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Trial registered on ANZCTR

Registration number

ACTRN12618000510246

Ethics application status

Approved

Date submitted

2/04/2018

Date registered

9/04/2018

Date last updated

14/02/2020

Date data sharing statement initially provided

11/03/2019

Type of registration

Prospectively registered

Titles & IDs

Public title

Measuring the clinical effectiveness and healthcare experiences for women undergoing a balloon induction of labour, where the balloon is used for 6 hours compared to 12 hours.

Scientific title

Amongst women undergoing induction of labour using a balloon catheter, is leaving the balloon in for 6 hours, compared to 12 hours, associated with similar changes in the cervix to prepare for labour, similar clinical outcomes, and a similar healthcare experience?

Secondary ID [1]

Nil known

Universal Trial Number (UTN)

U1111-1211-6521

Trial acronym

SILVER Balloon

Linked study record

Health condition

Health condition(s) or problem(s) studied:

Induction of labour

Condition category

Condition code

Reproductive Health and Childbirth

Childbirth and postnatal care

Intervention/exposure

Study type

Interventional

Description of intervention(s) / exposure

Women randomised to the 6-hour arm will have a balloon catheter inserted by an experienced clinician (midwife, Registrar or obstetrician) and remain in hospital, Clinical staff will endeavour to review the women at 6-hours following insertion of the balloon catheter, deflate the balloon, attempt an amniotomy and commence an oxytocin infusion as soon as possible. The induction process for women in the trial will be very similar to usual clinical practice, except that the balloon catheter will be removed at 6 hours. Protocol compliance will be monitored by a research midwife.

Intervention code [1]

Treatment: Devices

Comparator / control treatment

Women randomised to the 12-hour arm will have a balloon catheter inserted by an experienced clinician (midwife, Registrar or obstetrician) aand remain in hospital Clinical staff will endeavour to review the women at 12-hours following insertion of the balloon catheter, deflate the balloon, attempt an amniotomy and commence an oxytocin infusion as soon as possible. The induction process for women in the trial will be very similar to usual clinical practice, Protocol compliance will be monitored by a research midwife.

Control group

Active

Outcomes

Primary outcome [1]

Change in cervical favourability (as measured by the modified Bishop's score)

Timepoint [1]

At time of removal of the balloon catheter

Secondary outcome [1]

Mode of birth, as recorded in the hospital records

Timepoint [1]

At the time of birth

Secondary outcome [2]

Time from insertion of balloon catheter until birth, as recorded in the hospital records

Timepoint [2]

At the time of birth

Secondary outcome [3]

Time from amniotomy until birth, as recorded in the hospital records

Timepoint [3]

At the time of birth

Secondary outcome [4]

Epidural use, as recorded in the hospital records

Timepoint [4]

At the time of birth

Secondary outcome [5]

Admission to a neonatal nursery, as recorded in the hospital records

Timepoint [5]

At the time of birth

Secondary outcome [6]

Health status of the baby at time of birth will be assessed using Apgar score at 5 minutes of age, as recorded in the hospital records

Timepoint [6]

At the time of birth

Secondary outcome [7]

Arterial cord blood pH < 7.1, tested using an arterial blood gas analyses

Timepoint [7]

At the time of birth

Secondary outcome [8]

Healthcare experience (as measured by the Experiences of Induction Tool)

Timepoint [8]

Between 48h and 7 days following birth

Secondary outcome [9]

Total healthcare costs. Information used to calculate this will be drawn from the hospital record, patient administration system, and operating room data systems,. Where possible, this will be calculated at the patient-level using a bottom-up methodology. Where this is not possible, cost will be ascribed using the apportioned cost per minute spent in the various clinical areas. Costs will be calculated from the perspective of the hospital and the time horizon will be from hospital admission until discharge of both mother and baby.

Timepoint [9]

Time of hospital discharge

Eligibility

Key inclusion criteria

All women with live singleton pregnancies greater than or equal to 37+0 weeks booked for induction of labour and requiring cervical priming (i.e. the cervix to be softer, shorter, dilated)

Minimum age

18 Years

Maximum age

No limit

Sex

Females

Can healthy volunteers participate?

Key exclusion criteria

Major congenital abnormality; multiple pregnancy; fetal death in utero; any contraindication to vaginal birth; previous caesarean section; modified Bishops score of 7 or more at commencement of induction of labour; women <18 years; inability to consent.

Study design

Purpose of the study

Treatment

Allocation to intervention

Randomised controlled trial

Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)

Randomisation will be according to computer-generated random allocation list into two study arms. Sealed opaque, sequentially numbered envelopes will be prepared. Randomisation will be performed approximately 8-24 hours prior to commencing the IOL.

Methods used to generate the sequence in which subjects will be randomised (sequence generation)

Simple randomisation using a randomisation table created by computer software (i.e. computerised sequence generation). Randomisation will be stratified by parity.

Masking / blinding

Open (masking not used)

Who is / are masked / blinded?

