Cervical ripening and the bishop score

Cervical ripening is the preparation of the cervix for labour and delivery. The Bishop score is the commonest used methodology to assess it. For more like this visit my page on YouTube https://www.youtube.com/@mudiagaakpoghene2243

1. CERVICAL RIPENING AND THE BISHOP SCORE BY Dr Moses Akpoghene Medical Officer Obstetrics and Gynaecology department Federal Medical centre Jalingo

2. OUTLINE Introduction The Uterine cervix Ripening of the cervix Pathophysiology of cervical ripening Evaluation of cervical ripening Bishop scoring system Initiation of cervical ripening Contra indication to cervical ripening Summary References

3. INTRODUCTION Induction of labor is common in obstetric practice. According to literature, the rate varies from 9.5 to 33.7 percent of all pregnancies annually. In the absence of a ripe or favorable cervix, a successful vaginal birth is less likely. Therefore , cervical ripening or preparedness for induction should be assessed before a regimen is selected. Assessment is accomplished by calculating a Bishop score. When the Bishop score is less than 6, it is recommended that a cervical ripening agent be used before labor induction.

4. In pregnancy, the uterine cervix serves 2 major functions. First , it retains its physical integrity by remaining firm during pregnancy as the uterus dramatically enlarges. This physical integrity is critical so that the developing fetus can remain in the uterus until the appropriate time for delivery. UTERINE CERVIX

5. UTERINE CERVIX Second , in preparation for labor and delivery, the cervix softens and becomes more distensible, a process called cervical ripening. These chemical and physical changes are required for cervical dilation, labor and delivery of a fetus.

6. UTERINE CERVIX The human cervix consists mainly of extracellular connective tissue. The predominant molecules of this extracellular matrix are type 1 and type 3 collagen, with a small amount of type 4 collagen at the basement membrane.

7. UTERINE CERVIX Intercalated among the collagen molecules are glycosaminoglycans and proteoglycans, predominantly dermatan sulfate, hyaluronic acid, and heparin sulfate. Fibronectin and elastin also run among the collagen fibers. The highest ratio of elastin to collagen is at the internal os . Both elastin and smooth muscle decrease from the internal to the external os of the cervix.

8. RIPENING OF THE CERVIX Cervical ripening refers to the softening of the cervix that typically begins prior to the onset of labor contractions and is necessary for cervical dilation and the passage of the fetus. Cervical ripening results from a series of complex biochemical processes that ends with rearrangement and realignment of the collagen molecules.

9. RIPENING OF THE CERVIX The cervix thins , softens, relaxes and dilates in response to uterine contractions, allowing the cervix to easily pass over the presenting fetal part during labor .

10. Associated with cervical ripening is an increase in the enzyme cyclooxygenase-2, leading to a local increase of prostaglandin E2 (PGE2) in the cervix. Prostaglandin F2-alpha is involved in the process via its ability to stimulate an increase in glycosaminoglycans . PHYSIOLOGY OF CERVICAL RIPENING

11. Prostaglandins lead to dilation of small vessels in the cervix, increase in collagen degradation, increase in hyaluronic acid, increase in chemotaxis for leukocytes, which causes increased collagen degradation and increase in stimulation of interleukin (IL)–8 release. IL-8 can lead to neutrophil chemotaxis , which is associated with collagenase activity and cervical ripening. PHYSIOLOGY OF CERVICAL RIPENING

12. PHYSIOLOGY OF CERVICAL RIPENING This increased hyaluronic acid content in the cervix leads to an increase in water molecules that intercalate among the collagen fibers causing decreased collagen fiber alignment, decreased collagen fiber strength and diminished tensile strength of the extracellular cervical matrix.

13. An associated change with the cervical ripening process is an increase in cervical decorin ( dermatan sulfate proteoglycan 2), leading to collagen fiber separation. This causes decrease in cervical firmness. A ll these occur with decrease in chondroitin sulfate and together lead to softening of the cervix ( ie , ripening ). PHYSIOLOGY OF CERVICAL RIPENING

14. Contractions cause reorientation on cervix Under the effect of myometrial contractions, the cervix passively dilates and is pulled over the presenting fetal part. Evidence also indicates that the elastin component of the cervix behaves in a ratchetlike manner so that dilation is maintained following the contraction .

