2024 Volume 12 Issue 4 Pages 69-72
Aim: We examined the difference in pain levels between using the controlled-release dinoprostone vaginal delivery system (PROPESS) and mechanical methods.
Methods: Between December 2023 and January 2024, 13 nulliparous women used PROPESS and 13 nulliparous women used mechanical methods (as control) for cervical ripening at 41 weeks of gestation. After the selected insertion methods were completed, the patients were asked about their pain levels during the insertion, with the pain scored on a ten-point Numeric Rating Scale (NRS). In addition, successful cervical ripening was defined when the Bishop score was >6 or the patient delivered vaginally by the next day following insertion of PROPESS only or mechanical cervical dilation only.
Results: The average NRS score after PROPESS insertion was 2.6±2, which was significantly lower than that after mechanical methods (5.7±3, P<0.01). There was no significant difference in the success rate of cervical ripening between mechanical method and PROPESS insertion groups (38 vs. 31%, respectively, P=0.68).
Conclusion: The potential benefit of PROPESS being pain-free was observed in women requiring cervical ripening.
In 2020 in Japan, the controlled-release dinoprostone vaginal delivery system (PROPESS, Ferring Pharmaceuticals, Saint-Prex, Switzerland) was approved for cervical ripening of pregnant women prior to labor induction at ≥37 weeks of gestation.1) To date, there have been some studies assessing the effectiveness of PROPESS compared with mechanical methods for cervical ripening.2,3) The researches indicates that both options are similarly effective, and combining them can be successful. Although the studies mentioned the potential benefit of PROPESS being pain-free,2,3) there has been no evaluation or discussion of pain levels or patient experience in comparison with mechanical methods.
Pain is an important aspect to consider in clinical practice. Therefore, in this study, we examined the difference in pain levels between using PROPESS and mechanical methods.
The current study was granted approval by the Ethics Committee of the Japanese Red Cross Katsushika Maternity Hospital (K23-10), and all participants gave informed consent prior to their inclusion.
This prospective cohort study was conducted at our institute, one of the main perinatal centers in Tokyo, Japan between October and December 2023. In our institute, induction of labor is performed at 41 weeks of gestation to prevent post-term pregnancy. Clinical data on maternal characteristics and obstetric outcomes were obtained from hospital records. The criteria for inclusion in this study were as follows: nulliparity, singleton pregnancy, cephalic presentation, gestational age of 41 weeks, and a Bishop score at the beginning of induction equal to or less than 4. The exclusion criteria in this study were those with perinatal complications such as hypertensive disorders and oligohydramnios.
Between December 2023 and January 2024, 13 women used PROPESS and 13 women used mechanical methods (as control) for cervical ripening at 41 weeks of gestation.
In our institute during the study period, upon admission for induction of labor, internal examinations were performed to evaluate the Bishop score of each patient. When a Bishop Score ≤4 was observed, PROPESS or mechanical methods (=insertion of laminaria tents or their synthetic equivalent such as Dilapan in the cervical canal)4) were freely selected as suitable intervention options freely. For insertion of the PROPESS, PROPESS was held between the second and third fingers wearing medical gloves, inserted into the posterior vaginal canal, and retained in the vaginal canal. On the other hand, for insertion of the Dilapan, a vaginal speculum was inserted and the vaginal canal was washed with a saline solution. The cervix was then held with a single hook forceps, and one to 3 pieces of Dilapan pinched with the forceps were inserted into the cervix canal slowly, and held in the place with a gauze moistened with saline solution. In this study, the number of implementers was limited to one in order to eliminate differences between implementers, and the number of Dilapan insertions was limited to within 3 pieces and avoided attempt force insertion. After the selected insertion methods were completed, the patients were asked about their pain levels during the insertion, with the pain scored on a ten-point numerical pain-rating scale (=Numeric Rating Scale, NRS). NRS is a simple and commonly used tool for measuring pain intensity on a scale from 0 to 10. A score of zero represents “no pain” and 10 represents the “most intense pain possible”.5) Patients are asked to rate their level of pain by choosing a number on the scale that best represents their pain intensity. The interviews about pain were conducted during fetal heart rate monitoring approximately 20–40 minutes after the insertion, and the patients were asked to rate the pain they felt the longest during the insertion rather than instantaneous pain.
Successful cervical ripening was defined when the Bishop score was >6 or the patient delivered vaginally by the next day following insertion of PROPESS only or mechanical cervical dilation only. In addition, we examined Bishop score at the removal, cesarean delivery rate, and number of days from the start of induction to delivery.
Before discharge, we asked about the pain level at the most painful time during the active phase of labor with the pain score.
The effectiveness of PROPESS and mechanical methods was assessed by the change in Bishop score, cesarean delivery rate, and days to delivery. While, the long-term psychological impact of the pain was assessed by the Edinburgh Postnatal Depression Scale (EPDS) and the Japanese version of Mother-to-Infant Bonding Scale (MIBS-J) at the 1-month postpartum checkup.6,7,8) In the EPDS, scores of 9 points or more were regarded as ‘positive screening’ according to the results of previous observations in Japan by Okano et al.6,7) MIBS-J has been demonstrated to be acceptable reliability and reasonable construct validity concerning affection and anger/rejection in Japanese postpartum women.8) If a score is higher than 3, there is a possibility that the mother will have problems regarding feelings for her baby.
