Mechanical Methods of Cervical Ripening and Labor Induction
Drexel University, 245 North 15th Street, MS 495, New College Building, Philadelphia, Pennsylvania 19102, USA. Clinical Obstetrics and Gynecology
(Impact Factor: 1.77).
10/2006; 49(3):642-57. DOI: 10.1097/00003081-200609000-00022
This article reviews the safety and efficacy of mechanical agents for cervical ripening. Hygroscopic dilators, balloon catheters, and devices designed for cervical ripening have all been shown to be safe and effective for cervical ripening. Mechanical agents are as efficacious as other agents for cervical ripening. However, there is no method that has been conclusively shown to improve mode of delivery or perinatal outcome. The advantages of preinduction cervical ripening with mechanical devices include low cost, low incidence of systemic side effects, and low risk of uterine hyperstimulation.
Available from: Ellen Løkkegaard
- "One difference between PGs and mechanical methods for cervical ripening is that exogenous PGs frequently both ripen the cervix and induce labour, whereas mechanical agents may ripen the cervix but not lead to labour induction. Consequently, further induction with oxytocin may be required (Gelber and Sciscione 2006). "
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ABSTRACT: This randomised controlled study compared the efficacy of double-balloon catheter versus vaginal prostaglandin E2 (dinoprostone) for induction of labour. In total, 825 pregnant women with cephalic presentation and an unfavourable cervix undergoing induction for conventional indications were randomised to double-balloon or vaginal dinoprostone (3 mg) groups. There was a significantly higher failure rate for labour induction in the balloon group (relative risk: 1.25, 95% confidence interval [CI]: 1.02-1.49). Median induction time was 27.3 h in the balloon group and 29.8 h in the dinoprostone group (difference not significant). After 24 h, 55.3% had given birth in the balloon group versus 54.3% in the dinoprostone group. Additional oxytocin stimulation was used more often in the balloon (46%) compared with that in the dinoprostone (34%) (relative risk: 1.34 (95%CI 1.16 -1.54) group. Caesarean section rates and neonatal outcome were similar. Overall, the two methods for induction were comparable with regard to efficacy and safety.
Available from: Sasa Raicevic
- "Although cervical dilation is most commonly reserved for childbirth, its use has expanded to a large number of diagnostic procedures (dilation and curettage for diagnosing endometrial cancer, endometrial biopsies, evaluating the causes of infertility and hysteroscopy) and therapeutic procedures (cervical stenosis, dysfunctional uterine bleeding and dysmenorrhea, inserting intrauterine devices and draining the uterine cavity) [1-3]. Mechanical instruments, such as the Hern, Hegar, Pratt, Hanks and Denniston dilators, are used to sequentially dilate the cervix [4,5] by incrementally increasing the diameter of the inserted dilator until the dilation procedure is complete. However, these mechanical dilators require the use of appropriate force, which could permanently damage the cervical tissue and have adverse long-term effects on fertility [6-9]. "
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ABSTRACT: Cervical dilation using mechanical dilators is associated with various complications, such as uterine perforation, cervical laceration, infections and intraperitoneal hemorrhage. To achieve safe and painless cervical dilation, we constructed a new medical device to achieve confident mechanical cervical dilation: a continuous controllable balloon dilator (CCBD).
Controlled pumping of incompressible fluid into the CCBD increases the pressure and outer diameter of the CCBD, continuously dilating the cervical canal. The reliability of the CCBD was confirmed in vitro (testing for consistency and endurance, with no detected risk for breakage) and in vivo. A multi-center clinical study was conducted,with 120 pregnant women randomly assigned to one of three groups: Group I,control group, no dilation;Group II,mechanical dilation, Hegar dilator (HeD); and Group III,CCBD. The tissue material for histological evaluation was obtained from the endocervical mucosa before and after dilation using the HeD or CCBD.
The CCBD dilations were successful and had no complications in all 40 patients of Group III. The cervical tissue was markedly less damaged after CCBD dilation compared with HeD dilation (epithelium damage: 95% (HeD) vs. 45% (CCBD), P <0.001; basal membrane damage: 82.5% (HeD) vs. 27.5% (CCBD), P <0.001; stromal damage: 62.5% (HeD) vs. 37.5% (CCBD), P <0.01). Cervical hemorrhagia was observed in 90% of the patients after HeD dilation versus in 32.5% of the patients after CCBD dilation.
The CCBD should be used as a replacement for mechanical dilators to prevent uterine and cervical injury during cervical dilation.
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ABSTRACT: Aims: To compare the effectiveness of hygroscopic dilators against vaginal prostaglandins in the practice of induction of labour. Methods: Randomised trials that compared hygroscopic dilators with vaginal prostaglandins were identified from 1987- 2007. Eligibility and trial quality were assessed by selected criteria which were determined a priori. Data were extracted and analysed using RevMan 4.2 software. Overall outcomes were expressed as relative risk (95% confidence intervals). Where result heterogeneity existed, a random effects model was used. We evaluated vaginal delivery rate as the primary outcome. Secondary outcomes assessed included maternal morbidity, neonatal morbidity, and foetal heart rate (FHR) changes necessitating emergency Caesarean section (CS). Results: Five studies (991 women) comparing hygroscopic dilators with vaginal prostaglandins in primiparous women were identified. Hygroscopic dilators were less likely to achieve vaginal delivery compared to prostaglandins although this was not statistically significant (RR 0.95; 95% CI: 0.88-1.02). Hygroscopic dilators were also more likely to cause maternal morbidity (RR 1.61; 95% CI: 1.09-2.37) and neonatal morbidity (RR 2.11; 95% CI: 1.28-3.49). There was no statistical difference between the 2 groups in causing FHR changes necessitating emergency CS. Conclusions: There is no significant advantage of using hygroscopic dilators versus prostaglandins in the induction in labour when comparing vaginal delivery rates and the incidence of foetal heart rate changes requiring emergency Caesarean sections. Maternal and neonatal morbidities may be increased when using dilators for induction of labour.
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