Oxytocin versus vaginal misoprostol for induction of labour in pregnant women with term pre-labour rupture of membranes

INTRODUCTION

Labor induction means stimulation of the uterine contractions for the production of deliveries before the start of spontaneous labour. The normal childbirth process is categorized into three stages of labor: the shortening and dilatation of the cervix, the descent and delivery of the fetus and placenta. ¹

In obstetric practise, there are numerous indications for induction of labour. The most common indication of which is the prolonged gestational age. It is well understood that induction can be difficult and often unsuccessful with an unripe cervix. In modern practise, It is allowed to use an agent to ripen the cervix prior to induction. 2 Oxytocin and prostaglandins are the most often utilised pharmacological drugs for labour induction. Because of ethical and social concerns concerning misoprostol usage as an abortifacient medicine, the most common form of labour induction is the use of oxytocin. ³ 

Misoprostol is more effective than oxytocin in minimising postpartum haemorrhage and inducing labour on time, according to several studies. In the

published series, however, misoprostol dosage, administration interval, and administration route were all different. . ⁴

Higher doses are linked to an increased risk of uterine hyperactivity, including foetal heart rate fluctuations and other problems.

Despite numerous reports on the subject, the efficacy and safety of oxytocin and misoprostol on mothers and foetuses remain unknown. ⁵

A review of the most recent misoprostol research for labour induction has been conducted. In most trials, misoprostol appears to be at least as effective as conventional techniques, the widely varying dosage regimens and small number of women studied do not allow for an adequate assessment of safety ⁶. Concerns have been raised about the widespread use of misoprostol in clinical practise, with arbitrary dosages and no registration or proper monitoring for adverse events, as well as reports of complications such as uterine rupture.

Misoprostol administered orally has been shown to be as safe and effective as misoprostol Women favour vaginal induction of labour since it is administered vaginally. 7

The goal of this study was to compare the efficacy and safety of vaginal misoprostol against intravenous oxytocin for induction of labour in pregnant women with term prelabour membrane rupture.

PATIENTS AND METHODS

This was a randomized controlled trial study conducted at patient at Obstetrics and Gynecology Department of Al-Hussein University Hospital from July 2021 to February 2022.

Sample size: Approximately two groups were randomized to the participating patients, the Misoprostol group "Group I" (n = 55) and the Oxytocin group "Group II" (N = 55). These randomizations were performed using a randomized computer selection and this randomized sel.

By assuming that mean ±SD of interval by hours from induction to vaginal delivery is 16.2 ± 5.1 in misoprostol and 13.2 ± 6 in oxytocin. The sample size is110 (55 in each group) using OPENPI at power 80% and C.I 95 % (127)

Ethical consideration and Study approval: Before beginning the study, The council of Obstetrics and Gynecology Department of Al-Hussein University Hospital, Al-azhar University declared the protocol and other associated documentation for Ethical and Research approval.

Inclusion criteria: Women aged (20-35) years with gestational age (37-41) weeks, singleton pregnancy, presentation of Cephalic, rupture of the membrane "gush of fluid" from amniotic sac and The most reliable approach for confirming ruptured membranes is direct sight of amniotic fluid in the posterior vaginal vault (pooling) (Duff, 2016). Two simple laboratory tests can be used when a physical examination is difficult.  (nitrazine paper test and positive fern test)

 Exclusion criteria: Contra indication of induction of labor e.g. uterine scar, multiple gestations, IUGR, active herpes infection, oxytocin or misoprostol allergy, pelvic dystocia, foetal weight greater than 4,000 g (Maanosomia) or foetal deformity, signs of cephalopelvic disproportion All included women were being subjected to:Full medical history for evaluating: All women included have been subjected to full medical history for evaluating  age, Parity & gravidity, gestational Age according to last menstrual period or U/S, medical and surgical history (DM, HTN, Hepatic, renal and allergy and cardiac) , previous uterine surgery (myomectomy or CS) and previous   mode of delivery (VD or CS).

Complete clinical examination: Full Obstetric examination, Abdominal examination: Inspection: Abdominal contour, surgical scars, hernia orifices, umbilical site for discharge or nodules. Palpation: Superficial palpation to detect any tenderness, rigidity, or mass. Auscultation: FHS: can be heard by sonicaid. Local examination: Inspection: for any vaginal bleeding or fluid. Bishop score In this study, the number of participants was kept to a minimum of six. The Bishop Score assigns points to five aspects of the pelvic exam: dilatation, effacement of the cervix, station of the foetus, cervix consistency, and cervix position.

U/S evaluation: Viability of the fetal, expected gestational age, presentation of the fetus, expected fetal body weight, link to the index of amniotic fluids, the Placental site and biophysical Profile including NST will be determined through the U/S evaluation.

Laboratory assessment    (Complete blood picture, Liver and renal function test, Coagulation profile, and Fetal evaluation (CTG)) were all performed.