15. EVALUATION OF CERVICAL RIPENING A variety of techniques have been developed to quantify cervical ripening in order to predict the timing of labor and delivery The most commonly used methodology to evaluate cervical ripening is the Bishop score because it is simple and has the most predictive value. Other methods that have been described in the literature, generally for gauging the risk of preterm labor, include ultrasound assessment of the cervix and detection of fetal fibronectin in cervicovaginal secretions .

16. In the 1964 article "Pelvic Scoring for Elective Induction," obstetrician Edward Bishop described his method to determine whether a doctor should induce labor in a pregnant woman . In his earlier publication (1955), Bishop argued that elective induction of labor is most appropriate for women who have previously given birth, with a cervical dilation of at least three centimeters, and fetuses that have descended low in the womb.

17. Bishop spends the last part of "Pelvic Scoring for Elective Induction" explaining his Bishop Score, the pelvic scoring system he devised to judge whether or not a pregnant woman and her fetus are biologically ready to enter into labor. The scoring system consists of five pelvic measurements, and the total of all five scores determines whether or not a pregnant woman can be safely induced. The first three measurements have scores ranging from zero to three, while the last two measurements have scores ranging from zero to two. In total, the highest score is thirteen, with higher scores indicating that the woman can be safely induced.

18. DILATATION The first and most important element of the Bishop score i s dilatation. Dilatation is the distance the cervix is opened measured in centimeters (cm)

19. EFFACEMENT The second measurement is of the effacement, or thinning, of the cervix. It is reported as a percentage from zero percent (normal length cervix of 3cm) to 100% or complete (paper thin cervix). Points are given from 0 to a maximum of 3 points for a cervix effaced to 80 % or greater .

20. STATION The third measurement is of the distance between the fetus's head and the woman's pelvis (station). Station is the position of the baby's head relative to the ischial spines. Points are given from 0 to a maximum of 3 points for a station of 1 + or 2+. 

21. CONSISTENCY The fourth measurement is of the consistency of the cervix . This is texture of the cervix on examination. Firm : The cervix feels hard and rubbery . Medium: The cervix feels compressible but not soft Soft : The cervix feels mushy In primigravid women, the cervix is typically tougher and resistant to stretching and with subsequent vaginal deliveries, the cervix becomes less rigid and allows for easier dilation at term.

22. POSITION The final measurement of the Bishop Score is of the alignment between the cervix and the birth canal. The position of the cervix relative to the fetal head and maternal pelvis

23. Bishop applied the Bishop Score to five hundred pregnant women who later had natural, spontaneous births without being induced. He found that the average duration of pregnancy, meaning the period of time between the scoring examination and natural delivery of an infant, was directly related to the Bishop Score.

24. INTERPRETING THE BISHOP SCORE

25. The Bishop score has been modified severally since then. One of such is the replacement of effacement with cervical length in cm, with scores as follows: 0 for > 4 cm, 1 for 3-4 cm, 2 for 1-2 cm, 3 for <1 cm . Cervical length may be easier and more accurate to measure and have less inter-examiner variability.

26. OTHER MODIFICATIONS Another modification for the Bishop's score is the modifiers: One point is added to the total score for: 1. Existence of pre- eclampsia 2. Each previous vaginal delivery One point is subtracted from the total score for: 1. Postdate/post-term pregnancy 2. Nulliparity (no previous vaginal deliveries) 3. PPROM; preterm premature ( prelabor ) rupture of membranes

27. INITIATION OF CERVICAL RIPENING A variety of methods have been developed to induce cervical ripening in the preparation of the cervix for labor and delivery . Pharmacological methods: including prostaglandins, low-dose oxytocin infusion, Mifepristone, Relaxin . Non pharmacological methods: Balloon catheter, membrane stripping, sexual intercourse etc.

28. PHARMACOLOGIC CERVICAL RIPENING PROSTAGLANDINS Prostaglandins act on the cervix to enable ripening by a number of different mechanisms. They alter the extracellular ground substance of the cervix, and PGE2 increases the activity of collagenase in the cervix . They cause an increase in elastase , glycosaminoglycan , dermatan sulfate, and hyaluronic acid levels in the cervix . Finally, prostaglandins allow for an increase in intracellular calcium levels, causing contraction of myometrial muscle.