Data are presented as numbers (percentages) or mean±standard deviation (SD). Statistical analyses were performed with SAS version 8.02 (SAS Institute, Cary, NC, USA). Cases were compared by Student’s t-test for continuous variables or the chi-square test or Fisher’s exact test for categorical variables. Statistical significance was set as P<0.05.
Table 1 shows the clinical characteristics of the women in the PROPESS and mechanical method groups in this study. There were no significant differences in any variables between the 2 groups.
| Mechanical Methods group | PROPESS group | P-value | |
|---|---|---|---|
| Total number | 13 | 13 | |
| Maternal age (y) | 32±4 | 32±4 | 0.86 |
| Maternal height (cm) | 158±6 | 157±7 | 0.54 |
| Maternal BMI at admission | 27.5±2.1 | 28.0±2.4 | 0.48 |
| Bishop score at admission | 3.4±0.6 | 3.6±0.5 | 0.34 |
| Neonatal birth weight (g) | 3,268±459 | 3,248±486 | 0.68 |
PROPESS, controlled-release dinoprostone vaginal delivery system.
Data are presented as numbers (percentages) or mean±standard deviation (SD).
The average NRS score at PROPESS insertion was 2.6±2, which was significantly lower than that during mechanical methods (5.7±3, P<0.01). In this study, 3 pregnant women in the mechanical methods group were reported to complain of fear of cervical ripening in the next morning.
In one case in the PROPESS group, PROPESS was removed because of onset of labor pains. There was no significant difference in the success rate of cervical ripening between the PROPESS insertion and mechanical methods groups [31 (4/13) vs. 38% (5/13), respectively, P=0.68]. There was no significant difference in the averaged Bishop score at the removal between the PROPESS and mechanical methods groups (5.4±3 vs. 5.7±3, respectively, P=0.34). Finally, the cesarean delivery rate was also not different between the two groups [23 (3/13) vs. 23% (3/13), respectively, P=1]. No significant difference in the number of days from the start of induction to delivery between the PROPESS and mechanical methods groups (3.1±1 vs. 3.4±1, respectively, P=0.44).
In addition, there was no significant difference in the average NRS score at the most painful time during the active phase of labor between the PROPESS and mechanical methods groups (9.0±3 vs. 8.7±3, respectively, P=0.43).
There were no significant differences in the rate of score ≥9 of the EPDS and ≥3 of the MIBS-J indicating problems with maternal feelings between the PROPESS and mechanical methods groups [the EPDS: 8 (1/13) vs. 15% (2/13), respectively, P=0.54; the MIBS-J: 0 (0/13) vs. 8% (1/13), respectively, P=0.31].
Based on the current results, the potential pain-free benefit of PROPESS compared with mechanical methods was quantitatively proven. To date, both options have been observed to be similarly effective in various pregnant women requiring labor induction at term.9,10) The current results also support these previous observations.9,10) Therefore, we may recommend the use of PROPESS more actively for pregnant women with cervical ripening deficiency.
Valid and reliable assessment of pain during cervical ripening maneuvers will be essential for minimizing the emotional trauma of childbirth. Emotional trauma during delivery has been reported to impact communication, conflict, emotions, and bonding children, leading to the development of postpartum depression and/or bonding disorders.11,12,13,14,15) Therefore, the choice of a painless method for cervical ripening may lead to a more comfortable delivery and better postpartum condition for patients.16) Although the nature of pain makes objective measurement impossible, it may be able to be reliably assessed with one-dimensional tools such as the numeric rating scale.
Although there was a significant difference in pain due to the use of PROPESS and mechanical methods in pregnant women requiring cervical ripening, we cannot deny the presence of serious bias and/or limitations in this study. The small number of cases is the primary bias of this study. This is because PROPESS has not been available in Japan for a long time. We also cannot deny the existence of bias in the background of the subjects, as they were given a free choice of cervical ripening method. This is because mechanical cervical dilatation is a procedure covered by insurance, whereas PROPESS incurs out-of-pocket costs of more than US＄150. In addition, the current clinical trial was stopped prematurely because a clear and significant difference was observed during the study. However, pain during delivery is a very important problem in pregnant women, as mentioned above, so a further large-scale study may be needed to determine the difference more clearly.
At last, while we fully understand that it is better to increase the number of subjects as a clinical trial, we have decided not to continue further studies. This is because the difference in pain levels between the two groups was clear, and in the instrumental dilation group, in particular, having pregnant women easily self-evaluate their pain immediately after the procedure could be traumatic for them and have a significant impact on the subsequent course of delivery. In this study, 3 pregnant women were reported to complain of fear of cervical ripening in the next morning. The midwives at our hospital were fully concerned about this point, and more time was needed after the pain assessment to listen and sympathize with the pregnant woman’s feelings than is usually necessary during normal delivery management. Under their care, the subjects continued to induce delivery successfully, and although we did not observe any impact on delivery prognosis or postpartum bonding, they made us aware that instrumental dilation was causing obvious pain to the pregnant women and had the potential to lead to trauma for them.
Overall, PROPESS may be one of the safe and effective methods of relieving pain during delivery;2,3,17) however, it is associated with some side effects such as transient uterine tachysystole and hyperstimulation.10,18) It is undeniable that these can lead to different kinds of pain-related discomfort for pregnant women as well as stress loaded on the fetus. Although both patients and physicians should be aware of the associated risks, PROPESS may be viewed as one of the useful options for cervical ripening.
Although the current study may be small, the cervical ripening effect of PROPESS was not significantly different from that of mechanical methods. In addition, the potential benefit of PROPESS being pain-free was observed in women requiring cervical ripening.
None.