Neonatal Assessment immediately after delivery   (APGAR score in the 1st minute, APGAR score in the 5th minute, Fetal birth weight, Head circumference and NICU admission)

Maternal assessment: (Success of VD or emergency CS, Duration (hours) to active phase, Time from induction of labor to delivery and maternal complications as cervical or vaginal tear or Blood transfusion; should be performed to all cases.

Method: Drug prescription method:

The Misoprostol tablet: Women received one tablet of 25 mcg of misoprostol vaginally. Misoprostol was given at a dose of 25mcg/2hour at first, until enough uterine contractions were achieved.

The Oxytocin solution: An IV drip infusion of 2mIU/min (4 drops per minute) was given to women using a syringe pump. Oxytocin in 500 cc of glucose at 5 percent was used to make this. Increases of 2mIU/min were made to the dose every 15 minutes for 3-5 minutes, or until the desired contraction rate of 3-5 every 10 minutes was obtained. Oxytocin is administered at a maximum dose of 36mIU/min until enough uterine contractions are achieved.

Follow up by

Vaginal examination is performed every 2 hours for the assessment of cervical dilation and effacement as well as the condition of intoxication on the partogram. CTG: when CTG results were unsatisfactory (varying excessive or late decelerations), we discontinued induction. Assessment of uterine contractions: A uterine contraction should occur every hour (3-5 every 10 minutes, lasting 40-60 seconds) with the discovery of any abnormalities. Adequate hydration and analgesia was done using crystalloids and narcotics respectively if indicated.

Outcomes: To compare the efficacy of the two medications, the following primary outcomes were used: The induction interval is the time between induction and the early signs of labour (From the time of the first misoprostol solution dose in group I to the time of group II: from the first oxytocin infusion to the commencement of regular uterine contractions) There is a period of time between induction and delivery (starting from the time of first dose of misoprostol solution in Group I and oxytocin infusion in group II till delivery by any route). Secondary outcomes included mode of delivery, uterine hyperactivity, maternal side symptoms (nausea, vomiting, diarrhoea, shivering, and headache), and newborn outcomes (Apgar score less than 7 at 5 minutes).  The success of induction and safe VD were the study's end points. Women in groups I and II who got the indicated treatment, misoprostol in group I and oxytocin in group II, had their primary and secondary outcomes compared.

Statistical analysis: The average plus or minus standard deviation was used to illustrate the data. The statistical software programme SPSS 16.0 was used to conduct the investigation (SPSS Inc, Chicago, IL, USA). To investigate temporal intervals, the Mann-Whitney U test was applied. Use the 2 for qualitative variables and the Student's t-test for quantitative variables. The significance threshold was set at a 0.05 p-value.

RESULTS

This study was conducted at Al-Hussein University Hospital covering the period from the first of July 2021 to the February 2022. A total number of 110 pregnant women at full term were admitted for induction of labor at this period.

The patients were randomly divided into two groups: Group I: Includes 55 patients those patients who had received vaginal misoprostol for induction of labor.  Group II: Includes 55patients those patients   who received oxytocin infusion for induction of labor

Table 1: Demographic characteristics of studied group

Table 1: In terms of mother age, gestational age, bishop score, and BMI, there was no statistically significant difference between the two groups.

Table 2: induction time

Table 2: Both the mean time from induction to active phase and the mean time from induction to delivery were considerably shorter in the misoprostol group than in the oxytocin group (10.6 and 13.4 hours against 12.9 and 15.8) hours, with p-values of 0.05, which are statistically significant.

Table 3: Mode of delivery

Table 3: in misoprostol group successful VD was at a higher rate than oxytocin group and C.S was lower than oxytocin group but this difference was not statically significant. , The chi-square statistic is 0.2657. The p-value is .606231. The result is not significant 

Table 4: uterine hyperactivity  

Table 4: it was found that out of 55 women with misoprostol group (7.27%) had uterine tachysystole and (1.81%) had hypersysytole versus (10.90%) had tachysystole and ( 1.81%) had hyper systole in oxytocin group. There was no statistically significant difference in uterine complications in misoprostol group and oxytocin group.

Table 5: maternal side effects

 Table 5: no significant difference found between the 2 groups in terms of maternal side effect. The common maternal side effect was shivering its incidence in both group (14.54%, 16.36%) also nausea (10.9%) in misoprostol group and oxytocin group (9.099%) respectively. Postpartum hemorrhage is found more than in oxytocin group but without significance difference

Table 6: Neonatal outcome

Table 6: When the infant outcomes in this trial were analysed, the misoprostol group was found to have a decreased incidence of Apgar scores at 5 minutes less than 7 at the end. between two group showing closure safety in neonates but without significance differences. NICU admission was found less in misoprostol group comparable to oxytocin group but without significance differences.