Back Pain Red Flags: When Back Pain Needs Urgent Attention

What are back pain red flags?

Red flags are features in your history or symptoms that raise the chance of a serious cause behind back pain, such as nerve compression, a fracture, an infection or cancer. These causes are uncommon. Most back pain, even severe back pain, is not dangerous. Red flags help doctors and patients spot the small number of cases that need fast action.

No single red flag proves something serious is going on. Doctors look at the overall picture, and some flags matter much more than others.

The emergencies: cauda equina syndrome

The nerves at the base of the spine (the cauda equina) control the bladder, bowel and sensation around the groin. If they’re squeezed, usually by a large disc bulge, they can be permanently damaged within hours to days. Go to an emergency department straight away if you have back pain or sciatica with:

• numbness or tingling around the groin, buttocks, genitals or inner thighs (“saddle” numbness)
• new difficulty passing urine, or not being able to feel when your bladder is full
• new loss of control of your bladder or bowel
• sciatica in both legs, or leg weakness that’s getting worse
• new problems with sexual function alongside these symptoms

Signs that need prompt assessment

These don’t usually need an ambulance, but they do need a doctor soon, often the same day:

• Possible fracture: back pain after a significant fall or accident, or sudden back pain in someone older or with thin bones (osteoporosis), including people who have taken medicines long term that can weaken bones.
• Possible infection: back pain with a fever or chills, after recent surgery or a serious infection, or in people with a weakened immune system or who inject drugs.
• Possible cancer: a past history of cancer is the most important flag. Unexplained weight loss and constant pain that doesn’t ease with rest or position also count.
• Nerve problems: weakness in a leg or foot, a foot that slaps or drags, or numbness that is spreading.

How reliable are red flags?

Less reliable than people assume. A systematic review in the BMJ found that most single red flags are poor at picking out cancer or fractures, and that many people without serious disease have at least one flag. A history of cancer was among the more useful features for spotting spinal cancer, and older age, significant trauma and prolonged use of bone-thinning medicines were more useful for fractures.

That’s why an international framework for red flags, published in 2020, recommends that clinicians weigh red flags together with the rest of the history and examination, rather than reacting to any one of them in isolation.

What doctors do when there’s a red flag

Depending on what’s suspected, your doctor may:

• send you straight to an emergency department (for suspected cauda equina syndrome)
• arrange an urgent scan, such as an MRI
• order blood tests to look for infection or inflammation
• arrange follow-up to check that symptoms are settling as expected

If there are no red flags, guidelines advise against routine scans. See our guide to lower back pain for what helps.

Can red flags be checked by telehealth?

A GP can go through red flags in detail by phone or video, because most of them come from your history. If a red flag needs a physical examination, a scan or emergency care, your GP will tell you where to go and how quickly.

References

1. Finucane LM, Downie A, Mercer C, et al. International Framework for Red Flags for Potential Serious Spinal Pathologies. J Orthop Sports Phys Ther. 2020;50(7):350-372.
2. Downie A, Williams CM, Henschke N, et al. Red flags to screen for malignancy and fracture in patients with low back pain: systematic review. BMJ. 2013;347:f7095.
3. Maher C, Underwood M, Buchbinder R. Non-specific low back pain. Lancet. 2017;389(10070):736-747.
4. Hartvigsen J, Hancock MJ, Kongsted A, et al. What low back pain is and why we need to pay attention. Lancet. 2018;391(10137):2356-2367.
5. healthdirect. Back pain.