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ORIGINAL ARTICLE
Year : 2020  |  Volume : 33  |  Issue : 2  |  Page : 464-468

Early versus delayed amniotomy after vaginal misoprostol for labor induction in nulliparous women


1 Department of Obstetrics and Gynecology, Faculty of Medicine, Menoufia University, Menoufia, Egypt
2 Department of Obstetrics and Gynecology, Quesna Central Hospital, Quesna, Egypt

Date of Submission09-Apr-2019
Date of Decision24-Apr-2019
Date of Acceptance27-Apr-2019
Date of Web Publication27-Jun-2020

Correspondence Address:
Hager A. A. Youssif
Atef Alsadat Street, Shebin Alkom
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/mmj.mmj_151_19

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  Abstract 


Objectives
To compare between the effectiveness and safety of early versus delayed amniotomy after vaginal misoprostol for the induction of labor.
Background
The aim of successful induction of labor is to achieve vaginal delivery when continuation of pregnancy presents a threat to the life or well-being of the mother or fetus. The process of induction of labor should only be considered when vaginal delivery is felt to be the appropriate route of delivery.
Patients and methods
A randomized, clinical trial that included 80 nulliparous women with medical or obstetric indication for labor induction. They were randomly assigned into two equal groups, the first group for early amniotomy and the second group for late amniotomy after use of vaginal misoprostol. Data were collected and tabulated.
Results
There was significant difference in the duration of labor between the two groups of early and late amniotomy with aP value of 0.000.There was also no significant difference in the mode of delivery with aP value equal to 0.197.
Conclusion
In well-selected cases, vaginal misoprostol followed by early intervention with amniotomy for labor induction appears to be associated with higher successful vaginal delivery rate, shorter induction-delivery interval, and better neonatal outcome over standard care.

Keywords: amniotomy, labor induction, vaginal misoprostol


How to cite this article:
Shabbana A, Alhalabi A, Elkhouly N, El-Sibai M, Youssif HA. Early versus delayed amniotomy after vaginal misoprostol for labor induction in nulliparous women. Menoufia Med J 2020;33:464-8

How to cite this URL:
Shabbana A, Alhalabi A, Elkhouly N, El-Sibai M, Youssif HA. Early versus delayed amniotomy after vaginal misoprostol for labor induction in nulliparous women. Menoufia Med J [serial online] 2020 [cited 2020 Jul 16];33:464-8. Available from: http://www.mmj.eg.net/text.asp?2020/33/2/464/287747




  Introduction Top


The process of induction of labor should only be considered when vaginal delivery is felt to be the appropriate route of delivery[1]. The objective of labor management is to end by having healthy babies to healthy mothers with the least adverse effects[2]. This aim is reached by close monitoring of the mother and fetus during labor with proper interventions when necessary. One of these interventions performed in labor management is amniotomy[3] or intentional artificial rupture of the amniotic membranes during labor is one of the most common interventions in modern obstetric and midwifery practice. It was introduced in 1756 by Thomas Denman an English obstetrician[4]. He acknowledged that amniotomy might be needed in order to induce or shorten labor[5]. Since then the importance of amniotomy as a procedure has varied over time[6].

Amniotomy may be particularly important for women in developing countries as prolonged labor can be a leading cause of maternal morbidity and contributes significantly to half a million women who die annually as a result of childbirth due to hemorrhage and infection, which are strongly connected with long labors[7],[8].

Despite the many benefits of amniotomy there are other risks associated with this procedure including umbilical cord prolapse or compression, maternal or neonatal infection, fetal heart rate decelerations, bleeding due to placenta previa or low-lying placenta, and possible fetal injury[9].

Amniotomy can be done early in the active phase of labor. Labor is considered in active phase when the cervical dilation is 4 cm and above[10], but the effectiveness of this procedure in enhancing labor has not been proven[11], so it remains a subject for debate and further research.

Use of misoprostol as a ripening agent for induction of labor combined with amniotomy decrease the incidence of cesarean section, increase the incidence of vaginal delivery within 24 h of administration, and reduced the need for oxytocin augmentation[12]. Application of misoprostol vaginally gives more rapid delivery with less hyperstimulation and tachysystole as compared with oral application[13]. The aim of this study is to compare between the effectiveness and safety of early versus delayed amniotomy after vaginal misoprostol for the induction of labor.


