervical
ripening should be discontinued. Additional measures include maternal oxygen
administration, lateral positioning of the mother, and increased IV fluid administration.
The administration of terbutaline or other tocolytics may be considered. If the pattern is
unresolved, prompt delivery is necessary (20) (Level A).
 Category II tracings require evaluation. Similar measures to those above may be
necessary with category II FHR patterns, especially those that involve fetal bradycardia,
tachycardia, minimal or absent variability, the absence of accelerations after fetal
stimulation, or recurrent or prolonged decelerations (20) (Level B).
Tachysystole
 Tachysystole in response to prostaglandins, without associated fetal heart rate
decelerations, does not appear to be associated with a significant increase in adverse fetal
outcome (21, 22) (Level A).
 When tachysystole is present without FHR abnormalities, further monitoring is indicated.
The mother should be repositioned to a lateral position, left or right. Administration of a
bolus of IV fluids may be considered.
 If tachysystole occurs with vaginal misoprostol or dinoprosone gel, irrigation of the
cervix and vagina is not effective.
 If tachysystole occurs while the dinoprostone vaginal insert is present, it should be
removed.
Failed induction of labor
 There are no standards for what situations constitute a failed induction of labor.
Adequate time should be allowed for cervical ripening and the initiation of labor before a
determination of a failed induction of labor can be made.
 In general, the beginning of active phase of labor is felt to occur when the cervix is 4-5
cm dilated and there is associated effacement to 80% (23) (Level C).

Allowing a period of 12-18 hours of latent phase labor after amniotomy and oxytocin
administration should be considered before the diagnosis of failed induction is made (24,
25) (Level B).
SPECIAL CONSIDERATIONS
Fetal demise
Induction of labor after fetal demise in the third trimester (28 weeks or greater) should be
managed according to standard obstetric protocols (16). In cases of fetal demise before 28
weeks, misoprosol is effective when given in doses of 200-400 mcg vaginally every 4-12 hours.
This regimen seems to be safe even for women with a prior low transverse uterine scar (26, 27)
(Level B).
Prior cesarean or uterine surgery
The use of prostaglandins in the third trimester in women with a prior cesarean delivery or major
uterine surgery is associated with an increase in uterine rupture and, therefore, should be avoided
(28) (Level C).
PROPOSED PERFORMANCE MEASURE
The percentage of cases in which the documented Bishop score prior to the initiation of cervical
ripening is <6.
REFERENCES
1. Agency for Healthcare Research and Quality. Maternal and neonatal outcomes of elective
induction of labor. AHRQ Evidence Report/Technology Assessment No. 176. Rockville
(MD): AHRQ; 2009. (Systematic review)
2. Guidelines for Perinatal Care, October 2007, American Academy of Pediatrics and the
American College of Obstetricians and Gynecologists. — 6th ed.
3. Morrison JJ, et.al. Neonatal respiratory morbidity and mode of delivery at term:
influencing of timing of elective cesarean delivery. Br J Obstet Gynaecol 1995;102:10
4. ACOG Practice Bulletin #97, August 2008, Fetal Lung Maturity
5. Bates E, Rouse D, Mann M, et al., Neonatal outcomes after demonstrated lung maturity
before 39 weeks of gestation. Obstet Gynecol 2010;116:1288.
6. Vrouenraetsm F, Roumen F, Dehing C, et al. Bishop score and risk of cesarean delivery
after induction of labor in nulliparous women. Obstet Gynecol 2005;105:690.
7. Bishop E, Pelvic scoring for elective induction. Obstet Gynecol 1964;24:266.
8. Vaknin Z, Kurzweil Y, Sherman D, Foley catheter balloon vs. locally applied
prostaglandins for cervical ripening and labor induction: a systematic review and
metaanalysis. Am J Obstet Gynecol 2010;203:418.
9. Boulvain M, Kelly A, Lohse C, Stan C, Irion O. Mechanical methods for induction of
labour. Cochrane Database of Systematic Reviews 2001, Issue 4. Art. No.: CD001233.
DOI: 10.1002/14651858.CD001233.
10. Krammer J, Williams MC, Sawai SK, O’Brien WF. Pre-induction cervical ripening: a
randomized comparison of two methods. Obstet Gynecol 1995;85:614–8.
