About a coccyx MRI scan
The coccyx, or tailbone, is the small triangular bone at the very bottom of the spine, below the sacrum. Pain in this area is called coccydynia. It is often worse when sitting, especially on hard surfaces, or when standing up from sitting. It is more common in women than in men.
The most common cause is an injury, such as a fall onto the bottom. Other causes include childbirth and prolonged sitting, and sometimes no clear cause is found. Most tailbone pain gets better within weeks to months. An MRI scan is usually considered if pain continues, to look for a cause and to rule out other problems.
MRI uses a strong magnetic field and radio waves, not X-rays, to show the coccyx, the joints between its segments, the surrounding soft tissues and the lower part of the spine. This is helpful because pain in the tailbone area can sometimes come from elsewhere, such as the lower back or nerve root cysts (Tarlov cysts) in the sacrum.
What happens during the scan
You lie on your back on the scanner bed, with a coil under your lower back and pelvis. If lying on your back is uncomfortable, let the radiographer know; cushions can help. The scanner is loud, so you will wear ear plugs or headphones, and you need to keep still while the pictures are taken. Contrast dye is not usually needed; where contrast is needed, it is charged separately.
What the scan can show
A coccyx MRI can help to look at:
- fractures and bruising of the coccyx after a fall
- inflammation and swelling around the coccyx and its joints
- changes in the position or alignment of the coccyx
- Tarlov cysts and other problems in the sacrum and lower spine that can cause pain in the same area
- infection, cysts and, rarely, tumours
When to get urgent help: contact your GP or NHS 111 if tailbone pain comes with a high temperature, or call 999 if you have numbness around your bottom or genitals or new problems controlling your bladder or bowel.
Preparing for your scan
No special preparation is needed for a coccyx MRI, and you can eat and drink normally. If sitting or lying is painful, you may want to take your usual painkillers before the appointment and bring a cushion for the journey.
You can usually eat, drink and take your normal medicines unless the scanning centre tells you otherwise. Wear loose, comfortable clothing without metal zips or buttons, and leave jewellery at home. You will be asked to remove metal items such as hair clips, hearing aids, coins and keys, and you may be asked to change into a gown.
Before the scan you will complete a safety questionnaire. Tell the team if you have a pacemaker, any metal implant, surgical clips or other device, if you have kidney problems or allergies, or if you are, or might be, pregnant or breastfeeding. If you feel anxious in enclosed spaces, let us know when you book. Some centres can offer a relaxant, and if you take one you will need someone to take you home and must not drive for 24 hours.
Frequently asked questions
What causes tailbone pain?
The most common cause is an injury, such as a fall onto the bottom. It can also follow childbirth or long periods of sitting, and sometimes there is no clear cause. Rarely, it is caused by infection or a growth.
Will an MRI show what is wrong with my coccyx?
An MRI can show fractures, inflammation, swelling and other problems around the coccyx, and can rule out other causes in the lower spine. Tailbone pain does not always show a clear cause on a scan, so your doctor will consider the results with your symptoms.
Will lying on my back for the scan be painful?
Tell the radiographer if it is uncomfortable. They can use cushions and pads to help you stay comfortable and still.
Do I need a referral?
You can tell us if you have a referral from your GP, physiotherapist or consultant and upload it when you book. If you do not have one, select “no referral” when you book and the scanning centre will confirm the next steps with you.
Sources
The information on this page has been gathered from various sources and is provided for general information only. It is not medical advice. TOP MRI is not liable for the accuracy or completeness of this information. Please speak to your doctor or the scanning centre about your own situation.