  Patients and Methods Top


This randomized trial was conducted at the Department of Obstetrics and Gynecology at Menoufia University Hospitals and Quesna Central Hospital from the beginning of November 2017 to August 2018 after obtaining their approval. The study protocol was approved by the Medical Ethics Committee of Faculty of Medicine, Menoufia University. It included 80 nulliparous pregnant women at term (≥36 weeks) admitted to the hospital for induction of labor. All women were informed about the nature of the study and the forms of treatment they would receive and they signed an informed consent before starting the study. The hospital institutional board review acceptance was obtained before starting the study.

Inclusion criteria were pregnant women at 36 weeks gestation or more, nullipara, singleton fetus, cephalic presentation with common medical reasons for induction include intrauterine fetal growth restriction, postterm pregnancy, and preeclampsia.

Exclusion criteria: macrosomic babies (estimated fetal weight) of more than 4000 g, previous uterine scars, prelabor premature rupture of fetal membranes, and polyhydramnios. Pregnant women attending the antenatal care clinic and meeting the inclusion criteria were randomly assigned into two equal groups.

Group A (early amniotomy): early amniotomy was performed in the early active phase of labor for the participant of the first group at 3 cm cervical dilatation with Kocher's forceps using the standard method of amniotomy provided the head is well applied to the cervix.

And group B (late amniotomy): late amniotomy was performed for the participant of the second group at 7 cm cervical dilatation.

Pregnant women attending the antenatal care clinic and meeting the inclusion criteria who had clinical examination after full history taking and were evaluated by obstetric ultrasonography were then assigned randomly to have either early or late amniotomy. Patients were assigned to each group by means of computer-generated randomization tables and their allocation were kept in consecutively numbered, sealed, and opaque envelopes till the time of intervention.

Misoprostol (1/8 misotac 200 mg tablet; Sigma Pharmaceutical Company, Quweisna, Menofia Governorate, Egypt) as 25 μg of misoprostol was administrated vaginally. The administration of misoprostol was repeated every 6 h until three or more uterine contractions of 40 s duration occur over 10 min, or when a maximum of four doses (i.e. 100 μg) is reached[14]. The process of labor was monitored by using a partogram for continuous observation of the mother and fetus and different actions taken according to it. If there was no active labor 6 h after administration of the last dose of misoprostol, failed induction was documented and a cesarean section was performed.

The primary outcome was the frequency of successful induction, defined as vaginal delivery within 24 h from the beginning of induction.

Secondary outcomes were induction-delivery interval, duration of labor, amniotomy-delivery interval, number of misoprostol doses administration, and the need for augmentation of labor by oxytocin and perinatal outcomes included cord prolapsed, abnormal fetal heart rate changes during labor.

Successful induction of labor will be considered when each patient has vaginal delivery within 24 h.

Augmentation of labor with oxytocin was started in women who had cervical dilatation of 4 cm or more with unsatisfactory progress of labor (arrest of cervical dilatation of ≥2 h and/or inadequate uterine activity) after 6 h of the last prostaglandin dose in induction regimen.

Statistical analysis

The recorded data were analyzed using the Statistical Package for the Social Sciences, version 20.0 (SPSS Inc., Chicago, Illinois, USA). Data were expressed as mean and SD. Frequency was expressed in %. χ2 was used to find the association between two or more qualitative variables. Fisher's exact test was used for 2 × 2 tables when the expected cell count of more than 25% of cases was less than 5. Paired sample t test was used when comparing between related samples. P value is considered statistically significant if it is less than or equal to 0.05.


  Results Top


There were no statistically significant differences, as regards the mean age of the study population in both groups, the mean gestational age, BMI, and the mean preinduction Bishop score as the P value was 0.547, 0.438, 0.147, and 0.775, respectively [Table 1].
Table 1: Comparison between the studied women according to the type of amniotomy regarding demographic data

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There was statistically significant difference, as regards the duration of labor. Women in the early amniotomy group reported shorter labor duration of about 4 h than those of the late amniotomy group with P = 0.000. The mean duration from rupture of fetal membrane to delivery was 2.5 ± 0.85 in the late amniotomy group and 3.3 ± 1.05 in the early amniotomy group (P = 0.000) [Table 2].
Table 2: Comparison between the studied women according to the type of amniotomy regarding the clinical outcome of induction

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There were no statistically significant differences between both groups with regard to indication of induction, need for oxytocin, and cesarean section indication; the P value was 0.576, 0.416, and 0.345, respectively. The main indications for cesarean section in both groups were failure to progress and fetal distress [Table 3].
Table 3: Comparison between the studied women according to the type of amniotomy regarding the clinical outcome of induction

Click here to view



  Discussion Top


Cervical ripening is the conversion of the rigid cervical sphincter associated with maintenance of pregnancy to a complaint and readily dilatable structure[15].