11. Boulvain M, Stan C, Irion O. Membrane sweeping for induction of labour. Cochrane
Database of Systematic Reviews 2005, Issue 1. Art. No.: CD000451. DOI: 10.1002/
14651858.CD000451.pub2.
12. Lin M, Reid K, Treaster M, et al. Transcervical Foley catheter with and without
extraamniotic saline infusion for labor induction: a randomized controlled trial. Obstet
Gynecol 2007;110:558.
13. Heinemann J, Gillen G, Sanchez-Ramos L, Kaunitz A, Do mechanical methods of
cervical ripening increase infectious morbidity? A systematic review. Am J Obstet
Gynecol 2008;199:177.
14. Levy R, Kanengiser B, Furman B et al. A randomized trial comparing a 30-mL and an
80-mL Foley catheter balloon for preinduction cervical ripening. Am J Obstet Gynecol
2004;191:1632.
15. Pettker C, Pocock S, Smok D, et al. Transcervical Foley catheter with and without
oxytocin for cervical ripening: a randomized controlled trial. Obstet Gynecol
2008;111:1320.
16. Hofmeyr GJ, Gulmezoglu AM. Vaginal misoprostol for cervical ripening and induction
of labour. Cochrane Database of Systematic Reviews 2003, Issue 1. Art. No.: CD000941.
DOI: 10.1002/14651858.CD000941.
17. ACOG Practice Bulletin #107, August 2009, Induction of Labor
18. Alfirevic Z, Oral misoprostol for induction of labour. Cochrane Database Syst Rev 2001;
;CD001338.
19. Bernstein P. Prostaglandin E2 gel for cervical ripening and labour induction: a
multicentre placebo-controlled trial. CMAJ 1991;145:1249–54.
20. ACOG Practice Bulletin #116, November 2010, Management of Intrapartum Fetal Heart
Rate Tracings.
21. Sanchez-Ramos L, Chen AH, Kaunitz AM, Gaudier FL, Delke I. Labor induction with
intravaginal misoprostol in term premature rupture of membranes: a randomized study.
Obstet Gynecol 1997;89:909–12.
22. Wing DA, Ortiz-Omphroy G, Paul RH. A comparison of intermittent vaginal
administration of misoprostol with continuous dinoprostone for cervical ripening and
labor induction. Am J Obstet Gynecol 1997;177:612–8.
23. Lin M, Rouse D, What is a failed labor induction? Clin Obstet Gynecol 2006;49:585.
24. Rouse D, Owen J, Hauth J, Criteria for failed induction: prospective evaluation of a
standardized protocol. Obstet Gynecol 2000;96:671.
25. Simon C, Grobman W, When has an induction failed? Obstet Gynecol 2005;105:705.
26. Dickinson JE, Evans SF. The optimization of intravaginal misoprostol dosing schedules
in second-trimester pregnancy termination [published erratum appears in Am J Obstet
Gynecol 2005;193:597]. Am J Obstet Gynecol 2002;186:470–4.
27. Dickinson JE. Misoprostol for second-trimester pregnancy termination in women with a
prior cesarean delivery. Obstet Gynecol 2005;105:352–6.
28. ACOG Practice Bulletin #115, August 2010, Vaginal Birth After Previous Cesarean
Delivery
APPENDIX
Studies were reviewed and evaluated for quality according to the method outlined by the
U.S. Preventative Services Task Force
I Evidence obtained from at least one properly designed randomized controlled trial.
II–1 Evidence obtained from well–designed controlled trials without randomization.
II–2 Evidence obtained from well–designed cohort or case–control analytic studies, preferably
from more than one center or research group.
II–3 Evidence obtained from multiple time series with or without the intervention. Dramatic
results in uncontrolled experiments also could be regarded as this type of evidence.
III Opinions of respected authorities, based on clinical experience, descriptive studies, or reports
of expert committees.
Based on the highest level of evidence found in the data, recommendations are provided and
graded according to the following categories:
Level A—Recommendations are based on good and consistent scientific evidence.
Level B—Recommendations are based on limited or inconsistent scientific evidence.
Level C—Recommendations are based primarily on consensus and expert opinion.