Labour Induction with Intracervical Prostaglandin E2 Gel and Intravenous Oxytocin in Women with a Very Unfavourable Cervix

Summary: Two hundred and sixty-three gravid women having a very unfavourable cervix and requiring labour induction were studied; 80 primigravidas and 56 multigravidas were administered a single dose of intracervical prostaglandin E₂ gel (PGE₂) and 72 primigravidas and 55 multigravidas had labour induced with an escalating oxytocin infusion. After 24 hours 73.8% of the primigravidas induced with PGE₂ had delivered vaginally compared with only 52.8% of those induced with oxytocin. The incidence of Caesarean sections was very high (47.2%) in the primigravidas receiving an oxytocin infusion. In the multigravidas, there was no significant difference in the proportion of women who had delivered vaginally within 24 hours and in the percentage of Caesarean sections in the 2 induction groups. After 12 hours, a significant increase in the cervical score was seen in all women receiving PGE₂ intracervically. The fetal outcome and perinatal mortality were not affected by the mode of induction. Intracervical PGE₂ appears to be more effective than oxytocin in inducing labour in primigravidas having an unfavourable cervix, whereas in multigravidas, both methods appears to be equally effective.     

Oral Prostaglandin E2in Induction of Labour

Summary: In a randomised study of 207 patients, labour was induced with oral prostaglandin E₂in 107 and intravenous oxytocin (Syntocinon) in the remainder, half in each group with medication alone, the other half with fore-water amniotomy as well. Prostaglandin and oxytocin were found to be more effective when preceded by amniotomy. Once labour was established, the time taken to achieve vaginal delivery was the same with either drug, as also the number of successful vaginal deliveries. There were 6 failed inductions, but no statistical significance in the percentage differences between PGE₂ and oxytocin could be found. The two perinatal deaths which occurred could not be attributed to either drug. Oral PGE₂is therefore as effective as intravenous oxytocin with no observed hypertonus and little side-effects.     

Cervical Ripening Before Induction of Labour in Patients with an Unfavourable Cervix: A Comparative Randomized Study of the Atad Ripener Device, Prostaglandin E2 Vaginal Pessary, and Prostaglandin E2 Intracervical Gel

Summary: One hundred and nineteen women with singleton pregnancy and cephalic presentation requiring induction of labour in the presence of an unfavourable cervix (Bishop score ≤ 4) were studied. Five patients were excluded because of failure to comply with the protocol. Cervical ripening was carried out using 3 different methods; 36 used the Atad Ripener Device, 39 received 0.5 mg PGE, intracervical gel and 39 received at least one 3 mg PGE₂ intravaginal pessary. There were no differences in the demographic characteristics and the indications for induction. Five patients developed complications during the ripening period necessitating intervention; 3 required emergency Caesarean section and 2 delivered vaginally. Although statistically there were no differences among the 3 methods of cervical ripening, the power of the study is probably not large enough to show the differences. The PGE₂ pessary appears to be more effective with 68% of patients either going into labour during cervical ripening or succeeding in the cervical ripening compared to around 50% in the Atad and PGE, gel groups. The vaginal delivery rate was 87.2% in the pessary group compared to 72.2% in the Atad group and 84.6% in the gel group. The duration of labour was also shorter in the pessary group with 73.5% delivered within 24 hours compared to 57.7% in the Atad group and 57.6% in the gel group. Although the results of the Atad device seem to be inferior, the risk of uterine hyperstimulation from the use of the device is probably lower than that of the PGE₂ and may therefore be preferable in women with fetuses at high risk of fetal hypoxia.     

