Some symptoms of cauda equina syndrome (CES) are known as red flags, because they mean you need emergency medical attention. Symptoms that are considered red flags include new problems with passing or controlling urine, changes to bowel control, numbness around the genitals or back passage, and severe or worsening neurological symptoms affecting both legs.

Cauda equina syndrome is a medical emergency. If you develop these warning signs, do not wait to see whether they improve. NHS guidance advises going to A&E or calling 999 where symptoms could indicate you have or are developing CES.

This guide explains the cauda equina red flags to recognise, what you should do if you notice them and what should happen when you seek help. We also explain what you can do if you previously reported red flag symptoms but they were not properly investigated or acted on.

For more information about the first signs of CES, including subtle or intermittent changes, read our guide to the early symptoms of cauda equina syndrome.

What do cauda equina red flags feel like?

Red flag symptoms are not always a complete loss of function. Sometimes the first concerning change is that something feels noticeably different from normal.

Bladder and urinary changes

Changes to bladder function are among the most important cauda equina red flags.

You may:

• Find it increasingly difficult to start passing urine
• Be unable to pass urine despite feeling that your bladder is full
• Develop urinary retention
• Lose the normal sensation of needing to pass urine, or the sensation of passing urine
• Have difficulty knowing whether your bladder is full or empty
• Lose control of urination

An inability to pass urine or a new loss of urinary control needs immediate medical attention. However, bladder dysfunction does not need to reach that point before it becomes a matter for a doctor to investigate.

The sacral nerve roots play an important role in controlling bladder function. Compression of these spinal nerves can interrupt the signals involved in urination.

Bowel changes

Cauda equina syndrome can also interfere with bowel sensation and bowel control.

You may stop feeling the normal urge to open your bowels, become unable to pass a stool, notice a loss of sensation when passing stool or become unable to control a bowel movement. Some people first notice altered sensation around the back passage when washing or wiping after going to the toilet. 

New bowel problems alongside back pain, sciatica, saddle numbness or urinary symptoms are important warning signs.

Saddle numbness and loss of sensation

Saddle anaesthesia means numbness, reduced sensation or altered sensation in the areas that would touch a saddle when sitting.

This can include the:

• Genitals
• Inner thighs
• Buttocks
• Area around the back passage (anus)

You do not need to have a complete loss of sensation. Tingling, shooting pains, numbness, reduced perineal sensation or simply noticing that the skin feels different can be significant.

For example, you may notice that you cannot feel toilet paper normally when wiping. Changes like this can indicate that the nerve roots responsible for sensation in the saddle area are being compressed.

Leg pain, weakness and bilateral sciatica

Back pain and sciatica are common and do not usually mean someone has cauda equina syndrome. The concern increases when neurological symptoms affect one or both legs, particularly where severe or worsening symptoms affect both sides.

Red flags include:

• Sciatica affecting both legs
• Severe leg pain with other CES symptoms
• New or worsening weakness in both lower limbs
• Numbness or a loss of sensation in both legs
• Difficulty walking because of worsening weakness

Severe back pain (particularly lower back pain) can occur with cauda equina syndrome, but pain alone does not establish a diagnosis. The important warning signs are the neurological changes that occur alongside it.

Changes to sexual function

Compression of the cauda equina nerves can also affect sexual function and genital sensation.

Possible red flags include a new loss of genital sensation, reduced sensation during sex, difficulty achieving an erection or changes in ejaculation or ability or orgasm.

Doctors should consider new sexual dysfunction alongside bladder and bowel symptoms, saddle anaesthesia, leg weakness and other symptoms of cauda equina syndrome.

When should you get emergency medical help?

If you develop cauda equina red flags, seek immediate medical attention. Do not wait for a routine GP appointment or wait at home to see whether the symptoms pass.

The NHS advises going to A&E or calling 999 where symptoms include any of the following: sciatica on both sides, severe or worsening weakness or numbness in both legs, numbness around the genitals or anus, difficulty starting to urinate, inability to urinate, loss of bladder control or loss of bowel sensation or control.

