A Prospective Observational Study Evaluating the Sonographic Appearance of the Anal Sphincter in Women With Perineal Wound Infection Following Vaginal Delivery.
Conditions: Obstetric Trauma, Perineum; Injury, Perineal Infection, Anal Sphincter Injury
Sponsor: Croydon Health Services NHS Trust

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Protocol: 
 
 
Study Title: 
 
The effect of perineal wound infection on the anal sphincter  
 
 
 
 
 
 
 
A prospective observational study evaluating the sonographic appearance of the anal 
sphincter in postpartum women with perineal wound infection. 
 
 
 
 
 
 
 
 
 
 
 
Chief Investigator: 
Mr Abdul H Sultan, MD FRCOG 
Consultant Obstetrician & Gynaecologist 
Croydon Health Services 
530 London Road, CR7 7YE  
Croydon, United Kingdom 
Telephone number: 020 8401 3000  
 
 
 

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Clinical Investigation Plan Synopsis 
 
Study Title 
A prospective observational study evaluating the sonographic appearance of the 
anal sphincter in postpartum women with perineal wound infection. 
 
IRAS Number 
278466 
Study Design 
Prospective observational study 
Study Participants 
Women referred to the Croydon University Hospital perineal clinic with perineal 
wound infection following vaginal delivery 
Planned Sample 
Size 
80 (seen in year and patients agreeing to participate and exclusion criteria) 
Planned Study 
Period 
Until wound healed 
 
Objectives 
Primary 
 
To investigate the clinical progression of perineal wound infection  
 
Secondary 
 
1. To investigate whether perineal wound infection can extend to involve an 
intact anal sphincter  
2. To investigate the integrity of the anal sphincter in women with a repaired 
obstetric anal sphincter injury and perineal wound infection.  
Inclusion Criteria 
- 
Women with childbirth related perineal injury/episiotomy and wound 
infection 
- 
Women over 18 years of age 
- 
Ability to understand and read the patient information sheet (in English) 
- 
Ability to give informed consent 
Exclusion Criteria 
- 
Vulnerable Adult 
- 
Fetal or neonatal death or poor neonatal outcome 
- 
Women who are in an immunosuppressive state (e.g human 
immunodeficiency virus or pharmacologically induced immunodeficiencies 
by chemotherapy or steroids) 
- 
Inability to give consent 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

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TABLE OF CONTENTS 
 
 
1.INTRODUCTION........................................................................................ 
 
2. STUDY HYPOTHESIS, AIMS AND OBJECTIVES ...................................... 
 
3. CLINICAL INVESTIGATOR AND INVESTIGATION ADMINISTRATIVE  
STRUCTURE................................................................................................. 
3.1 Investigation Site Staff………………………………………………………. 
 
4. METHODOLOGY…………………………….......................................... 
4.1 Overall Design…………………………………………………………………. 
4.2 Procedures and Assessment ……………………………. 
4.3 Selection of Population for Investigation.............................................. 
4.3.1  Inclusion Criteria ........................................................................ 
4.3.2  Exclusion Criteria....................................................................... 
     4.3.3  Participant Withdrawal from Treatment or Assessment.............. 
 
4.4  Data Quality Assurance............................................................................  
4.7.1  Training of Staff .............................................................................  
4.7.2  Data Management .......................................................................  
 
4.5 Statistical Methods and Determination of Sample Size.........................  
4.8.1  Statistical Evaluation....................................................................  
4.8.2  Determination of Sample Size......................................................  
 
5. STATEMENTS OF COMPLIANCE …………………………………………….. 
5.1 Ethics …………………………………………………………………………. 
5.1.1 Ethics and Regulatory Considerations………………………… 
5.1.2 Patient Information and Consent Form …………………………… 
. 
5.2 Regulatory and standards ...................................................................... 
5.2.1  Standards and other.....................................................................  
5.2.2  Subject Data Protection ..............................................................  
 
6. INVESTIGATION TIMETABLE AND TERMINATION .................................. 
 
7. LITERATURE REVIEW AND REFERENCES .............................................. 
 
 

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1. INTRODUCTION 
 
In the United Kingdom (UK), 85% of women sustain perineal injury following a vaginal 
delivery, which accounts for over 350,000 women annually. Injury is either spontaneous, 
iatrogenic following episiotomy or a combination of the two, with 69% of these wounds 
subsequently requiring surgical repair (suturing)(1,2).  
 
