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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Date data sharing statement initially provided
Date results information initially provided
Type of registration
Prospectively registered

Titles & IDs
Public title
Pelvic floor assessment in post-partum women
Scientific title
Symptomatic and physiological consequences of obstetric anal sphincter injury in post-partum females
Secondary ID [1] 288626 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Fecal incontinence in post-partum women 297783 0
Obstetric anal sphincter injury syndrome (OASIS) 297828 0
Condition category
Condition code
Oral and Gastrointestinal 297966 297966 0 0
Other diseases of the mouth, teeth, oesophagus, digestive system including liver and colon
Reproductive Health and Childbirth 297967 297967 0 0
Childbirth and postnatal care

Study type
Patient registry
Target follow-up duration
Target follow-up type
Description of intervention(s) / exposure
All participants will be asked to complete a follow up questionnaire.
Anorectal manometry and anorectal ultrasound is to be performed on patient who are consenting to a repeat study using our standard protocol.
(1) Anorectal manometry. This involves insertion of a thin catheter into your rectum (back passage) while you are lying on your left side on a bed. Pressure measurements are then obtained while you squeeze your anal muscles, while you cough and when you bear down or strain. In addition, a small balloon will be inflated inside your rectum and you will be asked to rate the sensations felt at that time. Lastly, you will be requested to try to expel the balloon over a private toilet and (2) Anorectal ultrasound. This involves insertion of an anorectal ultrasound probe into your rectum (back passage) while you are lying on your left side on a bed. Imaging is obtained assessing for your anal sphincters. Both procedures are performed by a physician or a nurse specialist and will be done discretely and with consideration for your privacy at all times. The procedures can cause minor discomfort, but this will be minimised by careful technique. Overall the appointment time is approximately 60 minutes.
The patients invited to participate in this study have previously attended our neurogastroenterology unit for testing between 2001 and 2015. Our follow-up data will consequently offer a follow-up period between 1-15 years.
For ARM testing, the testing protocol is identical to the testing protocol the patients have previously undergone in our Unit. For the anorectal ultrasound, as not all patients have performed this study previously in our Unit, our protocol might be slightly different then the procedure they had previously undergone. Nevertheless, the protocol follows international standards and should be much similiar.
Intervention code [1] 294031 0
Diagnosis / Prognosis
Comparator / control treatment
No control groups
Control group

Primary outcome [1] 297489 0
The development of faecal incontinence in previously asymptomatic post-obstetric women with anal sphincter tear. This will be assessed by long term follow up Faecal incontinence severity index (FISI)
Timepoint [1] 297489 0
Patients selected have already completed an anorectal study within our unit at the request of their obstetrician/physician/surgeon between 2001 and 2015. They are invited to complete a follow-up study (identical protocol) to compare data/outcome for this study, hence the follow-up period is anywhere between 1 to 15 years.
Primary outcome [2] 297517 0
The time-related changes in anorectal physiology following OASIS. This will be assessed by the comparing the anorectal physiology parameters (anal pressures) after childbirth to long-term repeated testing.
Timepoint [2] 297517 0
1-15 years following initial assessment
Primary outcome [3] 297518 0
Single component outcome of subsequent birth history(inclduing repeat OASIS) following previous OASIS. This will be assessed by follow up questionnaires specifically designed for the study and access to ObstetriX to obtain the mode and complications of subsequent deliveries.
Timepoint [3] 297518 0
1-15 years following initial assessment
Secondary outcome [1] 321191 0
Change in quality of life following OASIS. This will be assessed by QOL of life questionnaires (SF36, VAS scores)
Timepoint [1] 321191 0
1-15 years following initial assessment
Secondary outcome [2] 321491 0
Outcome in sexual function as assessed by the Sexual Function for Women with: POP, Urinary Incontinence and/or Fecal Incontinence questionnaire.
Timepoint [2] 321491 0
1-15 years following initial assessment

Key inclusion criteria
Post-partum females referred to the Neurogastroenterology Unit for anorectal manometry between 1.1.2001 and 1.1.2016

Minimum age
18 Years
Maximum age
45 Years
Can healthy volunteers participate?
Key exclusion criteria
The only exclusion criterion for the study includes patients with a history of psychological illness or condition such as to interfere with the patient’s ability to understand the requirements of the study.

Only for patients who agree to undergo repeat physiological testing, exclusion criteria include:
1. Women lactating or pregnant.
2. Patients with significant anorectal disease precluding the insertion of an anorectal tube or ultrasound probe.
3. Latex allergy

Study design
Statistical methods / analysis
We will review 450 patients overall, so that we can realistically obtain the 150 patients required to reach statistical power.

9.1 Sample Size Estimation
Aim 1: For quantitative measures a sample of n=144 would provide statistical power of 0.8 and the 0.05 (two-tailed) level of statistical significance for a Cohen’s d effect size of 0.5 (moderate effect size). For qualitative measures a sample of n=92 would provide statistical power of 0.8 and the 0.05 (two-tailed) level of statistical significance for an odds ratio of 2.0 from a baseline probability of 0.3 (overall Fecal Incontinence rate in this group is approximately 1/3).
Aim 2: In aim 2, based entire on unconditional logistic regression (see below), there is an additional consideration of correlation between potential predictors. Defining the minimum clinically important effect size as an odds ratio of 2.0 and assuming a baseline rate of 15%, to allow for a correlation between any predictor and other predictors of 0.3 increases the required sample size from 92 to 149.

Based on this consideration of samples size per aim the expected available sample size (n=150) should exceed the required sample size for all statistical analyses.

9.2 Statistical Analysis Plan
Aim 1: Among women who have undergone Anorectal manometry those who develop Fecal Incontinence will be compared with those who have not developed Fecal Incontinence with respect to quantitative parameters using the Mann-Whitney test and with respect to qualitative parameters via the Pearson Chi-Square test. A nonparametric approach will be adopted due to the expected non-Normal distribution of a number of the quantitative parameters. Identification of statistically independent discriminators of women who develop Fecal Incontinence from those who do not will be via backward elimination within unconditional logistic regression.
Aim 2: All quantitative and qualitative measures utilised in aims 1 which were recorded at the time of OASIS (Obstetric anal sphincter injury syndrome) will be considered as potentially predictive of the development of subsequent pelvic floor complications. The probability of development of pelvic floor complications will be modelled using unconditional logistic regression with predictive variables selected by backward elimination to ensure the full covariance structure of the predictors is taken into account. To protect against the over-optimism phenomenon to which model selection procedures are prone the selection process will itself be bootstrapped (2000 replications) and only predictive measures that are selected in at least 50% of bootstrap samples will be considered in the final predictive model.

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)
Recruitment hospital [1] 5351 0
Royal North Shore Hospital - St Leonards
Recruitment postcode(s) [1] 12805 0
2065 - Royal North Shore Hospital

Funding & Sponsors
Funding source category [1] 292985 0
Self funded/Unfunded
Name [1] 292985 0
Dr Allison Malcolm Research Fund
Address [1] 292985 0
Royal North Shore Hospital
Reserve Road
St-Leonards, NSW 2065
Country [1] 292985 0
Primary sponsor type
Dr Allison Malcolm
Royal North Shore Hospital
Neurogastroenterology Unit
Reserve Road
St-Leonards, NSW 2065
Secondary sponsor category [1] 291756 0
Name [1] 291756 0
Address [1] 291756 0
Country [1] 291756 0

Ethics approval
Ethics application status
Ethics committee name [1] 294494 0
Northern Sydney Local Health District
Ethics committee address [1] 294494 0
Research Office
Kolling building, level 13
Royal North Shore Hospital
Reserve Road
St-Leonards, NSW 2065
Ethics committee country [1] 294494 0
Date submitted for ethics approval [1] 294494 0
Approval date [1] 294494 0
Ethics approval number [1] 294494 0

Brief summary
Obstetric anal sphincter injury syndrome (OASIS) is a common occurrence in females after childbirth, and is an established risk factor for faecal incontinence (FI). Risk factors for OASIS include increased maternal age, high birth-weight and co-morbidities such as diabetes. As each of these elements is on the rise, the likelihood is that the frequency of OASIS will increase, and along with it, the possible increased burden FI. However, its association with the development of FI remains poorly understood and the obstetrics recommendation following OASIS (C-section vs vaginal delivery) on subsequent pregnancies is highly variable and debated in the literature.

We aim to assess the anorectal physiology effect of OASIS, as well as its impact on the patient (Sexual health, quality of life, urinary and faecal incontinence) to first obtain a better understanding of OASIS. We will then compare the data of patients who develop FI (symptomatic) to those who do not (asymptomatic) in an effort to better understand OASIS and its link to FI. Lastly, we aim to collect long term follow up data on patients in order to assess for the subsequent development of FI and other pelvic floor problems. This will enable us to build a prediction model to assist in clarifying the obstetrician’s practice and recommendations for future pregnancies in women with OASIS and/or FI.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 63906 0
Dr Allison Malcolm
Address 63906 0
Royal North Shore Hospital
Neurogastroenterology Unit
Reserve Road
St-Leonards, NSW 2065
Country 63906 0
Phone 63906 0
Fax 63906 0
Email 63906 0
Contact person for public queries
Name 63907 0
Dr Allison Malcolm
Address 63907 0
Royal North Shore Hospital
Neurogastroenterology Unit
Reserve Road
St-Leonards, NSW 2065
Country 63907 0
Phone 63907 0
Fax 63907 0
Email 63907 0
Contact person for scientific queries
Name 63908 0
Dr Allison Malcolm
Address 63908 0
Royal North Shore Hospital
Neurogastroenterology Unit
Reserve Road
St-Leonards, NSW 2065
Country 63908 0
Phone 63908 0
Fax 63908 0
Email 63908 0

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No/undecided IPD sharing reason/comment
As per ethics approval, raw data will only be accessible by the investigators
What supporting documents are/will be available?
No other documents available
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – plain English summary
A rise in the prevalence of faecal incontinence was noted on long-term follow up (20 to 25%). However, a large number of patients were noted to cross-over between the groups either becoming asymptomatic or developing faecal incontinence.
Fourth degree tears and older the mother at time of developing a tear during delivery were the only obstetric factors associated with the development of faecal incontinence in the long-term. Birth weight, epidural, induction, vacuum/forceps delivery or episiotomy were not.
Some abnormal results on anorectal manometry performed initially, were likely to predict the occurrence/persistence of faecal incontinence on follow up.