Comparative study of 25 μg oral and 25 μg vaginal misoprostol administration for induction of labour at term

Introduction: A successful induction of labour includes adequate uterine contraction after the addition of the inducing agent, and progressive dilatation of the cervix, thereby resulting in the successful vaginal delivery. Misoprostol has been found to be more superior than other conventional methods and resulting in shorter induction to delivery time. Materials and Methods: 100 patients with 36 or more gestation period, requiring induction, were divided into 2 groups of 50 each. Group I were given 25 μg misoprostol orally and Group II were given vaginally. Dosage was repeated every 4th hourly and monitored. Results: The major indications of labour were severe preeclampsia, post dated pregnancy, mild preeclampsia, and PROM. Majority of the women who had undergone induction of labour were primigravida. 90% of patients in the vaginal group delivered vaginally as compared to 80% of the patients in the oral group. Caesarian section was planned in the cases of fetal distress, failure to progress or failed induction of labour. Conclusion: Women who received vaginal misoprostol experiences shorter induction delivery times, required fewer doses of misoprostol amd required oxytocin augmentation less frequently than those who received oral misoprostol. © 2020 Published by Innovative Publication. This is an open access article under the CC BY-NC license (https://creativecommons.org/licenses/by-nc/4.0/)


Introduction
The ability to induce labour has been of interest to many societies from time memorial. For majority of the women, labour starts spontaneously and results in vaginal delivery at or near term. 1 However, due to many reasons, induction of labour becomes a necessity.
According to the National Centre for Health Sciences, in 2017, the number of women who had undergone induction for labour were 25.7%, while in 2012 it was 23%. The rates are continuing to increase due the increase in the prevalence of obesity among expectant women. [2][3][4][5] A successful induction of labour includes adequate uterine contraction after the addition of the inducing agent, and progressive dilatation of the cervix, thereby resulting in the successful vaginal delivery. There is no point in The condition of the cervix is highly important for the successful vaginal delivery to take place. A "ripe" soft yielding cervix requires a lower quantum of uterine work than an unripe hard and rigid one. An unripe cervix fails to dilate well in response to myometrial contractions. 6 Induction of labour involves ripening of the cervix with the help of a prostaglandin E2 analog such as dinoprostone, amniotomy and oxytocin given intravenously. However, now many studies have shown that misoprostol, which is a prostaglandin E1 analogue normally used for protection against gastric ulcers also causes uterine contractions. [7][8][9][10][11][12] Misoprostol has been found to be more superior than other conventional methods and resulting in shorter induction to delivery time https://doi.org/10.18231/j.ijogr.2020.071 2394-2746/© 2020 Innovative Publication, All rights reserved. 331

Materials and Methods
This study was done in the department of Obstetrics and Gynecology at Maheswara medical college from Jan-2016 to Nov 2016. A total of 100 patients with indications of induction in the third trimester were selected for the study. The nature of the study was thoroughly explained to the patients and their relatives and informed consent was taken from all of them. The inclusion criteria which was considered was 36 weeks or more of gestation, with single fetus and absence of uterine contractions, with vertex presentation and original bishop score of less than 6. Patients with cephalopelvic disproportion, abruptio placentae, Placenta praevia, malpresentation and previous uterine incision were all excluded from the study. Those who refused informed consent also were excluded from the study, and another patient was chosen randomly to make the total number as 100.
The indications for induction of labour in these patients was presence of mild to severe pre-eclampsia, antepartum eclampsia, post dated pregnancy, intra-uterine death, PROM, oligohydramnios and polyhydramnios.
They were divided into 2 groups of 50 each. Group I weregiven 25 µg misoprostol orally and Group II were given vaginally. The cervical status was assessed by Bishop score prior to the induction and prior to each dose. Dosage was repeated every 4 th hourly until an adequate contraction pattern set it (establishment of 3 uterine contractions in a period of 10 minutes) or until the cervical dilatation reaches 4 cms, with a maximum of 6 doses. After the induction, the patients are monitored for signs of labour and when this ensues, they are closely monitored for maternal vital signs, progress of labour and fetal heart rate which is monitored by intermittent auscultation.
The maximum amount of misoprosol that can be given to the patients is 150 µg, i.e 6 doses, in both oral and vaginal cases. In case, the labour contractions did not occur ever after 4 hours, it is considered to be a failed induction and other methods of inductions like oxytocin, cerviprime gel was done. If the membranes did not spontaneously rupture, they were ruptured when the cervix was completely effaced with a cervical dilatation of ≥ 4cm.
The number of doses of misoprostol given to the patients, the interval between the induction and the inset of the uterine contrations, induction -delivery interval, mode of delivery, maternal and neonatal complications and adverse effects of the drug like fever, diarrhea, nausea etc were carefully noted.
Tachysystole i.e more than 5 contractions per 10 minutes without any change in fetal heartbeat for 2 consecutive 10 minute period were noted. Hyperstimulation or the exaggerated uterine response if any and accompanied by fetal heart rate deceleration of tachycardia were also noted.

