Cervical Ripening

Aka: Cervical Ripening

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II. Definitions

  1. Cervical Ripening
    1. Changes in the Uterine Cervix, readying it to relax for active labor
    2. Cervix softens and shortens normally in late pregnancy
    3. Chemical and manual measures can augment the ripening process

III. Indications

  1. Bishop Score <5 prior to Labor Induction

IV. Medications: Prostaglandins

  1. See Cervical Ripening Agents
  2. Dinoprostone (PGE2 Gel, Cervidil, Prepidil)
    1. Available for oral, vaginal and sublingual use
  3. Misoprostol (PGE1, Cytotec)
    1. Available as vaginal preparation
  4. Adverse Effects
    1. Risk of tachysystole (>5 contractions in 10 minutes)

V. Procedures: Mechanical Methods to Apply Pressure to Endocervix

  1. See Cervical Membrane Sweeping
  2. General
    1. Mechanism: Local pressure releases Prostaglandins
    2. Risks
      1. Infection risk with Laminaria
      2. Artificial Rupture of Membranes
      3. Abruptio Placenta
      4. Cervical or uterine bleeding
  3. Hygroscopic Dilator or Osmotic Dilator (Laminaria, Lamicel)
    1. Dilator swells with absorption of local fluid
    2. Preparations
      1. Laminaria japonicum (Kelp, natural)
      2. Lamicel (synthetic)
      3. Dilapan-S Rods (synthetic)
    3. Adverse Effects
      1. Infection risk
    4. Technique: Outpatient placement of dilator in endocervix
      1. Monitor for Fetal Heart Tones continuously for 20 minutes prior to insertion
      2. Use a sterile speculum to visualize Cervix
      3. Use antiseptic to disinfect Cervix
      4. Tenaculum or ring forceps is used to stabilize Cervix
      5. Moisten dilator with sterile saline
      6. Successive dilators placed until endocervix full (1-2 Laminaria, 3-5 Dilapan-S)
      7. Sterile gauze pad applied inside vagina to hold dilator in place
      8. Record the number of dilators used within the medical record
      9. No Fetal Heart Rate monitoring needed after placement
      10. Remove gauze and Dilapan-S Rods after 12 hours and Laminaria after 12 to 24 hours
  4. Single Balloon Catheter Dilation (e.g. 16 french Foley Catheter)
    1. Technique
      1. Catheter placed in endocervix during bimanual exam or with speculum
      2. Insert catheter tip gently until it fully traverses Cervix into uterine cavity (balloon completely in Cervix)
      3. Catheter tip inflated with 30 cc sterile water
      4. Traction applied to catheter
      5. Start Induction when catheter is extruded
      6. Remove catheter at 12 hours if not yet extruded
    2. Adjuncts
      1. Weight end of catheter
      2. Tug on catheter 2-4 times per hour
      3. Sterile saline infusion
      4. Prostaglandin gel
    3. Safety
      1. Does not appear to predispose to subsequent PTL
      2. Sciscione (2003) Am J Obstet Gynecol 190:751-4 [PubMed]
  5. Double Balloon Catheter Dilation
    1. Similar to single balloon technique
    2. Inflate uterine balloon with 40 ml saline and then retract until balloon lodges against internal os
    3. Confirm vaginal balloon is palpable or visualized outside external os
      1. Remove speculum (if used) and inflate the vaginal balloon with 20 ml saline
    4. Each balloon (uterine and vaginal) may each be further inflated with up to 80 ml saline
    5. Traction is not required with a double balloon setup
  6. References
    1. de Vaan (2019) Cochrane Database Syst Rev (10): CD001233

VI. Management: Non-Pharmacologic Methods

  1. Breast stimulation
    1. See Oxytocin Challenge Test
    2. Limited and variable evidence in small trials (NNT 8)
    3. Theoretical benefit
      1. Breast stimulation stimulates Oxytocin release
      2. Fetal Heart Rate response similar to OCT
    4. Technique
      1. Gentle bilateral Breast Massage
      2. Perform for 15 to 20 minutes, three times daily starting at 38 weeks
    5. References
      1. Singh (2014) Biomed Res Int 2014:695037 +PMID:25525601 [PubMed]
  2. Sexual Intercourse
    1. Benefits in Cervical Ripening or induction are unclear (no significant evidence)
    2. Theoretical benefit
      1. Female orgasm induces uterine contraction
      2. Semen contain Prostaglandins
  3. Exercise
    1. Walking 30 minutes per day at least 3 times per week may be effective for induction after 38 weeks (small study)
    2. Pereira (2020) J Matern Fetal Neonat Med 35(4):775-9 +PMID: 32223479 [PubMed]

VII. Protocols: Alternative/Herbals

  1. General
    1. Used by some nurse-midwives in United States
    2. Anecdotal use in some cultures as long tradition
    3. No current rigorous studies on safety and efficacy
  2. Herbals historically used for Cervical Ripening
    1. Evening Primrose Oil
    2. Black Haw
    3. Black Cohosh
    4. Blue Cohosh
    5. Red raspberry leaves
  3. References
    1. McFarlin (1999) J Nurse Midwifery 44:205-16 [PubMed]

VIII. Protocols: Disproved Methods that are not recommended

  1. Castor Oil
  2. Hot baths
  3. Enemas
  4. Acupuncture (or Acupressure)
    1. Proposed for Oxytocin and Prostaglandin release
    2. No benefit in studies
    3. Smith (2017) Cochrane Database Syst Rev (10):CD002962 +PMID:29036756 [PubMed]

IX. References

  1. Adair (2000) Clin Obstet Gynecol 43:447-54 [PubMed]
  2. Tenore (2003) Am Fam Physician 67(10):2123-8 [PubMed]
  3. Wheeler (2022) Am Fam Physician 105(2): 177-86 [PubMed]

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