Evaluation of the Rectal Reflex Using Anal Acoustic Reflectometry

Anal Acoustic Reflectometry (AAR) is a reliable and reproducible technique that has been studied in our department over the last 6 years. Sound waves pass into a balloon placed in the anal canal and are used to measure the cross-sectional area. By gradually increasing and decreasing the pressure in the balloon the investigators can measure the pressure at which the cross-sectional area starts to increase and decrease, and the anal canal starts to open and close. This assessment mimics the natural opening and closing of the anal canal and the effect of squeezing the muscles.

The gold standard investigation of the anal sphincter muscles has been manometry which measures anal canal pressure at rest and during squeeze. However, it has limitations. In previous studies AAR has shown promise in the assessment of faecal incontinence and, that unlike manometry, it has been able to distinguish between different types of incontinence.

The Recto-anal Inhibitory Reflex (RAIR) is a normal response when the rectum fills with faeces, fluid or air, whereby there is a change in the pressures within the anal canal to determine the type of contents. This can be absent or altered in patients who have difficulty in opening their bowels. The RAIR is currently measured by anal manometry using a 4.9mm catheter, resulting in an anal canal which is already partially opened prior to the measurement, and potentially distorted.

AAR is considered a catheter free technique as the balloon has a cross-sectional area of only 0.4mm2 when collapsed. The investigators propose to measure the RAIR using a 1.7mm diameter catheter alongside the AAR balloon to determine the effect that its placement has on the recorded parameters of AAR. This aims to improve our understanding of the opening and closing of the anal canal in response to distension of the rectum.

Study Overview

• Status: Completed
• Conditions: Pelvic Floor Dysfunction

• Study Type: Observational
• Enrollment (Actual): 40

Contacts and Locations

Study Locations

• United Kingdom
  • Greater Manchester
    • Manchester, Greater Manchester, United Kingdom, M23 9LT
      • University Hospital of South Manchester

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

• Sampling Method: Non-Probability Sample

Study Population

Patients presenting to the pelvic floor clinic and neurogastroenterology with symptoms of pelvic floor dysfunction

Description

Inclusion Criteria:

1. Adults over 18 years old
2. Have capacity to consent to the study
3. Patients with pelvic floor dysfunction.

Exclusion Criteria:

1. Minors under the age of 18 years old
2. Patients who lack capacity to consent
3. Patients with known rectal tumours and proctitis
4. Asymptomatic patients

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort
Pelvic Floor Dysfunction; Observational study where patients with pelvic floor dysfunction undergo three AAR measurements. One at baseline, one with the catheter alongside and a third with the rectal balloon inflated. No intervention is performed Note, that initial inclusion of Squeeze parameters was detailed in error, these were not compared in this study and were compared in previous study

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Opening Pressure	Measurements of differences in Opening pressure (Op - cm H2O) as measured by the AAR catheter. These measurements are taken at baseline with the rectal balloon collapsed (Pre-RAIR) and after inflation of 100mls air into rectal balloon (Post-RAIR).	during single study visit- measurement taken prior to balloon inflation and post balloon inflation
Opening Elastance	Measurements of differences in Opening Elastance (Oe - cm H2O/mm2) as measured by the AAR catheter. These measurements are taken at baseline with the rectal balloon collapsed (Pre-RAIR) and after inflation of 100mls air into rectal balloon (Post-RAIR).	during single study visit- measurement taken prior to balloon inflation and post balloon inflation
Closing Pressure	Measurements of differences in Closing Pressure (Cp - cm H2O) as measured by the AAR catheter. These measurements are taken at baseline with the rectal balloon collapsed (Pre-RAIR) and after inflation of 100mls air into rectal balloon (Post-RAIR).	during single study visit- measurement taken prior to balloon inflation and post balloon inflation
Closing Elastance	Measurements of differences in Closing Elastance (Ce - cm H2O/mm2) as measured by the AAR catheter. These measurements are taken at baseline with the rectal balloon collapsed (Pre-RAIR) and after inflation of 100mls air into rectal balloon (Post-RAIR).	during single study visit- measurement taken prior to balloon inflation and post balloon inflation
Hysteresis	Measurements of differences in Hysteresis (%) as measured by the AAR catheter. These measurements are taken at baseline with the rectal balloon collapsed (Pre-RAIR) and after inflation of 100mls air into rectal balloon (Post-RAIR). Hysteresis is the extent of energy expenditure during opening and closing of the anal canal and represents the difference between opening and closing pressure and is expressed as a percentage	during single study visit- measurement taken prior to balloon inflation and post balloon inflation