Results
The total number of patients in the study were 100, divided into Group I for oral misoprostol induction of delivery and 50 were in Group to where misoprostol was administered vaginally for the induction of labor.
Out of the indications of labour, the most common was severe pre-eclampsia with 11 cases (22%) in the oral induction while the same was only in 6 cases (12%) in the vaginal cases. 9 patients (18%) each had post dated pregnancy, mild pre-eclampsia, and premature rupture of membranes (PROM).8 (16%) of the patients were full term 3 (6%) had antepartum eclampsia.
Among the patients who underwent induction vaginally, the most common indication was post dated pregnancy, seen in 13 (26%) of the cases, followed by full term in 10 (20%) of the cases. 7 (14%) had antepartum eclampsoa ( Table 1).
More number of patients in the vaginal group i.e 45 (90%) of the cases delivered vaginally as compared 40 (80%) of the patients in the oral group. Caesarian section was planned in the cases of fetal distress, failure to progress or failed induction of labour. The cases of failed induction were delivered either vaginally using syntocinon or cerviprime of by LSCS (Table 3).

Discussion
One of the highest synthetic prostaglandin E1 analogue which is widely in use by the obstetricians in the induction   of labour is misoprostol. 13 It is very stable and its absorption is dependent on the application and the dosage of the drug. 14 In the present study, the majority of the patients who required induction of labour were those who were suffering from pre-eclampsia or those who were full term with no pains yet. Other causes were rupture of the membranes or post dated pregnancy. Importantly, the most common indication for the inductions in most of the other studies was post term pregnancy, hypertension during pregnancy, and pre rupture of membranes. [15][16][17] Most of the patients in our study were primigravida (56%), which included 60% in Group I and 52% in Group II. This difference was not significant as the patients were distributed in both the groups randomly. A study by Young et al found no significance in the parity in the two groups and for the time and the outcome of delivery. 18 Among the patients who received the induction orally, 24% of them required 2 doses followed by 22% who needed 4 doses. Among the patients with vaginal induction, 40% needed only 2 doses.
Most of the patients 80% in oral induction and 90% in the vaginal induction had vaginal delivery. Caesarean delivery was comparatively more among the patients who underwent oral induction (16%) rather than those who had vaginal induction (6%). This was corelated by a study by Handal-Orefice where the frequency of caesarean was observed among the persons with oral induction rather than vaginal induction of labour. 19 A study by Komala et al found no significance difference in the time for vaginal delivery but showed a lower caesarean delivery rate among the patietns with oral induction. 20 Similar was the cases in studies by Ezechukwu et al and Wing et al. 21,22 In a double blind study by Handal-Orefice, 25 micrograms of misoprostal for vaginal induction and 50 micrograms for oral induction was used with similar results. They had shorter labour induction time with low caesarean rates. 19 Another study by Morris et al also reported similar outcome with more than 90% of the patients delivering safely by vaginal delivery. This shows that misoprostol in both vaginal induction as well as oral induction is safe for use.

Conclusion
Women who received vaginal misoprostol experiences shorter induction delivery times, required fewer doses of misoprostol amd required oxytocin augmentation less frequently than those who received oral misoprostol. The increased efficacy associated with the vaginal misoprostol raises the possibility of a local cervical effect with vaginal administration.
Despite this, in comparison to the oral misoprotol, high rates of tachysystole and hyperstimulation associated with vaginal misoprostol is a cause for concern, prompting the patients to prefer the oral route of induction of labor.

Source of Funding
None.

Conflict of Interest
None.