According to the Bishop scoring system, no failures were encountered with a score of 9 or more. Failures reached a relatively low level of about 5% in the intermediary score subgroup 5–8. Lower scores (4 or less) had a significant higher failure rate, averaging 20% overall[16].

Continuous intravenous oxytocin infusion in doses not exceeding 3 ml/min is an effective method of cervical ripening. The problem is that it takes, an average, 72 h to obtain results, and the patients are reluctant to accept this extended procedure[17].

Intravaginal administration of 25 μg every 3–6 h is effective in women with an unfavorable cervix. The 25 μg dose is considered to decrease the need for oxytocin and achieve higher rates of vaginal delivery within 24 h of induction[18],[19].

Since the report on the use of misoprostol to induce labor at term, there have been an increasing number of published reports of its use in varying regimens[20],[21],[22].

The best method of cervical ripening remains controversial as no one method has been proven to be clearly superior[23].

The aim of our study was to compare between the effectiveness and safety of early versus delayed amniotomy after vaginal misoprostol for the induction of labor.

Both groups were similar at the baseline. There were no differences between groups in the demographic characteristics such as maternal age; the standard mean of age (years) in group A was (23.4 ± 2.9 years old) versus (24.3 ± 3.32 years old) in group B with P = 0.547; BMI (kg/m2) was 28.4 ± 2.4 kg/m2 in group A versus 28.2 ± 1.5 kg/m2 in group B with P = 0.147, and gestational age in group A was 41.02 ± 1.5 weeks versus group B 41.4 ± 1.4 weeks, P = 0.438. Also, there were no significant differences in indications for induction of labor and precervical ripening Bishop scores [group A (6.51 ± 0.75) vs. group B (6.46 ± 0.77), P = 0.775].

In our study, significantly shorter labor duration was recorded among patients assigned to the early amniotomy group in comparison with the late amniotomy group. The present findings were comparable to those of other randomized, controlled trials[24],[25],[26] that have also reported decreases in the duration of labor. Similar to the findings of the Cochrane review[27] of amniotomy, no increase in cesarean delivery rates was recorded among women who underwent amniotomy in the previous study.

Amniotomy and immediate oxytocin infusion are associated with the establishment of active labor at 4 h, a shorter amniotomy delivery interval, and greater maternal satisfaction[17].

Women who receive early oxytocin require less analgesia compared with those receiving oxytocin later[28]. Macones et al.[29] and Fraser et al.[30] found that routine early amniotomy is associated with a reduction in labor duration.

All these data agree with our results where more subjects in the early amniotomy group achieved vaginal delivery within 24 h than in the late amniotomy group[31 (77.3%) vs. 27 (67.50%), P = 0.19]. Women in the amniotomy group reported shorter labor duration of about 4 h than those of the control group (13.5 ± 2.2 vs. 17.4 ± 1.95 h, P = 0.000); mean duration from rupture of fetal membrane to delivery was 2.5 ± 0.85 in the late amniotomy group and 3.3 ± 1.05 in the early amniotomy group (P = 0.000). This difference was statistically significant.

The results of our study also match with the Macones et al.[29] study which showed that in prevention trials, early intervention with amniotomy and oxytocin appears to be associated with a modest reduction in the rate of cesarean section over standard care. Our study also matches with a recent study that found no difference between early amniotomy and standard therapy regarding the cesarean section rate during induction of labor.

Meta-analysis provides no support for the hypothesis that routine early amniotomy reduces the risk of cesarean delivery[28]. An association between early amniotomy and cesarean delivery for fetal distress is noted in one large trial[30]. This suggests that amniotomy should be reserved for women with abnormal labor progress[30]. The results of our study did not match with the above-mentioned studies, where the cesarean section rate was less in the amniotomy group [nine (22.5%) vs. 13 (32.5%)] in the late amniotomy group; this could be due to the fact that we used misoprostol 25 μg which was associated with less hyperstimulation syndrome and hypertonus uterus compared with oxytocin.

In this study, fetal distress in both groups was accounted for most of the indications for cesarean section. Group B had a higher rate than group A as it was six (66.6%) versus eight (61.5%) with no statistically significant difference (P = 0.345).


  Conclusion Top


In well-selected cases, vaginal misoprostol followed by early intervention with amniotomy for labor induction appears to be associated with higher successful vaginal delivery rate, shorter induction-delivery interval, and better neonatal outcome over standard care.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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29.
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