Prostaglandin E2 gel In ripening of cervix in induction of labour.HS Warke, RM Saraogi, SM Sanjwalla
Dr. R. N. Cooper Hospital, Vile Parle, Mumbai, India., India
A study was done in 75 patients who underwent induction of labour with Prostaglandin E2 gel. All these patients had an unripe cervix. The commonest indications were post-datism, intrauterine growth retardation and pregnancy-induced hypertension. All patients were primigravidas with singleton pregnancy and beyond 35 weeks of pregnancy. The mean Bishop score at the time of instillation was less than three. The improvement of another 2-3 points within six hours and by 7-8 points within 12 hours was found after instillation of the gel. 92% of the patients went into spontaneous labour and 8% required reinstillation. The incidence of failed induction was 1.33%. The mean duration of latent phase was 10.34 hours. Induction delivery time was 16.43 hours. 68.1% patients required augmentation of labour and 31.9% did not require augmentation of labour with oxytocin drip. The incidence of vaginal delivery was 81.33% and that of caesarean section was 17.33%. The commonest indication of caesarean section was foetal distress.
Keywords: Cervical Ripening, Dinoprostone, Female, Human, Oxytocics, Pregnancy,
Modern obstetrics aims at improving the safety of the mother and the foetus during antenatal period as well as parturition. The aim of induction of labour is to perform safe vaginal delivery before term.
Spontaneous labour and vaginal delivery is preceded by a cascade of synchronised events, which leads to ripening of cervix. Calder said that ripening of cervix governs the ease and success of induction of labour. Prins et al has rightly said that if ripening of cervix fails to occur, then delivery and labour may be prolonged and many a times unsuccessful. Induction of labour in a patient with an unripe cervix is always a formidable challenge to the clinician.
Oral and parenteral routes of administration of prostaglandins are associated with unacceptably higher rates of gastrointestinal side effects (25-55%). Local applications of Prostaglandin E2 (PGE2) gel in the form of intracervical gel are associated with fewer side effects. A number of reports have appeared in literature favouring the intracervical route, claiming not only advantage of shorter induction delivery time and fewer side effects but principally focusing on one time dose response which makes its administration simple and causes minimal discomfort to the patients.
A study was done at our institute in 75 patients to assess the efficacy and safety of intracervical PGE2 gel in induction of labour. In this study the PGE2 gel commercially available Cerviprime (Astra IDL, Banglore, India) containing 0.5 mg of PGE2 or dinoprostone was used for ripening of cervix. Labour was induced and whenever required augmented by oxytocin infusion in the form of a drip.
For the purpose of standardisation, patients with singleton live foetus in cephalic presentation with gestational age of 35 completed weeks or above and Bishop score of less than 3 were selected. In patients where the date of the last menstrual period was not known dating of pregnancy was estimated by an early ultrasound. Patients with any previous uterine surgery, vaginal bleeding, ruptured membranes, cephalopelvic disproportion hypersensitivity to prostaglandins, allergy or asthma were excluded. The patients who fulfilled the inclusion criteria were admitted and evaluated for maternal and fetal wellbeing. Obstetric ultrasound and non-stress test were carried out. The patients with reactive non-stress test were taken for the study. Written informed consent was taken and Bishop score determined. The method followed is outlined in [Figure - 1]. Cerviprime gel was introduced intracervically with strict aseptic precautions.
The first per vaginum examination was carried out after six hours and Bishop score recorded. The cervix was graded as a favourable cervix when the Bishop score was equal to or greater than six points. The patients who had a favourable cervix within 24 hours were grouped together as Group I. These patients either went into spontaneous labour or the labour was augmented with oxytocin infusion. The patients who did not have a favourable cervix at the end of 24 hours required reinstillation and were grouped as Group II. If ripening did not occur in-spite of two instillation then the induction was termed as failed induction.
Clinical monitoring of patients
The patients' vital parameters were monitored and per abdomen examination was done half hourly giving special attention to fetal heart sounds and uterine activity. The cervical dilatation and Bishop score was assessed at intervals. Progress of labour was charted by a partogram.
The common indications for induction of labour with intracervical PGE2 gel were postadatism (52%). Pregnancy - induced hypertension (33.33%) and intrauterine growth retardation (14.67%). The mean gestational age was 38.9 weeks.
The mean Bishop score in this study was 2.24. There were only 12 patients with extremely poor bishop score. This was because of the selection of patients who had gestational age of 35 weeks and above 33 (44%) patients had Bishop score of 2 and 30 (40%) patients had Bishop score of 3.