The perineum can be divided into two parts; the urogenital triangle which contains the 
external genital organs and the anal triangle containing the anal sphincter and canal(3). 
Spontaneous perineal injury can therefore be classified as shown below in Table 1. This 
differentiation to be made between injuries which involve external anal sphincter (EAS), 
internal anal sphincter (IAS) and anal mucosa(4). 
Degree 
Injury 
First 
Skin only 
Second 
Perineal muscles but not involving the anal sphincter 
Third 
Anal sphincter complex 
3a- less than 50% of the external anal sphincter 
3b- more than 50% of the external anal sphincter 
3c- internal anal sphincter torn 
Fourth 
Anal sphincter complex and anal mucosa 
 
Perineal injury following childbirth can however result in complications such as wound 
infection. Signs and symptoms associated with perineal wound infection including, 
increasing pain, swelling, erythema, excessive or offensive discharge, fever and wound 
dehiscence(5). Croydon Health Services has its own dedicated perineal clinic to manage 
women with perineal wound complications following childbirth. The incidence of perineal 
wound infection between January 2016 to September 2017 was 22.6%(6). In addition, in 
2019, 120 women attended perineal clinic for review and management of symptoms 
suggesting perineal wound infection. 
 
Endoanal ultrasound has been shown to be useful in the assessment of obstetric anal 
sphincter injury (OASI)(7). The anal sphincter can also be visualised using multiplanar 
transperineal ultrasound(three/four-dimensional)(8). However, the natural history and 
integrity of the anal sphincter in women with OASI and wound infection has never been 
evaluated.  
 
In addition, wound infection can extend to affect deeper tissues (9).  It is not known whether 
this infection can infiltrate an intact anal sphincter.  
 

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Understanding the natural history of perineal wound infections would enable appropriate 
interventions prior to the development of complications such as anal incontinence. 
 
2. STUDY HYPOTHESIS, AIMS AND OBJECTIVES 
 
Aim 
To evaluate the sonographic appearance of the anal sphincter complex in women with 
perineal wound infections using three-dimensional (3D) endoanal ultrasound. 
 
Objectives 
Primary:  
To investigate the clinical progression of perineal wound infection  
 
Secondary:  
3. To investigate whether perineal wound infection can extend to involve an intact anal 
sphincter  
4. To investigate the integrity of the anal sphincter in women with repaired obstetric anal 
sphincter injury who sustain perineal wound infection.  
 
 
3. 
CLINICAL 
INVESTIGATORS 
AND 
INVESTIGATION 
ADMINISTRATIVE  
STRUCTURE 
3.1 Investigation Site Staff 
 
CHIEF INVESTIGATOR 
Mr Abdul H Sultan, MBChB, MD FRCOG 
Consultant Obstetrician & Gynaecologist 
Croydon Health Services 
530 London Road, CR7 7YE  
Croydon, United Kingdom 
 
INVESTIGATORS 
Miss Ranee Thakar, MB.BS, MD, FRCOG 
Consultant Obstetrician and Gynaecologist, Subspecialist 
in Urogynaecology 
Croydon Health Services 
530 London Road, CR7 7YE  
Croydon, United Kingdom 
 
 
Dr Nicola Okeahialam, MBChB 
Clinical Research Fellow to Mr Sultan and Miss Thakar 
Croydon Health Services 
530 London Road, CR7 7YE  
Croydon, United Kingdom 
 

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4. METHODOLOGY 
4.1 Overall Design 
This is a single prospective observational study to assess the appearance of the anal sphincter 
complex in women with wound infection following childbirth related perineal injury using (3D) 
endoanal ultrasound or multi-planar transperineal ultrasound(3D/4D). 
 
All patients who have been referred to the Croydon University Hospital dedicated perineal 
clinic with perineal wound infection will be invited to participate. All patients will be given a 
patient information sheet describing the study prior to consent. Patients will be given time to 
read the information included and time to discuss with relatives, colleagues and carers. In 
addition, time to ask the recruiter any questions that have arisen after reading the consent 
form. Informed consent will be obtained. Patients will be assessed at weekly intervals until the 
wound infection has resolved and the wound has clinically healed.  At follow-up all patients 
will complete a case report form, have a vaginal, perineal and rectal examination. Following 
this, the wound will be photographed with the MolecuLight i:X Imaging Device: a portable, 
non-invasive, real-time camera used to depict the bacterial load of a wound. In addition, in 
perineal wounds that have superficially dehisced, wound healing progression will be mapped 
using the Silhouette® 3D camera: an imaging device that precisely and consistently measures 
the area, depth, volume of wounds and their healing progress. Finally, an endoanal ultrasound 
scan and/or transperineal ultrasound will be performed.  
 