Uterine Rupture After Induction of Labour for Intrauterine Death Using the Prostaglandin E2 Analogue Sulprostone

A 30-year old pregnant woman who had had an earlier stillbirth and 2 children, the oldest of whom was delivered by Cesarean section, presented at the National University Hospital in Singapore at 32 weeks because she had not felt fetal movements for 3 days. Doptone did not detect a fetal heart beat and ultrasound confirmed intrauterine death. She did not have any soreness at the previous lower segment Cesarean scar. After she opted to have labor induced, health workers injected 0.5 mg of the prostaglandin E2 analogue, sulprostone, into a muscle every 6 hours. Painful uterine contractions did not start until after the 2nd injection of sulprostone. 20 hours after the 1st injection, her pulse increased to 100/minute, blood pressure fell from 120/70 to 80/50, and she began to perspire. She noted tenderness at the lower segment scar. Abdominal examination did not reveal any free fluid. There was no blood in the urine. 20 minutes after her blood pressure increased to 100/70, the woman had steady abdominal pain and vaginal bleeding. Her abdomen swelled and rebound tenderness occurred. Physicians diagnosed uterine rupture and performed a laparotomy promptly. They found 800 ml of free blood in the peritoneal cavity and a complete rupture all along the Cesarean scar. The removed the dead fetus and repaired the scar. They also applied Filshie clips on her Fallopian tubes since she wanted to be sterilized. She was discharged 7 days after laparotomy and recovered uneventfully. This case report confirms that vaginal delivery at term after lower segment Cesarean section is no guarantee against scar rupture in subsequent pregnancies, particularly when health workers use prostaglandins. Nevertheless, prostaglandins are still a reasonably safe and predictable method of terminating pregnancy even in cases of previous Cesarean section. It is important that health workers supervise closely women who have had a Cesarean section and are being administered a prostaglandin to terminate a pregnancy because of the possibility of uterine rupture.     

Oral Prostaglandins E2 and F2a in the Induction of Labour

Summary: Oral prostaglandins E₂ and F_2a were used to augment amniotomy in the induction of labour in 173 patients. The success rate was significantly higher with prostaglandin E₂ than with prostaglandin F_2a (89% and 75%, respectively). This was achieved despite a significantly lower incidence of gastrointestinal side effects. No serious maternal or fetal complications occurred with either drug. It is concluded that oral prostaglandin E₂ is more efficient than oral prostaglandin F_2a in the induction of labour.     

Prostaglandin E2, Fetal Maturation and Ovine Parturition

Summary: The major source of PGE₂ in ovine pregnancy is the placenta, with secretion occurring bidirectionally into fetal and maternal circulations. The placental output of PGE₂ appears to increase when demand on placental function is increased, suggesting that the normally observed increase in its concentration towards term is driven by the growing demands of the fetus. The fetal pituitary is also involved in the control of PGE₂ synthesis. PGE₂ has potent stimulatory actions on the fetal pituitary to increase both the absolute concentration and the bioactive fraction of ACTH-containing peptides in the fetal circulation. It also directly stimulates glucocorticoid secretion from the fetal adrenal gland.
We propose that PGE₂ provides a tonic stimulation of the fetal HPA axis in late gestation, contributing to phenomena such as the apparent insensitivity of the pituitary to Cortisol feedback and the increasing sensitivity of the fetal adrenal. Because of its apparent responsiveness to placental workload, it may transduce stimuli from the placenta and transmit them to the fetal HPA axis, giving a possible biochemical basis to the empirically observed correlation between fetal metabolic demand and gestation length.     

Induction of Labour by Amniotomy and Micro-infusion of Oxytocin (Syntocinon)

A method of induction of labour by amniotomy and micro-infusion of oxytocin (Syntocinon) is described. The micro-in- fusion reduces the amount of intravenous fluid required to effect delivery to less than 500 ml. in most cases.
There were no maternal complications and 96% of patients were delivered on the day of the infusion.
The Caesarean section rate was 3%. There was no perinatal mortality attributed to the method of induction.
The potential risks of the method are emphasized.     

Induction of Labour in Nulliparas with Poor Cervical Score: Oxytocin or Prostaglandin Vaginal Pessaries?