Collaborators and Investigators

• Sponsor: Manchester University NHS Foundation Trust
• Investigators: Study Chair: Karen J Telford, MBChBMDFRCS, University Hospital of South Manchester

Publications and helpful links

General Publications

• Klarskov N, Saaby ML, Lose G. A faster urethral pressure reflectometry technique for evaluating the squeezing function. Scand J Urol. 2013 Dec;47(6):529-33. doi: 10.3109/21681805.2013.776629. Epub 2013 Mar 19.
• Hornung BR, Mitchell PJ, Carlson GL, Klarskov N, Lose G, Kiff ES. Comparative study of anal acoustic reflectometry and anal manometry in the assessment of faecal incontinence. Br J Surg. 2012 Dec;99(12):1718-24. doi: 10.1002/bjs.8943. Erratum In: Br J Surg. 2013 Jan;100(2):301.
• Mitchell PJ, Klarskov N, Telford KJ, Hosker GL, Lose G, Kiff ES. Viscoelastic assessment of anal canal function using acoustic reflectometry: a clinically useful technique. Dis Colon Rectum. 2012 Feb;55(2):211-7. doi: 10.1097/DCR.0b013e31823b2499.
• Mitchell PJ, Klarskov N, Telford KJ, Hosker GL, Lose G, Kiff ES. Anal acoustic reflectometry: a new reproducible technique providing physiological assessment of anal sphincter function. Dis Colon Rectum. 2011 Sep;54(9):1122-8. doi: 10.1097/DCR.0b013e318223fbcb.
• Klarskov N. Urethral pressure reflectometry. A method for simultaneous measurements of pressure and cross-sectional area in the female urethra. Dan Med J. 2012 Mar;59(3):B4412.
• Saaby ML, Klarskov N, Lose G. Urethral pressure reflectometry before and after tension-free vaginal tape. Neurourol Urodyn. 2012 Nov;31(8):1231-5. doi: 10.1002/nau.22239. Epub 2012 Mar 27.
• Cheeney G, Nguyen M, Valestin J, Rao SS. Topographic and manometric characterization of the recto-anal inhibitory reflex. Neurogastroenterol Motil. 2012 Mar;24(3):e147-54. doi: 10.1111/j.1365-2982.2011.01857.x. Epub 2012 Jan 11.
• Heywood NA, Sharma A, Kiff ES, Klarskov N, Telford KJ. Placement of a fine-bore rectal balloon catheter in the anal canal does not affect anal sphincter pressures: improving our understanding of physiological function with anal acoustic reflectometry. Colorectal Dis. 2020 Nov;22(11):1626-1631. doi: 10.1111/codi.15300. Epub 2020 Aug 30.
• Heywood NA, Sharma A, Kiff ES, Klarskov N, Telford KJ. A novel method for measurement of the recto-anal inhibitory reflex using anal acoustic reflectometry. Colorectal Dis. 2020 Nov;22(11):1632-1641. doi: 10.1111/codi.15110. Epub 2020 Sep 23.

Study record dates

Study Major Dates

• Study Start (Actual): February 1, 2016
• Primary Completion (Actual): October 1, 2016
• Study Completion (Actual): April 1, 2017

Study Registration Dates

• First Submitted: March 21, 2016
• First Submitted That Met QC Criteria: May 20, 2016
• First Posted (Estimate): May 25, 2016

Study Record Updates

• Last Update Posted (Actual): December 2, 2020
• Last Update Submitted That Met QC Criteria: November 16, 2020
• Last Verified: November 1, 2020

More Information

Terms related to this study

• Keywords: Rectal Prolapse; Faecal Incontinence; Obstructive Defaecation
• Other Study ID Numbers: 2016GA002

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO