WHEN BACK PAIN IS AN EMERGENCY
Almost everything on this site can wait two weeks. This page cannot.
The overwhelming majority of back pain is not dangerous, and being told so is usually correct. A small number of presentations are different, and in those the thing at risk is not comfort but function that does not come back. This page exists so you can tell them apart.
The findings that cannot wait
GO TO AN EMERGENCY DEPARTMENT NOW
Any of the following, together with back pain, is a same-hour problem. Do not wait for an appointment, and do not wait to see whether it settles overnight.
- New difficulty passing urine, or loss of bladder or bowel control. Retention comes before incontinence and is easy to dismiss as something else.
- Numbness in the saddle area — the inner thighs, the buttocks, the genitals, or a changed sensation when you wipe.
- Weakness in both legs, or weakness in one leg that is getting worse over hours or days.
- Severe back pain after a significant fall or a road collision, particularly if you have osteoporosis or are on long-term steroids.
- Back pain with fever, rigors, or a recent bloodstream infection, or back pain in someone who injects drugs.
Together, the first three describe cauda equina syndrome: compression of the nerve bundle below the end of the spinal cord. It is uncommon, it is a surgical emergency, and the window in which decompression preserves bladder and sexual function is measured in hours to a day or two, not weeks. Presenting late is the single most consequential delay in this entire specialty.
Be seen this week, not in a month
URGENT BUT NOT AN EMERGENCY
- A foot drop, or new weakness in one leg that is stable rather than worsening.
- Unexplained weight loss with back pain, or a history of cancer of any kind.
- Night pain that wakes you and is not relieved by changing position — distinct from the ordinary discomfort of rolling over.
- Back pain starting before age twenty or after age fifty-five for the first time.
- Progressive stiffness with prolonged morning symptoms in a younger adult, which points toward inflammatory disease rather than mechanical pain.
- Long-term steroid use, significant osteoporosis, or immunosuppression with new back pain.
These do not need an emergency department, and they do need an assessment with a low threshold for imaging — which is one of the few situations where a scan genuinely earns its place early.
Why this page is short and specific
Red-flag lists have a way of expanding until they cover most of human experience, at which point they stop being useful and start being frightening. The list above is deliberately narrow. If none of it applies to you, the odds are strongly that your back pain is mechanical, unpleasant and not dangerous — and that the right next question is which structure is generating it rather than whether something sinister is happening.
We would rather you over-read this page than under-read it, and we would also rather you not carry it around as background dread. Those two things are compatible: read it once, know what would change your plan, and then get on with the workup.
What we will not do
We will not invent a risk to make a point. Everything above is on this page because it changes what should happen next, and nothing is here to create urgency around a service. Where a finding points to an emergency department or to a surgeon, you will be told that on the day, plainly, rather than after a course of something.
If you are not sure
Call and describe it. The specific things worth saying out loud, because they are the ones people leave out:
- Whether anything has changed about passing urine — including simply going less often, or having to strain.
- Whether the numbness is anywhere you would sit on.
- Whether the weakness is getting worse, staying the same, or improving. The direction matters more than the amount.
- Whether you have had cancer, at any point, of any kind.
- Whether you have had a fever.
You can reach us at (314) 886-5904 or text (314) 886-5902. If it is one of the emergency findings, do not call us first. Go.
Common questions
What are the five red flags of back pain?
The short list most clinicians work from is: bladder or bowel change, saddle numbness, progressive leg weakness, significant trauma, and infection or cancer features such as fever, unexplained weight loss or a cancer history. The first three together are cauda equina syndrome and are the true emergency.
That is the subject of Numbness is information about a level. Where it sits tells us which nerve..
How quickly does cauda equina need treating?
Urgently, in hours. Delay is associated with permanent loss of bladder, bowel and sexual function, and that is the reason this is the one presentation where the advice is to bypass every normal pathway.
The detail is in If your toe is catching on stairs, that is weakness, and weakness is on a clock..
I have had back pain for years. Should I worry about this?
Long-standing mechanical back pain is not what this page is about. What matters is a change — a new neurological symptom, a new pattern, a new severity that is unlike your usual. Chronicity is reassuring; change is not. Three departures from your usual pattern are worth acting on rather than waiting out.
Is severe pain itself a red flag?
Not on its own. Severity correlates poorly with danger, and some of the most severe pain in this field comes from conditions that resolve completely. The red flags are about neurological function and systemic illness, not about intensity.
Numbness is information about a level. Where it sits tells us which nerve. goes through it in detail.
Related reading
- Lumbar radiculopathy
- Sciatica, and what impersonates it
- Spinal stenosis
- Before you agree to the operation
- Back pain doctor in St. Louis
Three departures from your usual pattern are worth acting on rather than waiting out.
If none of this applies, the question becomes which structure is generating your pain
That is a question with a method behind it, and it is what the rest of this practice does. Tell us how long it has been and what you have already been through.
12174 Natural Bridge Rd, Suite 301
St. Louis, MO 63044
At DePaul Hospital on Natural Bridge Road, inside the I-270 and I-70 interchange, on the west side of the airport.
Sources
- Finucane LM et al. International Framework for Red Flags for Potential Serious Spinal Pathologies. The Journal of orthopaedic and sports physical therapy, 2020. PubMed 32438853
- Han CS et al. Red flags to screen for vertebral fracture in people presenting with low back pain. The Cochrane database of systematic reviews, 2023. PubMed 37615643
- Galliker G et al. Low Back Pain in the Emergency Department: Prevalence of Serious Spinal Pathologies and Diagnostic Accuracy of Red Flags. The American journal of medicine, 2020. PubMed 31278933
- Expert Panel on Neurological Imaging et al. ACR Appropriateness Criteria® Low Back Pain: 2021 Update. Journal of the American College of Radiology : JACR, 2021. PubMed 34794594