Ano-rectal Physiology Investigations – An Investigation for Patients with Bowel Problems

  • Reference Number: HEY-022/2016
  • Departments: GI Physiology


This leaflet has been produced to give you general information about your ano-rectal physiology investigations.  Most of your questions should be answered by this leaflet. It is not intended to replace the discussion between you and your doctor, but may act as a starting point for discussion. If after reading it you have any concerns or require further explanation, please discuss this with a member of the healthcare team caring for you.

What is ano-rectal physiology?

You have probably been troubled by bowel symptoms for example constipation or faecal incontinence. Following discussion with your doctor, they have advised you to have ano-rectal physiology investigations.

Ano-rectal physiology tests are used to assess the muscle and nerve function in the anal canal and rectum in patients with a variety of bowel disorders.

Depending on your symptoms there may be several different tests, these include pressure studies (manometry) which measure the pressure in the anal canal, sensory function, which assesses sensations of the rectum, endo-anal ultrasound, which examines the anatomy of the anal canal muscles and nerve (neurophysiological) testing, which measures the nerves supplying the anal canal and rectum are working correctly.

Why do I need ano-rectal physiology?

Ano-rectal physiology investigations will help your healthcare professional to identify if there are any problems with your anal canal, rectum and the nerves supplying the rectum and anal canal.

Can there be any complications or risks?

Very rarely some patients have experienced minor bleeding such as spotting on the toilet paper. The entrance to your bottom (the anus) does have a very good blood supply and this is where piles can be found, the insertion of the physiology equipment may cause a little bleeding. This usually resolves on its own.

Some of the equipment used during your investigations may contain latex.

Patients who have a latex allergy are asked to inform the department before they attend so we can prepare the examination room.

Ano-rectal investigations are not usually performed within the first three months of pregnancy. Please inform the department so alternative appointment can be arranged.

How do I prepare for ano-rectal physiology?

Please read the information leaflet. Share the information it contains with your partner and family (if you wish) so that they can be of help and support. There may be information they need to know, especially if they are taking care of you following this examination.

You have been sent a glycerine suppository – this is to aid the clearance of your lower bowel prior to the tests. Remove the plastic packaging and insert into the anal canal so it goes into the rectum (lower bowel) – it will take around 15 – 45 minutes to work and should work once. You should aim to use it around 1 hour before your appointment. You should not use the suppository if you are sensitive to glycerine or gelatin or in the first 3 months of pregnancy. You may experience some stomach cramps, which should soon disappear.

You are asked to complete a bowel diary and questionnaire before your appointment. The bowel diary should be completed for 14 days prior to your appointment – if you have a short notice appointment, please complete as many days as possible. The instructions for completion are on the form.

You can eat and drink as normal.

What will happen?

You should go to the Department of GI Physiology, which is situated next to Ward 14 (1st floor) at Castle Hill Hospital.

You will be seen by a member of staff from the Department of GI Physiology who will be performing the ano-rectal physiology investigations in the physiology laboratory.

You will be asked to remove your lower clothing and lay on your left side on the examination couch. The pressure tests involves a thin tube (manometry catheter) being inserted into the anal canal and lower rectum, following which you will be asked to cough, squeeze and push down. This enables an assessment of the strength and coordination of the anal canal muscles. Sensory function can also be assessed while the catheter is in place.

An endo-anal ultrasound is performed within the anal canal, it is used to visualise the muscles in the anal canal. Several images will be taken which allows identification of the muscles of the anal canal.

The nerve testing (if necessary) is performed by wrapping an electrode round the clinicians index finger and then passed into the anal canal and rectum, this test measures the efficiency of the nerves that supply the rectum and anal canal – this test may be slightly uncomfortable but utmost care will be taken to avoid any discomfort.

The tests should be completed within 45 – 50 minutes.

Once your physiology investigations are completed you will be able to get dressed and return to your normal activities.

You will not be sedated for your investigations – you will therefore be able to travel or drive as normal.

What will happen
The above picture demonstrates where the probe will be placed in the anal canal during your test.

What happens afterwards?

You will be able to resume your normal activities after your ano-rectal physiology investigations.

You will be sent an appointment to discuss your results from your referring consultant / healthcare professional.

Should you require further advice on the issues contained in this leaflet, please do not hesitate to contact the Department of GI Physiology on telephone (01482) 624036.

General Advice and Consent

Most of your questions should have been answered by this leaflet, but remember that this is only a starting point for discussion with the healthcare team.

Consent to treatment

Before any doctor, nurse or therapist examines or treats you, they must seek your consent or permission. In order to make a decision, you need to have information from health professionals about the treatment or investigation which is being offered to you. You should always ask them more questions if you do not understand or if you want more information.

The information you receive should be about your condition, the alternatives available to you, and whether it carries risks as well as the benefits. What is important is that your consent is genuine or valid. That means:

  • you must be able to give your consent
  • you must be given enough information to enable you to make a decision
  • you must be acting under your own free will and not under the strong influence of another person

Information about you

We collect and use your information to provide you with care and treatment. As part of your care, information about you will be shared between members of a healthcare team, some of whom you may not meet. Your information may also be used to help train staff, to check the quality of our care, to manage and plan the health service, and to help with research. Wherever possible we use anonymous data.

We may pass on relevant information to other health organisations that provide you with care. All information is treated as strictly confidential and is not given to anyone who does not need it. If you have any concerns please ask your doctor, or the person caring for you.

Under the General Data Protection Regulation and the Data Protection Act 2018 we are responsible for maintaining the confidentiality of any information we hold about you. For further information visit the following page: Confidential Information about You.

If you or your carer needs information about your health and wellbeing and about your care and treatment in a different format, such as large print, braille or audio, due to disability, impairment or sensory loss, please advise a member of staff and this can be arranged.