4.2 Procedures and Assessment 
Patient data, history and physical examination:  
As per standard procedure for the Croydon Health Services Perineal Clinic. Demographic and 
obstetric data will be collected prospectively from the maternity notes, including: maternal age, 
gestational age at delivery, parity, body mass index, duration of first and second stage of 
labour, indication for operative vaginal delivery, mode of delivery, mediolateral episiotomy, 
and neonatal weight. In addition, information in regards to the repair of the perineal injury 
including suture type, place of repair and grade of repairer.  Presenting symptoms review, 
medical history, use of medications including antibiotics for wound infection will be obtained 
at baseline. Women will have a vaginal, perineal and rectal examination prior to ultrasound 
scan. This be recorded on the case report form.  
All datasets will be coded and anonymised. The data will be stored in a secure room within 
the Trust. All electronic data will be stored within password protected IT system within the 
Trust, which is only accessible by the clinical and research team. 
 
Endoanal Ultrasound 

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Endoanal ultrasound will be performed with the BK Flexfocus 400 (Gentofte, Denmark) fitted 
with a 12 - 16 MHz anorectal transducer (type 2050; focal point up to 20 mm and focal range 
5 - 45 mm). Patients will be scanned in the left lateral position, with the endoanal probe 
along the axis of the anal canal.  
 
Anal sphincter defects will be scored using a validated Starck score which accounts for 
depth, length and size of the defect for both internal and external anal sphincter, with a 
range from 0 being no defect to 16 being maximal defect.  
 
Transperineal Ultrasound 
If endoanal ultrasound is declined or not tolerated, the anal sphincter will also be assessed 
using three-/four-dimensional (3D/4D) transperineal ultrasound using a Voluson 730 Expert 
or Voluson S6 systems with a RAB 8–4-MHz transducer (GE Medical Systems, Zipf, Austria) 
with the probe placed externally on the area of the fourchette. Patients will be scanned in a 
dorsal lithotomy position with hips in a flexed and slightly abducted position. Advantages of 
this form of ultrasound include acceptability by patients as it is painless and non-
intrusive(7,8). 
 
Microbiological assessment: 
If a wound swab has not been taken prior to referral or wound swab results are not available, 
one will be taken to detect the causative organisms. Appropriate antibiotics will then be given 
to cover the detected organism. 
 
The Silhouette® 3D camera: 
For wound that have superficially dehisced, the wound surface area, depth, volume and 
healing progress will be precisely measured using the Silhouette® 3D camera. This is a 
system that uses 3D laser technology to track wound healing progression.  
 
The MolecuLight i:X:  
The bacterial load of the perineal wound will be measured every week using the 
MolecuLight i:X. This is a system, which uses fluorescent illumination to capture and 
document the presence of bacteria. The fluorescence images obtained have distinct colours, 
which are associated with bacteria and other different wound aspects (Table 1). These 
findings will be supported by microbiological analysis of the wound with swab culture and 
sensitivity. 
 
 

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Table 1: 
Red 
Presence of potentially harmful levels of bacteria 
Green 
Connective tissues in skin 
Dark/black 
areas  
 
Blood, highly vascularized tissues, necrotic tissue, highly pigmented 
tissue (freckles, moles, etc.) or poorly illuminated areas 
White  
 
Materials in the field of view that are white (bed sheet, clothing, paper, 
wound measuring ruler, etc.) or oversaturation of color signal 
Cyan 
Presence of Pseudomonas aeruginosa 
 
Statistical analysis 
Statistical analysis will be performed using SPSS version 20.0 or higher. 
 
4.3 Selection of Population for Investigation  
4.3.1  Inclusion Criteria: 
- 
Women with childbirth related perineal injury and wound infection 
- 
Women over 18 years of age 
- 
Ability to understand and read the patient information sheet (in English) 
- 
Ability to give informed consent 
 
4.3.2 Exclusion criteria: 
- 
Vulnerable Adult 
- 
Fetal or neonatal death or poor neonatal outcome 
- 
Women who are in an immunosuppressive state (e.g human immunodeficiency virus 
or pharmacologically induced immunodeficiencies by chemotherapy or steroids) 
- 
Inability to give consent 
 
4.3.3   Participants Withdrawal from Treatment or Assessment 
Participants are free to withdraw from the study at any time, and without any effect to their 
routine care.  
 
4.4 Data Quality Assurance 
4.4.1 Training of Staff  
The chief investigator will ensure that the site staff has received appropriate training in the 
following: 
• 
The Clinical Investigation Plan and execution of it 
• 
Maintenance of the Investigator Site File 
 
4.7.2  Data Management 

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Data entry will be completed by the research team on site. The data will be transferred to an 
electronic format and encrypted onto an external hard drive, which will be kept in a locked 
office cabinet. 
 
As missing data has the potential to cause bias and so nullify study findings, every effort will 
be made by the site staff to will minimize and ensure there is no incomplete or missing data. 
All data collected will be inspected by site staff to identify missing data and outliers. If this 
problem however was to arise, the biostatistics team will also aid us with incomplete-data 
analysis strategies in order to come to appropriate, robust conclusions.  
 
We will store research data generated by the study for 5 years. 
 
