A lumbosacral spine X-ray, or lumbar spine X-ray, is an imaging test that helps your doctor view the anatomy of your lower back.
The lumbar spine is made up of five vertebral bones. The sacrum is the bony “shield” at the back of your pelvis. It’s located below the lumbar spine. The coccyx, or tailbone, is located below the sacrum. The thoracic spine sits on top of the lumbar spine. The lumbar spine also has:
- large blood vessels
An X-ray uses small amounts of radiation to view your body’s bones. When focusing on the lower spine, an X-ray can help detect abnormalities, injuries, or diseases of the bones in that specific area. According to the Mayo Clinic, a lumbar spine X-ray can show whether you have arthritis or broken bones in your back, but it can’t show other problems with your muscles, nerves, or disks.
Your doctor could order a lumbar spine X-ray for a variety of reasons. It can be used to view an injury from a fall or accident. It can also be used to monitor the progression of a disease like osteoporosis or to determine if a treatment you’re having is working.
An X-ray is a useful test for many conditions. It can help your doctor understand the cause of chronic back pain or view the effects of injuries, disease, or infection. Your doctor may order a lumbar spine X-ray to diagnose:
- birth defects that affect the spine
- injury or fractures to the lower spine
- low back pain that's severe or lasts for more than four to eight weeks
- osteoarthritis, which is arthritis affecting the joints
- osteoporosis, which is a condition that causes your bones to thin
- abnormal curvature or degenerative changes in your lumbar spine, such as bone spurs
Your doctor might also use other imaging tests along with an X-ray to determine the cause of your back pain. These can include:
Each of these scans yields a different type of image.
All X-rays involve exposure to a small amount of radiation. This is typically harmless, but it’s an important issue if you’re pregnant or could be pregnant. The amount of radiation used is considered safe for adults but not for a developing fetus. Be sure to tell your doctor if you’re pregnant or believe you may be pregnant.
X-rays are routine procedures that don’t require much preparation.
Before the X-ray, you’ll be asked to remove any jewelry and other metallic items from your body. Tell your doctor if you have any metal implants from prior surgeries. Most likely, you’ll change into a hospital gown to prevent any buttons or zippers on your clothes from affecting the quality of the X-ray images.
X-rays are performed in a hospital’s radiology department or at a clinic that specializes in diagnostic procedures.
Usually, you will start by lying down on a table, facing up. A technician will move a large camera connected to a steel arm over your lower back. A film inside the table below you will capture the X-ray images of your spine as the camera moves overhead.
The technician may ask you to lie in several positions during the test, including on your back, side, stomach, or even standing depending on what views your doctor has requested.
While the images are taken, you’ll have to hold your breath and remain still. This ensures that the images are as clear as possible.
After the test, you can change back into your regular clothes and go about your day right away.
Your radiologist and doctor will review the X-rays and discuss their findings. Results from your X-ray may be available the same day.
Your doctor will determine how to proceed depending on what the X-rays show. They may order additional imaging scans, blood tests, or other tests to help make an accurate diagnosis.