92% of the patients went into spontaneous labour (Group I) and 8% required reinstillation (Group II) [Table - 1]. The mean Bishop score at intervals of 6 hours and 12 hours was compared in both the groups [Table - 2]. On comparing the 0 hour status of both the groups a negligible change was found. But when the patients who required reinstillation were studied it was found that all the patients had a very poor Bishop score of 1 at the time of first instillation. Thus the first instillation caused an increase of 2 points.
The duration of latent phase was 10.2 hours and 12 hours respectively in Group I and Group II respectively, the mean being 10.34 hours. Induction delivery time was 16.25 hours and 18.5 hours in Group I and Group II respectively, the mean being 16.43 hours [Table - 3]. In Group I including 69 patients, 47 (68.19%) patients required augmentation and only 22 (31.9%) patients did not require augmentation. In group II (reinstillation group) including 6 patients all the patients who went in labour required augmentation.
The incidence of vaginal delivery was 81.33% and, caesarean section was 17.33% the commonest indication being fetal distress. The incidence of failed induction was 1.33% [Table - 4]. The incidence of lower segment caesarean section (LSCS) in reinstillation Group was extremely high. The indications for which LSCS was performed were foetal distress, abnormal labour patterns, arrest or protracted descent and hyperactivity. One patient developed hyperactivity within 1 hour of instillation of PGE2 gel and signs of foetal distress. This patient did not respond to Inj. Terbutaline (0.25 mg) given subcutaneously and thus LSCS was performed.
The mean birth weight was 2.24 kg. The low birth weight was due to the indication for which induction was performed. There was no neonatal death. Mean Apgar score at 1 minute was 8 and at 5 minutes was 9.
The commonest complications occurring after PGE2 gel instillation were vomiting in 10.67% cases, diarrhoea in 10.67% cases and hyperactivity in 2.67% cases. Traumatic postpartum haemorrhage occurred in only 1.33% cases and atonic postpartum haemorrhage in 2.67% cases. There was no life threatening complications.
At term a series of complex biochemical, physiological and physical processes cascade, resulting in delivery. Several events are modulated by neuroendocrine pathways, humoral transmission, steroids and local hormones. During the transition to the onset of labour the cervix becomes soft, short and cervical resistance decreases. This process is called as "cervical ripening". The success of induction depends on the degree of pre-labour changes.
Calder (1980) showed that prostaglandins ripen the cervix in essentially two ways.
1. Induce collagen breakdown
2. Alter tissue hydration and collagen binding by altering the glycosaminoglycan / proteoglycan composition.
In the non-pregnant state, the cervix consists of around 80% waterand it increases to around 86% in late pregnancy. Glycosaminoglycans are highly hydrophilic and increase tissue hydration. They thus destabilise the collagen fibrils and. promote ripening. The most abundant glycosaminoglycans in the cervix are chondratin sulphate and its epimer dermatin sulphate,.
Endocervical application of prostaglandin E2 gel has become increasingly popular following studies in Sweden. After these studies the use of PGE2 in the dose of 0. 5 mg has become standard.
In this study the improvement of Bishop score after 6 hours was 2 and after 12 hours was 7. Various studies have shown the beneficial effects of intracervical PGE2 gel in improving Bishop score, the improvement ranging from 3 to 7 points,. The success of induction of labour was found to be directly proportional to the Bishop score at instillation.
The mean duration of latent phase in this study was 10.2 hours. The 0 hour Bishops score will definitely have its effect on the duration of the latent phase.
The overall mean induction delivery time was 16.43 hours. Various studies have shown considerable variation as far as induction delivery time is concerned ranging from 9 hours (Noah et al) to 17.9 hours (Thiery et al). The parity of the patients considered also influenced the duration of labour. PGE2 gel has shown to shorten the induction delivery interval in many studies and thus will result in less fetal and maternal morbidity and mortality.
The incidence of caesarean section in our study was found to be 16.67% and incidence of failed induction was 1.33 %. The caesarean section rate quoted in international literature ranged from 6% to 26.66%.
The present study thus shows that a single application of intracervical PGE2 gel caused favourable changes in the cervix by increasing the Bishop score and shortened the induction de-livery interval with minimal side effects. To conclude intracervical PGE2 gel application is safe and acceptable method for induction of labour in patients with unfavourable cervix.
With the better methods for induction of labour and better techniques of evaluation of foetal well being the rate of induction of labour has further increased. An ongoing search for the better and safer methods for induction will continue in future.
The authors thank Medical Superintendent, Dr. Wadiwalla for granting us permission to publish hospital data.
[Figure - 1][Table - 1], [Table - 2], [Table - 3], [Table - 4]