Research findings will be disseminated for publications in peer- reviewed journals, 
presentations at professional meetings/conferences. If requested results will also be 
disseminated research participants and other interested groups or communities in a written 
format. 
 
 
4.5 Statistical Methods and Determination of Sample Size 
The sample size enrolled will be 80.  This was calculated with reference to the number of 
women attending the Croydon University Hospital dedicated perineal clinic in 2019; 120 
women. Taking into account women meeting the inclusion and exclusion criteria. In addition, 
women declining to participate. 
 
 
5. STATEMENTS OF COMPLIANCE 
5.1.1 Ethics and Regulatory Considerations  
 
Declaration of Helsinki 
The Investigators will ensure that this study is completed in compliance with the ethical 
principles of the Declaration of Helsinki. 
Good Clinical Practice 
The Investigator will ensure that this study is completed in compliance with Good Clinical 
Practice guidance and applicable regulatory requirement(s). The Investigator will submit 
and, where necessary, obtain approval from the above parties for all substantial 
amendments to the original approved documents. 

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Participant Confidentiality 
The Investigators will ensure that the participants’ anonymity is maintained to protect their 
confidentiality and privacy. Data will be anonymised, in keeping with the Data Protection Act. 
Documents will be stored securely and only accessible by investigators and authorised 
personnel. 
 
 
5.1.2 Patient Information and Consent Form 
All patients will be given a patient information sheet describing the study prior to consent.  This 
includes the study nature, purpose and possible risks and benefits. Patients will be given 
adequate time to read the information including and time to discuss with relatives, colleagues 
and carers. In addition, time to ask the recruiter any questions that have arisen after reading 
the consent form. Participants will be informed that they are free to withdraw from the study at 
any time, and without any effect to their routine care. 
The participants signed consent form must be obtained before conduction of any investigation. 
A copy of the Patient Information Sheet including the signed Consent Form should be given 
to the subject.  
 
5.2 Regulatory and standards 
5.2.1  Standards and other 
• 
Guideline for good clinical practice E6(R2) 
• 
GDPR 
 
5.2.2  Subject Data Protection 
The written patient information sheet follows the GDPR requirements for transparency. It 
explains that health records will remain strictly confidential at all times in accordance with the 
Caldicott principles and the Data Protection Act 1998. All information collected will be coded 
for anonymisation with the link document locked and kept separately from the data. The 
coded data would be stored on NHS computers only and password protected with access to 
authorised researchers only. 
 
 

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References: 
1.  McCandlish R, Bowler U, Asten H, Berridge G, Winter C, Sames L, et al. A randomised 
controlled trial of care of the perineum during second stage of normal labour. BJOG:An 
international journal of O&G. 1998 Dec;105(12):1262–72.  
2.  Royal College of Obstetricians and Gynaecologists (RCOG). Methods and Materials 
used in Perineal repair, Guideline No 23. London: Royal College of Obstetricians and 
Gynaecologists Press; 2004.  
3.  Thakar R, Fenner DE. Anatomy of the Perineum and the Anal Sphincter. In: Sultan AH, 
Thakar R, Fenner DE, editors. Perineal and Anal Sphincter Trauma: Diagnosis and 
Clinical Management [Internet]. London: Springer London; 2007. p. 1–12. Available from: 
https://doi.org/10.1007/978-1-84628-503-5_1 
4.  Sultan AH. Obstetric Perineal Injury and Anal Incontinence. AVMA Medical & Legal 
Journal. 1999 Nov;5(6):193–6.  
5.  Webb S, Sherburn M, Ismail KMK. Managing perineal trauma after childbirth. BMJ. 2014 
Nov 25;349(nov25 27):g6829–g6829.  
6.  Arendsen L, Thakar R, Sultan A. Can perineal wound infection following vagina delivery 
be reduced? A double blind randomised controlled trial using copper impregnated 
maternity sanitary towels. European Journal of Obstetrics & Gynecology and 
Reproductive Biology. 2019 Mar;234:e180.  
7.  Taithongchai A, van Gruting IMA, Volløyhaug I, Arendsen LP, Sultan AH, Thakar R. 
Comparing the diagnostic accuracy of 3 ultrasound modalities for diagnosing obstetric 
anal sphincter injuries. American Journal of Obstetrics and Gynecology. 2019 
Aug;221(2):134.e1-134.e9.  
8.  Eisenberg VH, Valsky DV, Yagel S. Transperineal ultrasound assessment of the anal 
sphincter after obstetric anal sphincter injury (OASI). Ultrasound Obstet Gynecol. 2019 
Feb;53(2):158–65.  
9.  European Centre for Disease Prevention and Control. Stockholm. Surgical site 
infections. In:ECDC. Annual epidemiological report for 2017. 2019.