In a previous study nulliparas with poor cervical score (less than 5 out of 10) had a 43.5% Caesarean section (CS) rate of which 55% were for failed induction when labour was induced by artificial rupture of membranes and oxytocin infusion. In this study induction of labour by 2 doses of 3 mg prostaglandin E2 (PGE2) vaginal pessaries, 4 hours apart, and if necessary by artificial rupture of membranes and oxytocin infusion 24 hours later, resulted in a CS rate of 23.7% of which 38.9% were for failed induction. The latter regimen resulted in a significantly lower CS rate compared with labour induced by oxytocin infusion and rupture of membranes without the use of prostaglandins (p less than 0.001). In the prostaglandin group 53.3% were established in labour within 24 hours of inserting the pessary and in these patients the CS rate was 18.5%. In those who did not start labour and needed rupture of membranes and oxytocin infusion 24 hours after the first pessary, 34 (47.9%) had a good cervical score (greater than or equal to 6 out of 10) and 37 (52.1%) had a poor cervical score (less than or equal to 5 out of 10) at the time of amniotomy. The CS rates in these groups were 8.8% and 48.6% respectively (p less than 0.001). In nulliparas with poor cervical score induction is better performed with vaginal prostaglandin pessaries in order to reduce the high CS rate associated with artificial rupture of membranes and oxytocin infusion.     

The Safety of Vaginal Prostaglandin F2α for the Stimulation of Labour

Summary: In an audit of 15,102 consecutive deliveries between 1986 and 1991, 3,168 labours were induced with intravenous oxytocin and 824 with 40 mg prostaglandin F₂a (PGF₂α) vaginal gel. Four hundred and twenty women received PGF₂α alone and 404 received PGF₂α followed by oxytocin. The main aim of the study was to audit the safety of PGF₂01 gel to stimulate labour. There were no maternal or neonatal complications attributable to this therapy. In particular, there were no cases of uterine rupture or hyperstimulation requiring surgical or pharmacological intervention. There was little difference in the evidence for fetal distress between induction methods. Although the prostaglandin and oxytocin groups were not comparable in all respects, the results of this large retrospective study confirmed the results of smaller prospective randomized trials showing a significantly shorter labour and reduced analgesia, surgical delivery and postpartum haemorrhage rates in women treated with PGF₂α alone. This is the largest reported series of PGF₂α induced labours and provides evidence of its safety and is in keeping with physiological data suggesting that PGF₂α is the main prostaglandin and oxytocic associated with normal progressive labour. Its apparent safety and potential to reduce both intervention in labour and postpartum complications merits greater attention.     

Use of Vaginal Prostaglandin Gel before Induction of Labour

Summary: Tylose gel containing either 1.5 mg, 3.0 mg or 10.0 mg of prostaglandin Fact was inserted into the posterior vaginal fornix of 165 patients on the evening before induction of labour. A control group of 100 patients received the gel alone. There was a significant reduction in the induction-delivery interval in nulliparae receiving at least 3.0 mg of prostaglandin, whereas, in multiparae all doses achieved this effect. There was also a significant reduction in the incidence of forceps delivery in nulliparae who received 3.0 mg or more of the prostaglandin gel; however, there was no difference in the incidence of spontaneous labour, epidural anaesthesia or Caesarean section between the patients who received prostaglandin or those receiving gel alone.     

A Double Blind Dose Trial of Intravaginal Prostaglandin F2α for Cervical Ripening and the Induction of Labour

Summary: A randomised double-blind trial involving 90 patients was set up to compare the efficacy of 25 mg PG F_2α, 50 mg PG F_2α and a placebo on cervical ripening when given in a vaginal tylose gel on the evening before surgical induction of labour. Preliminary stretching of the cervix and sweeping of the fetal membranes was not undertaken. In the 30 control patients, labour was not initiated and the mean improvement in the cervical score before surgical induction the next morning was 0.86. In the group of 30 patients receiving 25 mg PG F_2α, labour commenced during the night in 9 patients and the mean improvement in the cervical score was 3.76 (P < 0.0005); the corresponding figures for the 30 patients receiving 50 mg of PG F_2α were 10 patients coming into labour and cervical score improvement of 4.63 (P < 0.0005). he difference in the mean improvement of the cervical score between the 2 prostaglandin groups was not significant. Significantly fewer prostaglandin-treated patients needed augmentation during labour with intravenous oxytocin (P < 0.025) and there was a significant increase in the spontaneous delivery rate in the combined prostaglandin-treated group (P < 0.025). There was no statistical difference in the outcome of labour between the 2 prostaglandin groups. It was not possible to predict the patients whose cervices would not respond to PG F_2α pretreatment (15%) or those in whom labour would be initiated (30%). No side effects were experienced.