Labour, Induced Clinical Trial
Official title:
Membrane Sweeping Versus Transcervical Foley Catheter for Induction of Labour in Women With Previous Caesarean Delivery
Nowadays, more and more women embark on pregnancy with previous Caesarean scar. One in five
pregnancies requires induction of labour. The use of non-pharmacological methods (methods
without using medication) has been gaining popularity for women who are not good candidates,
such as women with previous Caesarean scar, for an induction with medications such as
prostaglandin. Labour induction with prostaglandin carries higher risk of uterine rupture and
thus it is not routinely offered to women with previous Caesarean delivery in Sibu Hospital.
Non-pharmacological methods of induction of labour appear to be safe in women with previous
Caesarean delivery. However, various methods are available and the efficacy among them remain
in doubt.
In Sibu Hospital, membrane sweeping, which is a type of non-pharmacological method, is
routinely offered to women with previous Caesarean delivery who require induction of labour.
However, membrane sweeping may not exert its labour induction effect immediately and the
delivery may be delayed by up to 8 days. This may render a proportion of women to resort to
repeated Caesarean section for failed induction.
Transcervical Foley catheter insertion is another non-pharmacological methods for labour
induction. Foley catheter, which is made from latex rubber, is inserted into the womb. The
balloon will be inflated and this put pressure on the cervix and encourages dilatation. This
method may successfully stimulates labour and the catheter falls out once the cervix dilates
to 3 centimeters.
The benefits of the Foley catheter:
- A favourable and safe option for mothers who are hoping for a vaginal birth after
Caesarean. It is estimated that 4-7 in 10 women with previous Caesarean undergoing
labour induction with Foley catheter will have successful vaginal births.
- Cause the cervix to mechanically open without involving medication.
- Reduced risk of uterine rupture compared to induction with prostaglandin.
- Less risk of fetal distress compared to induction with prostaglandin.
The risks of Foley catheter:
- Vaginal bleeding (1.8%)
- Pain requiring removal of catheter (1.7%)
- Baby moving from head down to breech (1.3%)
- Fever (1%) which is lower than induction with prostaglandin.
- The risk of uterine rupture is similar to women undergoing spontaneous vaginal birth
after Caesarean.
The aim of this study is to compare the effectiveness of two types of non-pharmacological
methods, ie. membrane sweeping and transcervical Foley catheter for induction of labour in
women with previous Caesarean delivery.
Induction of labour (IOL) is an obstetric intervention to artificially initiate labour before
its spontaneous onset. It is undertaken when maternal or fetal risks of continuing pregnancy
outweigh the risks of IOL. The methods of IOL include pharmacological method (prostaglandin),
mechanical methods (transcervical Foley catheter and laminaria tents) and surgical method
(amniotomy). Pharmacological method and mechanical methods are preferred choice for IOL in
women with unfavourable cervix. Whereas surgical method is reserved for women with favourable
cervix in which membranes are accessible.
With the global rise in Caesarean section, more and more women embark on pregnancy with
previous Caesarean scar. It is estimated that one in every four term pregnancies requires
IOL. With IOL in previous Caesarean section, the risk of uterine scar rupture with subsequent
catastrophic maternal and neonatal outcomes is the greatest concern. Previous influential
study highlighted that IOL with prostaglandin conferred the greatest risk of uterine rupture
(2.45%) in women with one previous Caesarean delivery. On the other hand, the risks of
uterine rupture were lower and comparable among women whose labour induced without the use
prostaglandin (0.77%) and women with spontaneous labour (0.52%). Among the various IOL
methods, prostaglandin is more likely associated with shorter interval to achieve vaginal
delivery and avoidance of oxytocin augmentation. Nevertheless, mechanical methods have lower
risk of uterine hyperstimulation but have more risk of infection. As a result, obstetricians
are facing dilemma on deciding the safe and effective method of IOL in women with previous
Caesarean delivery.
In Sibu Hospital, membrane sweeping is routinely offered to women with previous Caesarean
delivery who require IOL. This technique involves the examining finger passing through the
cervix to rotate against the wall of the uterus, to separate the chorionic membrane from the
decidua, or to massage around the cervix if the os is closed. However, membrane sweeping may
not exert its cervical ripening effect immediately and the delivery may be delayed by up to 8
days. This may render a proportion of women to resort to repeated Caesarean section for
failed induction. The vaginal birth rates following membrane sweeping in women with unscarred
uterus are ranging between 78%-90%. Among women with previous Caesarean delivery undergoing
IOL with membrane sweeping, the reported vaginal birth rates were conflicting. A randomised
controlled trial by Hamdan et al. showed vaginal birth rate of 56.1%. Another comparative
study by Ramya et al. reported much lower vaginal birth rate of 17.3% which could be
explained by high rate of Caesarean Section for maternal request in this study. The average
intervals from sweeping to labour onset and to delivery were about 2 days and 4 days,
respectively. Membrane sweeping did not increase the risk of maternal or neonatal infection,
Caesarean section, postpartum haemorrhage and neonatal poor APGAR score, though discomfort
during vaginal examination, minor vaginal bleeding and irregular contraction were frequently
reported by women undergoing membrane sweeping. No cases of uterine rupture was reported
among women with scarred uterus undergoing membrane sweeping.
