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Trans rectal endoscopic ultrasound (TREUS)

Patient information A-Z

Before your appointment

  • Please follow the enclosed bowel preparation instructions carefully. Your bowel must be completely empty to allow the endoscopist to have a clear view.
  • Stop taking iron tablets seven days before the procedure. All other medication (including aspirin) should be taken as normal
  • If you have any questions about the procedure or find that you cannot keep this appointment, please contact the endoscopy office between 09:00 and 17:00 Monday to Friday on 01223 257080.

On the day

  • Follow the bowel preparation instructions in this leaflet carefully because your bowel must be completely empty of waste material to allow the endoscopist to have a clear view of your bowel.
  • You may eat and drink as normal.
  • If you want to have sedation please ensure you have arranged an escort to take you home. We cannot sedate you if you not provide details of your escort

At the hospital

  • Please come to the endoscopy department, on level three of the Addenbrooke’s Treatment Centre (ATC).
  • Use the ‘Car Park 2’. The car park is busy early in the morning; please allow yourself enough time to arrive in time for your appointment. Take your parking ticket to the Endoscopy reception desk to have your ticket stamped; this will enable you to have discounted parking.
  • Please note you need to arrive 30 minutes prior to your appointment time for your pre procedure check. The length of time you will be here will vary enormously but expect it to be anything from two to four hours or more. Please ask your admitting nurse for further information during your admission check.

What is a rectal endoscopic ultrasound?

Illustration of a colonoscopy
Illustration of inside the body including the intestines

Your doctor has requested these procedures to help investigate and manage your medical condition.

Trans Rectal Endoscopic ultrasound (TREUS) is a procedure that combines the ability to examine the lining of the colon as well as what is beneath the surface.

This is done using a special endoscopy/ultrasound scope. This is a long flexible tube (thinner than your little finger) with a light at the end and a built in miniaturised ultrasound probe. It is passed into the rectum to see lower pelvic structures.

Sometimes it is helpful to take a biopsy – a sample of the lining of the rectum. This is done by passing a small instrument called forceps through the endoscope to ‘pinch’ out a tiny bit of the lining (about the size of a pinhead) which is sent to the laboratory for analysis.

The procedure takes about 10 minutes and is usually performed without sedation although this is available if you prefer.

Non-urgent advice: Getting ready for the procedure

Bowel preparation to be completed three hours before leaving home.

If you are unable to administer the enema yourself the nurses will do this for you on the day of the test. Please contact the endoscopy unit the day prior to your appointment to organise your arrival time.

  1. Use the enclosed enema, please read the enclosed instructions.
  2. Lay on your left hand side with your knees bent, you may want to place a towel underneath you.
  3. Remove the tip of the enema nozzle. Insert the nozzle into your anus (back passage) and squeeze in the liquid.
  4. Hold the liquid inside you for as long as possible, preferably 10 to 15 minutes.
  5. After five minutes (or as long as you have been able to hold the enema) go to the toilet and allow the enema liquid to flush away by opening your bowels as usual.

On arrival to the department

Please register your arrival with the receptionist, they will ask for your pre-procedure questionnaire. Some patients may arrive after you but be seen quicker; we have seven procedure rooms all undertaking different procedures therefore patients are not seen in arrival order.

Before your procedure you will meet one of the nurses who will ask you some health questions, explain the procedure to you.

Once this is completed you will be escorted to a single sex changing area. You will be asked to change into a gown and ‘dignity shorts’ ready for the procedure. Your escort cannot wait with you from this point and can leave the department until you are ready to go home.

You can change your mind about having the procedure at any time.


For many people Trans Rectal Ultrasound is only slightly uncomfortable and sedation is not required. The options are:

  1. No sedation: The advantage is that you can leave as soon as the procedure is finished and you have talked to the endoscopist. You may resume your normal activities such as working and driving. You will be fully aware of the procedure; most patients find this acceptable.
  2. Entonox: also known as ‘gas and air’ this is used to stop discomfort during procedures. It provides quick relief and allows you to be in control. You can leave the department after 30 minutes and can continue with your normal activities.
  3. Intravenous sedation: we will give you an injection into a vein to make you feel relaxed and sleepy but not unconscious (this is not a general anaesthetic). This option means you may not be aware of the procedure.

The disadvantages to this option are:

  • You will need to stay whilst you recover which may take up to an hour or more.
  • You will need to be escorted home; your procedure will be cancelled if you do not have an escort.
  • The injection will continue to have a mild sedative effect for up to 24 hours and may leave you unsteady on your feet for a while.