29. PHARMACOLOGIC CERVICAL RIPENING PROSTAGLANDINS Risks associated with the use of prostaglandins include Uterine hyperstimulation Maternal side effects such as nausea, vomiting , diarrhea , and fever. Currently , two prostaglandin analogs are available for the purpose of cervical ripening, dinoprostone gel ( Prepidil ) and dinoprostone inserts ( Cervidil ).

30. PROSTAGLANDINS Cochrane reviewers examined 52 well-designed studies using prostaglandins for cervical ripening or labor induction . They compared with placebo. Results showed that the use of vaginal prostaglandins increased the likelihood that a vaginal delivery would occur within 24 hours. With comparable caesarean section rates. The only drawback appears to be an increased rate of uterine hyperstimulation and accompanying FHR changes. PHARMACOLOGIC CERVICAL RIPENING

31. PHARMACOLOGIC CERVICAL RIPENING MISOPROSTOL Misoprostol ( Cytotec ) is a synthetic PGE1 analog that has been found to be a safe and inexpensive agent for cer vical ripening, although it is not labeled by NAFDAC for that purpose . Clinical trials indicate that the optimal dose and dosing interval is 25 mcg intravaginally every four to six hours.

32. PHARMACOLOGIC CERVICAL RIPENING MISOPROSTOL Higher doses or shorter dosing intervals are associated with a higher incidence of side effects, especially hyperstimulation syndrome ( tachysystole and hypersystole ) Finally , uterine rupture in women with previous cesarean section is also a possible complication, limiting its use to women who do not have a uterine scar.

33. PHARMACOLOGIC CERVICAL RIPENING MISOPROSTOL The Cochrane reviewers concluded that use of misoprostol resulted in an overall lower incidence of cesarean section. In addition, there appears to be a higher incidence of vaginal delivery within 24 hours of application and a reduced need for oxytocin augmentation. The risks of hyperstimulation and uterine rupture are also present here.

34. MIFEPRISTONE Mifepristone is an antiprogesterone agent. Progesterone inhibits contractions of the uterus, while mifepristone counteracts this action . A RCT has shown that women treated with mifepristone are more likely to have a favorable cervix and likely to deliver within 48 to 96 hours and less likely to undergo cesarean section (compared to placebos). However, little information is available about fetal outcomes and maternal side effects; thus, there is insufficient information to support the use of mifepristone for cervical ripening PHARMACOLOGIC CERVICAL RIPENING

35. Low dose oxytocin In this method, a low-dose oxytocin infusion is performed, with an increase in dose from 1 to 4 mU /min. Ferguson et al showed this method to be comparable to intravaginal misoprostol for cervical priming. Because of the ease of turning off the oxytocin infusion, they suggested that this method may have a preferential role in high-risk patients whose fetuses are at increased risk for intolerance of labor. PHARMACOLOGIC CERVICAL RIPENING

36. RELAXIN The hormone relaxin is thought to promote cervical ripening . Cochrane reviewers evaluated results of four studies involving 267 women and concluded that there is insufficient support for the use of relaxin . Thus further trials are needed. PHARMACOLOGIC CERVICAL RIPENING

37. Stripping of the Membranes Stripping of the membranes causes an increase in the activity of phospholipase A2 and prostaglandin F2 (PGF2) as well as causing mechanical dilation of the cervix, which releases prostaglandins. The membranes are stripped by inserting the examining finger through the internal cervical os and moving it in a circular direction to detach the inferior pole of the membranes from the lower uterine segment. NON PHARMACOLOGIC CERVICAL RIPENING

38. Stripping of the Membranes Literature showed that stripping of the membranes alone does not seem to produce clinically important benefits, but when used as an adjunct appears to be associ ated with a lower mean dose of oxytocin needed and an increased rate of normal vaginal deliveries. NON PHARMACOLOGIC CERVICAL RIPENING

39. Balloon dilators Balloon devices provide mechanical pressure directly on the cervix as the balloon is filled. A Foley catheter (26 Fr ) or specifically designed balloon devices can be used . NON PHARMACOLOGIC CERVICAL RIPENING

40. The catheter is placed in the uterus, and the balloon is filled. Direct pressure is then applied to the lower segment of the uterus and the cervix. This direct pressure causes stress in the lower uterine segment and probably the local production of prostaglandins . In some studies, the catheter is combined with a saline solution as an extra-amniotic infusion . NON PHARMACOLOGIC CERVICAL RIPENING