Pharmacological IOL method involving prostaglandin is avoided in Sibu Hospital in view of
higher risk of scar rupture and presence of limited number of consultants to cope with this
debilitating event. Non-pharmacological methods of IOL such as Foley catheter, double-balloon
catheter, hygroscopic cervical dilator (laminaria tent) etc are known to have lesser risk of
scar rupture. Double-balloon catheters are limited in numbers in this hospital and they are
costly. Laminaria tent is not available in this hospital. Foley cathter is a consumable item
in this hospital and thus is readily available all the time. Compared to double-balloon
catheter, Foley catheter has equivalent cervical ripening efficacy and safety profile. In
addition, Foley catheter is also cheaper and has shorter induction to delivery interval. All
these advantages make Foley catheter an ideal method of IOL for women with previous Caesarean
delivery.
Among women with previous Caesarean delivery underlying IOL with transcervical Foley
catheter, the reported vaginal birth rates are ranging between 43.5%-71.4%. The retrospective
cohort analysis by Bujold et al. compared the risk of uterine rupture among women with
previous Caesarean delivery undergoing spontaneous labour, induction by amniotomy with or
without oxytocin, or preinduction cervical ripening with transcervical Foley catheter. The
rates of uterine rupture were similar among the groups ((1.1% vs 1.2% vs 1.6%, p = 0.81).
However, transcervical Foley catheter appeared to be safer than low dose oxytocin infusion
for cervical ripening before amniotomy as the latter tended to be associated with risk of
uterine scar dehiscence. Another retrospective cohort study done by Gonsalves et al. showed
no case of uterine rupture among 68 women with previous Caesarean section undergoing IOL with
transcervical Foley catheter insertion.
The transcervical insertion of balloon catheter as a 'foreign material' may theoretically
increase the risk of uterine infection. But, the current data available are conflicting.
Meta-analysis by Heinemann et al. demonstrated that the Foley catheter was associated with a
significantly higher rate of maternal infections, defined as fever, endometritis or
chorioamnionitis, compared to the use of prostaglandins or oxytocin for induction of labour
(7.6% vs 5%, pooled OR 1.5, 95%CI 1.07-2.09). On the other hand, Cochrane Review concluded
that there is no evidence of an increased risk of infectious morbidity with balloon
catheters. In the PROBAAT-trial, comparing the Foley catheter with the use of vaginal
prostaglandin E2 gel, the rate of intrapartum infection was significantly lower in women with
the Foley catheter (1% vs 3%, p = 0.035). Two other trials evaluating labour induction with
balloon catheters after rupture of the membranes did not show an increased risk for maternal
infection.
Maslovitz et al. reported the rate of vaginal bleeding of 1.8% following transcervical Foley
catheter insertion. However, the bleeding was minor with unaltered haemoglobin levels and
coagulation profile. There was also no case of cervical tear which might result in postpartum
haemorrhage. Besides, risk of change of fetal vertex presentation to breech was reported to
be 1.3%. This was probably related to concomitant presence of unengaged free-floating fetus
and contraction following Foley catheter insertion which resulted in flipping movement of the
fetus. Risk of poor APGAR and NICU admission was not significantly higher compared to other
IOL methods eg. prostaglandin and oxytocin.
Till date, there is paucity of evidence on the superiority of membrane sweeping and
transcervical Foley catheter in IOL in previous Caesarean delivery. Both methods have the
same mechanism action by increasing local production of endogenous prostaglandin. The aim of
this study is to evaluate the effectiveness of membrane sweeping and transcervical Foley
catheter insertion for IOL in women with previous Caesarean delivery.
The investigators had searched electronic databases including PubMed, Cochrane Library,
Scopus, Ovid, JSTOR and Google Scholar. The investigators found that there was no study
comparing these two IOL methods, thus no prior information is available for sample size
calculation. Based on Julious SA, the investigators recruited 24 subjects (a sample size of
12 per group) from 15 February 2018 to 8 May 2018 and performed an interim analysis to
calculate the actual sample size required for a full randomised controlled trial (RCT). The
justifications for this interim sample size were based on rationale about feasibility,
precision about the mean and variance, and regulatory considerations. The justifications for
this interim sample size are based on rationale about feasibility, precision about the mean
and variance, and regulatory considerations.
The final sample size was calculated based on the study primary outcome of achievement of
favourable cervix (Bishop score of 8 or more) within 48 hours of IOL. From the interim
analysis, the investigators found that the rate of favourable Bishop score achieved within 48
hours of IOL was 58.3% for membrane sweeping arm and 91.7% for transcervical Foley catheter
arm. The investigators used the following formula by Fleiss JL. 1981 to calculate the final
sample size. With α at 0.05 and power at 0.8, total of 52 subjects (26 subject in each arm)
need to be recruited. With the estimated dropout rate of 15%, the final sample size required
is 60 subjects, which means a further 36 subjects (18 subjects on each arm) will be recruited
to complete the study. In addition, data of the initial 24 subjects (12 per arm) recruited
will be included in the final data analysis. This further recruitment will not affect the
randomisation of the previous and future subjects because blocked randomisation, in a block
size of 6 and an allocation ratio of 1:1 is used. Furthermore, there is no change in the
methodology, scale and instrument of the research.
The investigators had applied ethical approval of the recruitment of a further 36 subjects
from the Malaysia Research and Ethics Committee, Ministry of Heath Malaysia and the
application was approved on 12 June 2018.
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