These symptoms do not necessarily mean that you have cauda equina syndrome. However, CES is a medical emergency, so doctors need to assess potentially serious warning signs promptly and rule out nerve compression.

What should happen when you go to hospital with cauda equina syndrome red flags?

If doctors suspect cauda equina syndrome, they should investigate urgently to establish whether the cauda equina nerve roots are compressed.

Your symptoms should be assessed

A doctor should ask when your symptoms began and whether they have changed or worsened.

A physical exam and neurological assessment may also be used to check power and sensation in the lower limbs and other relevant areas.

An emergency MRI scan may be needed

Magnetic resonance imaging (MRI) is the key imaging test used where cauda equina syndrome is suspected.

An MRI scan allows doctors to see whether the cauda equina nerve roots are being compressed within the spinal canal. It may also identify the cause of the compression, such as a large disc herniation or spinal stenosis.

The national suspected CES pathway states that emergency MRI should take place as soon as possible where cauda equina syndrome is suspected.

Read more in our guide to common cauda equina syndrome test methods.

Confirmed compression should be escalated urgently

If an MRI scan confirms cauda equina compression, the case should be referred immediately to the spinal surgeons.

The spinal team will review the MRI findings, symptoms and diagnosis and decide what treatment is required. Where decompression surgery is needed, cauda equina syndrome is treated as a time-sensitive emergency.

There is not one universal 24 or 48-hour rule that applies identically to every patient. The urgency of surgery depends on the person’s presentation and clinical findings, but treatment should not be unnecessarily delayed where the cauda equina nerve roots are compressed and the patient has concerning red flag symptoms.

Why is acting on cauda equina syndrome red flags quickly important?

The cauda equina contains multiple lumbar and sacral nerve roots that carry signals between the spine and the bladder, bowel, sexual organs and lower limbs.

If these nerves remain compressed, permanent damage can occur. The effects can include lasting urinary problems, bowel dysfunction, sexual dysfunction, numbness, pain, weakness and reduced mobility.

What if cauda equina syndrome red flags were missed?

Sometimes people seek medical attention because they recognise that something is wrong, but the significance of their symptoms is not properly recognised or investigated.

A delayed diagnosis does not automatically mean medical negligence occurred. However, there may be grounds to investigate a medical negligence claim where care fell below a reasonable standard and the delay caused or contributed to additional injury.

Red flags were not recognised

Examples can include:

• A GP failing to recognise new bladder, bowel, saddle-area or bilateral leg symptoms.
• A physiotherapist not arranging an urgent referral to hospital for medical assessment after red flags were reported.
• An emergency department doctor failing to investigate urinary retention, saddle anaesthesia, loss of sensation or severe neurological symptoms appropriately.
• Relevant symptoms not being recorded or escalated.

Diagnosis or treatment was delayed

Other cases may involve:

• An avoidable delay in arranging an MRI scan when cauda equina syndrome was or should have been suspected.
• MRI findings showing nerve compression not being acted on promptly.
• An avoidable delay in referral to the spinal surgeons.
• An avoidable delay in emergency surgery or other treatment. 

Whether medical negligence occurred depends on what symptoms were reported, what action should reasonably have been taken and whether earlier diagnosis or treatment would have changed the outcome.

How we help if cauda equina syndrome red flags were missed

If you are concerned that red flags of cauda equina syndrome were overlooked or that diagnosis or treatment was delayed, our medical negligence solicitors can investigate what happened.

We start by listening to your experience and establishing when your symptoms developed, what you told the doctors, nurses or physiotherapists involved in your care, and what happened next.

We gather your medical records and other relevant evidence to review appointments, emergency department attendances, neurological assessments, MRI scans, referrals and treatment. We will instruct independent medical experts to consider whether your care met a reasonable standard and whether any failings caused or contributed to your ongoing problems. 

Find out more about our cauda equina syndrome claims service.