Non-urgent advice: If you choose sedation

If you choose sedation, you must arrange for a responsible adult to collect you from the department and take you home. You will not be able to drive yourself. You cannot be collected in a taxi without your escort present.

Please provide reception with the contact details of your escort, they need to be available to collect you from 90 minutes after your appointment time.

If you are entitled to use hospital transport, an escort is not required. Please inform the department prior to your appointment if you have arranged hospital transport.

What happens during the procedure?

You will be collected from the changing room by the endoscopist and taken to a private bay to complete your consent form, when this has been completed they will escort you to the procedure room.

The team in the procedure room will introduce themselves and ask you some questions; this is to confirm you ready and prepared to continue with the procedure.

We will ask you to remove any glasses and we will make you comfortable on a couch, lying on your left side with your knees bent. For your comfort and reassurance, a trained nurse will stay with you throughout the procedure.

If you are having sedation, the endoscopist will give you the injection and we will give you oxygen through a facemask and a plastic 'peg' will be placed on your finger to monitor your pulse and oxygen levels. If you have chosen entonox the nurse will explain how to use it before the procedure commences.

The endoscopist will gently insert the colonoscope through your anus into your rectum. At this time, you might feel as if you need to go to the toilet. This is perfectly natural reaction and there is no need to worry. There may be periods of discomfort but these are usually mild. If you find the procedure more uncomfortable than you would like, please let the nurse know and we will give you some pain relief.

However, if you make it clear that you are too uncomfortable the procedure will be stopped.

Potential risks

Rectal endoscopic ultrasound procedures carry a very small risk (one in 5,000 cases) of haemorrhage (bleeding) or perforation (tear) to the bowel. Bleeding is usually stopped during the procedure; occasionally, for a patient who bleeds severely a blood transfusion may be necessary. Perforations often heal by themselves but, on rare occasions, an operation is needed which may involve making a temporary opening in the abdomen (called a stoma) to allow the passage of waste. Another rare complication include and an adverse reaction to the intravenous sedative and pain relief medication.

After the procedure

If unsedated, you may go home immediately after the procedure.

If you had entonox, we will take you to recovery and ask you to rest for approximately 30 minutes. We will give you a drink before you get dressed.

If you had sedation, we will take you to a recovery area while the sedation wears off. When you are sufficiently awake, we will give you a drink before you get dressed. You can then go home; this may be up to an hour following the procedure.

We advise you not to drive, operate machinery, return to work, drink alcohol or sign legally binding documents for a 24-hour period after the procedure. We also advise you to have a responsible adult to stay with you for the next 12 hours. You can eat and drink as normal.

You may feel a little bloated and have some wind-like pains because of the air in your gut; these usually settle down quickly.

We will always do our best to respect your privacy and dignity, e.g. with the use of curtains. If you have any concerns, please speak to the department sister or charge nurse.

When will I know the result?

If you did not have sedation the endoscopist or endoscopy nurse will give you information during and immediately after the procedure. If you had sedation, we will tell you about the procedure in the recovery area when you are awake. If you would like more privacy, we will take you to a private room.

The sedation can affect your ability to remember any discussion. If you would like someone with you when you talk to the endoscopist or endoscopy nurse please inform the nurse looking after you who will arrange for you to be seen in a private room with your escort when they arrive.

The final results from biopsies or polyp removals will be given to you either by the healthcare professional who requested the procedure at a clinic appointment or by letter. These results can take several weeks to come through. You should discuss details of these results and any further treatment with that person.

After discharge

If you experience any severe pain or persistent bleeding you should contact your GP informing them that you have had a Trans Rectal Endoscopic ultrasound.

If you are unable to contact your GP: during working hours (08:00-18:00) contact the endoscopy department on 01223 216515, outside of these hours please attend your nearest emergency department.


Due to the unique information obtained from a TREUS there are no real alternatives although in a few instances other radiological tests may give the answers required.

For more information:

Contact the endoscopy office between 09:00 and 17:00 on 01223 257080.

We are smoke-free

Smoking is not allowed anywhere on the hospital campus. For advice and support in quitting, contact your GP or the free NHS stop smoking helpline on 0800 169 0 169.

Other formats

Help accessing this information in other formats is available. To find out more about the services we provide, please visit our patient information help page (see link below) or telephone 01223 256998.

Contact us

Cambridge University Hospitals
NHS Foundation Trust
Hills Road, Cambridge

Telephone +44 (0)1223 245151