41. Several RCTs compared the use of a balloon device with administration of an extra-amniotic saline infusion, laminaria, or prostaglandin E2 (PGE2). Results from these trials indicate that each of these methods is effective for cervical ripening and each has comparable cesarean-section delivery rates in women with an unfavorable cervix . A meta-analysis involving 27 studies and 3532 patients found that no difference between Foley balloon and PGE2 use in cesarean delivery rate. Further subgroup analysis suggested that Foley balloon in combination with oxytocin and EASI may indeed have a higher vaginal delivery rate and lower rate of tachysystole . NON PHARMACOLOGIC CERVICAL RIPENING

42. The risks associated with balloon dilators as other mechanical methods include Infection ( endometritis and neonatal sepsis), Bleeding, Membrane rupture, and Placental disruption. NON PHARMACOLOGIC CERVICAL RIPENING

43. HYGROSCOPIC DILATORS Hygroscopic dilators absorb endocervical and local tissue fluids , causing the device to expand within the endocervix and providing controlled mechanical pressure. The products available include natural osmotic dilators (e.g., Laminaria japonicum ) and synthetic osmotic dilators (e.g ., Lamicel ). The main advantages of using hygroscopic dilators include outpatient placement and no need for FHR-monitoring. NON PHARMACOLOGIC CERVICAL RIPENING

44. SEXUAL INTERCOURSE Sexual intercourse is commonly recommended for promoting labor initiation. Sexual relations usually involve Stimulation of the breasts and nipples, which can promote the release of oxytocin . With penetration, the lower uterine segment is stimulated. This stimulation results in a local release of prostaglandins. Female orgasms have been shown to include uterine contractions, and Human semen contains prostaglandins , which are responsible for cervical ripening. Only one study of 28 women resulted in minimally useful data , so the role of sexual intercourse as a method of promoting labor initiation remains uncertain NON PHARMACOLOGIC CERVICAL RIPENING

45. Others that have been suggested but not supported in literature include Castor oil, hot baths and enemas Acupuncture and transcutaneous nerve stimulation Herbal remedies such as Raspberry leaves and Primrose oil. NON PHARMACOLOGIC CERVICAL RIPENING

46. Contraindications to cervical ripening Contraindications to cervical ripening include, but are not limited to, the following: Active herpes Fetal malpresentation Nonreassuring fetal surveillance Regular contractions Unexplained vaginal bleeding Placenta previa Vasa previa Prior uterine myomectomy involving the endometrial cavity or classical cesarean delivery A relative contraindication to cervical ripening is ruptured membranes.

47. In Summary Induction of cervical ripening is critical to successful induction of labor in a pregnant patient whose cervix has not gone through the ripening process. Cervical ripening allows the uterine contractions to effectively dilate the cervix. The Bishop score is the is simple and has the most predictive value thus it’s the most commonly used methodology. There are pharmacological and non pharmacological methods of inducing cervical ripening with varying success rates but most popular are Prostaglandins, Misoprostol and Balloon dilators.

48. REFERENCES Abboud , Carolina J., "“Pelvic Scoring for Elective Induction” (1964), by Edward Bishop". Embryo Project Encyclopedia (2017-02-23). ISSN: 1940-5030 http://embryo.asu.edu/handle/10776/11426. American College of Obstetricians and Gynecologists (1999) Induction of labor. Practice bulletin no. 10. Washington, D.C.: ACOG. Bishop EH (1964) Pelvic scoring for elective induction.Obstet Gynecol .;24:266-8 . Dutta DC (2001) Text Book of Obstetrics. 6ed. New Central Book Agency. Goldberg AB, Greenberg MB, Darney PD (2001) Misoprostol and pregnancy. N Engl J Med;344:38-47 . Goldman JB, Wigton TR (1999) A randomized comparison of extra-amniotic saline infusion and intracervical dinoprostone gel for cervical ripening. Obstet Gynecol;93:271-4 . Cervical ripening. Available at https ://emedicine.medscape.com/article/263311-overview Norwitz E, Robinson J, Repke J. (2002)Labor and delivery. In: Gabbe SG, Niebyl JR, Simpson JL, eds. Obstetrics: normal and problem pregnancies. 4th ed. New York: Churchill Livingstone:353-94. Tenore JL. (2003) Methods for Cervical Ripening and Induction of Labor . American Family Physician. 67 (10):

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