A Patient's Guide to Having a CT Guided Injection

CT stands for Computed Tomography.

A CT scan is an imaging investigation using X-rays. It is performed on a specialised scanner to produce detailed cross-sectional images of the body enabling diagnosis and follow up of disease and injury. 

The CT scanner comprises of a doughnut shaped gantry and motorised bed. Contained within the gantry is an X-ray tube and row of detectors. As the bed slowly moves through the gantry the X-ray tube rapidly rotates and a narrow beam of X-rays passes through the body. As the X-rays leave the body, they are picked up by the detectors and information is sent to a computer. The computer converts the information into an image which can be viewed as either a separate slice or a number of slices combined together to form a 3D image.

A CT guided injection is the accurate placement of a very thin needle directly into a joint or to the path of the small nerve which supplies sensation to a joint, using CT guidance. Once the needle is in the correct position, medication is administered. The injections are usually performed to treat pain; however, can be used for diagnostic purposes also. CT guided injections normally take between 20 minutes and 60 minutes.

In order to obtain your consent, the radiographer and radiologist performing your procedure will need to ask you some questions. The radiologist will explain what they are going to do and explain the benefits and risks associated with the procedure. Please do not hesitate to ask any questions you may have. By giving your consent you are confirming that you understand what the procedure involves and that you are agreeing to have the scan.

Please wear loose, comfortable clothing.

You may be asked to change into a hospital gown if there is any metal on your clothing.

Zips, clips, buttons, belts, underwire, adjustable straps, hooks and eyes will show up on the images and reduce the image quality.

You will also be asked to remove any jewellery, hair accessories, metal plated dentures, hearing aids, coins, phones and wallets if they are situated around the area of the body being scanned.

If any of the following apply to you, please call the Scanning Department on Telephone: 0208 909 5801

• If you are taking Anti-coagulants (blood thinning medications) such as Aspirin, Warfarin, Apixaban, Clopidgrel or Rivaroxaban (These medications may need to be temporarily stopped before the procedure)
• If you are taking or have recently been taking Antibiotics
• If you are allergic to any medications
• If you have an infection or have recently had an infection

(Your appointment could be cancelled if you do not contact the department prior to your appointment).

Please continue to take any other medication as advised by your doctor.

The radiographer will positon you on the bed. Straps and pillows are occasionally used to support you during the procedure.

Once positioned, the radiographer will leave the room. They will be able to see you through the glass window and you can speak to them through the intercom system. Limited planning CT scans are carried out.

The radiologist will use the planning scans to locate the precise area to insert the needle. A small black dot may be drawn onto your skin using a marker pen.

The radiologist will clean your skin and place a sterile drape around the area to be injected.

Local anaesthetic will be administered to numb the area and once it has taken effect, the radiologist will start inserting the needle.

CT guidance will be used until the needle is in the correct position and then the medication is administered.

The needle is then removed and a small dressing placed onto your skin.

It is extremely important that you keep your whole body very still throughout the procedure. Any movement can affect the position of the needle and cause blurring of the images.

The radiographer will take you off the bed and the radiologist will check that you are feeling well enough to leave the department.

You will be given a pain diary, a pre-paid envelope and an aftercare sheet.

Once you have completed your pain diary, please return it in the prepaid envelope provided.

A CT scan can be harmful to an unborn baby. If you are, or think you may be pregnant you must inform the radiographer. The radiographer will also check your pregnancy status prior to the scan.

A CT scan uses X-rays. This is a type of radiation known as ionising radiation. The level of radiation you get from a medical X-ray examination is very low and the associated risks are minimal. The radiographers are trained to ensure that the level of radiation you receive is as low as practicable and the benefits of having the scan are thought to outweigh any risks.

With any interventional procedure, there are risks and side effects.

Risks include: infection, bleeding, worsening of symptoms and allergic reaction.

Side effects include: numbness and temporary discomfort in the area injected.

Please inform the radiologist or radiographer if you begin to feel unwell during the procedure.

If you think you are pregnant, are taking anti-coagulants or antibiotics or you are allergic to any medications you must inform your doctor. Alternatively, if you have any questions or would like to discuss any issues further please do not hesitate to call the Scanning Department on Telephone: 020 8909 5801 Monday to Friday between the hours of 09:00 and 17:00.

Your referring doctor has decided that a CT guided injection is the most suitable procedure for you. They believe that the potential benefits of the injection outweigh the potential risks. If you do not wish to have a CT guided injection please discuss your options with your doctor.

Please aim to arrive in the Scanning department 15 minutes before your CT appointment. While we endeavor to keep to your appointment time, we do occasionally have emergencies where a patient requires an urgent scan at short notice. If your appointment is delayed for any reason we will inform you of this and we would be very grateful for your patience and understanding.

Relatives and escorts

Please ensure that a relative or friend accompanies you to the scanning department. You are not permitted to drive after your procedure. Unfortunately, your relative or friend is not permitted to enter the examination room during your procedure.

Children

If you need to bring your children to the scanning department with you, please ensure there is another adult to accompany them whilst you have your procedure. Unfortunately, staff members are not permitted to look after your children during your procedure.

The Radiologist who carried out your CT guided injection will write a report and this will be sent to your referring doctor, usually in time for your next appointment.

The CT scanner is located within the RNOH Scanning department. This is situated at the top of the slope in the main hospital on the Stanmore site.  If driving we recommend you park in the Wood Lane carpark and the Scanning department is immediately on your right as you come into the hospital.

For advice, support or to raise a concern, contact our Patient Advice and Liaison Service (PALS). To make a complaint, contact the complaints department.

Telephone: 020 8909 5439 (PALS)
Email: rnoh.pals@nhs.net
Telephone: 020 8909 5717 / 5439 / 5741 (Complaints)
Email: rnoh.complaints@nhs.net

NHS 111

NHS 111 Offers medical help and advice from fully trained advisers supported by experienced nurses and paramedics. Available over the phone 24 hours a day.

Telephone: 111