Intervention assignment

Parallel

Other design features

N/A

Phase

Not Applicable

Type of endpoint/s

Efficacy

Statistical methods / analysis

Statistical analyses of the data will be performed by the investigators with support from Mater Research. The initial analysis will assess the adequacy of randomization procedure to ensure comparability of the study groups. In this analysis demographic and other baseline characteristics will be compared. Primary and secondary outcomes will be assessed comparing the study groups. Analysis will be by intention-to-treat. Data from women who withdraw their consent will not be included in the analysis. Subgroup analyses will be undertaken, comparing outcomes for nulliparous versus multiparous women, and for women with more and less favourable cervices at time of commencement of IOL. The Chi squared test will be used for categorical outcomes and student’s t-test for continuous data. If imbalance is identified in important baseline characteristics or demographics, a second analysis will be undertaken controlling for these factors using multivariate analysis. The level of significance for the primary outcome measures is set at 0.05 and Bonferroni adjustment for multiple comparisons will be undertaken for secondary outcome measures.

Recruitment

Recruitment status

Not yet recruiting

Date of first participant enrolment

Anticipated

1/09/2020

Actual

Date of last participant enrolment

Anticipated

1/09/2022

Actual

Date of last data collection

Anticipated

Actual

Sample size

Target

858

Accrual to date

Final

Recruitment in Australia

Recruitment state(s)

QLD

Recruitment hospital [1]

Mater Mother's Hospital - South Brisbane

Recruitment postcode(s) [1]

4101 - South Brisbane

Funding & Sponsors

Funding source category [1]

Hospital

Name [1]

Mater Misericordiae Ltd

Address [1]

Raymond Terrace
South Brisbane, QLD, 4101

Country [1]

Australia

Primary sponsor type

Hospital

Name

Mater Misericordiae Ltd

Address

Raymond Terrace
South Brisbane, QLD, 4101

Country

Australia

Secondary sponsor category [1]

None

Name [1]

Address [1]

Country [1]

Ethics approval

Ethics application status

Approved

Ethics committee name [1]

Mater Group Human Research Ethics Committee

Ethics committee address [1]

Raymond Terrace
South Brisbane, QLD, 4101

Ethics committee country [1]

Australia

Date submitted for ethics approval [1]

03/04/2018

Approval date [1]

19/06/2018

Ethics approval number [1]

Summary

Brief summary

Induction of labour (IOL) is one of the most frequently performed obstetric interventions. In high-income countries nearly one-third of all pregnant women undergo IOL. The process of IOL commonly involves cervical ripening, using mechanical or pharmacological methods; however, the optimum protocol of IOL remains undetermined.  For almost 50 years, balloon catheters have been used to mechanically ripen the cervix. Balloon catheters apply direct pressure on the internal os of the cervix, stretching the lower uterine segment and indirectly increasing release of endogenous prostaglandins.  In recent years, there has been a shift in clinical practice favouring mechanical methods in response to growing evidence of both efficacy and safety. In randomised controlled trials and meta-analyses mechanical methods appear comparable to pharmacological methods for successful IOL without the complication of uterine hyper-stimulation.  Trends toward a reduction in instrumental births, fetal acidaemia and post-partum haemorrhage have also been observed with balloon IOL.

IOL using a single or double balloon catheter typically involves removal of the catheter approximately 12 hours after insertion, followed by an artificial rupture of membranes (ARM) and commencement of an oxytocin infusion.  Whilst there is good data supporting its efficacy in ripening the cervix, there is limited information to guide exactly how long a balloon catheter should remain in situ.  The product recommendation states “up to 12 hours”.  There are just two abstracts reporting on small clinical trials comparing a 6-hour versus 12-hour insertion.  The methods do not describe how the IOL was managed following removal of the balloon.  These data are under-powered but nevertheless reassuring that an earlier removal of the balloon catheter is likely associated with a shorter duration of labour and is unlikely to be associated with a difference in mode of birth.  There is evidence to support that a longer duration of induced labour is associated with both a poorer healthcare experience and increased costs.   Hence earlier removal of the balloon catheter shows promise as a method to reduce cost, and improve the healthcare experience for women without altering clinical outcomes.   

This study therefore aims to explore the clinical effectiveness and healthcare experience of women undergoing an IOL using a balloon catheter where the balloon is left in-situ for a shorter versus longer duration of time.

Trial website

Trial related presentations / publications

Public notes

Contacts

Principal investigator

Name

A/Prof Michael Beckmann

Address

Level 6
Duncombe Building
Mater Health
Raymond Tce
South Brisbane, QLD, 4101

Country

Australia

Phone

+61731638602

Fax

[email protected]

Contact person for public queries

Name

Michael Beckmann

Address

Level 6
Duncombe Building
Mater Health
Raymond Tce
South Brisbane, QLD, 4101

Country

Australia

Phone

+61731638602

Fax

[email protected]

Contact person for scientific queries

Name

Michael Beckmann

Address

Level 6
Duncombe Building
Mater Health
Raymond Tce
South Brisbane, QLD, 4101

Country

Australia

Phone

+61731638602

Fax

[email protected]

Data sharing statement

Will individual participant data (IPD) for this trial be available (including data dictionaries)?

No/undecided IPD sharing reason/comment

Ethics approval has not been sought

What supporting documents are/will be available?

No Supporting Document Provided

Results publications and other study-related documents

Documents added manually

No documents have been uploaded by study researchers.

Documents added automatically

Source	Title	Year of Publication	DOI
Embase	Mechanical methods for induction of labour.	2019	https://dx.doi.org/10.1002/14651858.CD001233.pub3

N.B. These documents automatically identified may not have been verified by the study sponsor.

Trial Review

Documents added manually

Documents added automatically