Physiotherapy red flags: the urgent signs to know

A red flag is a finding that makes a common complaint look like something serious: low back pain with a bladder that will not empty, neck pain and headache that come from an artery rather than a joint, chest heaviness in an exercise class that does not settle with rest. The Canadian Physiotherapy Examination (CPTE) tests whether you recognize such signs and act on them, under a milestone of its own. This guide sets out the main red flags by region and by body system, in the words of the guidelines behind them: what each one signals, how urgent it is, and what the exam asks you to do.

The short answer

• A red flag raises suspicion; it does not make a diagnosis. The 2012 low back pain guideline defines red flags as findings that "increase the level of suspicion that there is a serious medical condition," and it reports a caution against relying on isolated ones.
• Some flags count for far more than others. In the same guideline, urine retention points strongly to cauda equina syndrome, and a history of cancer to a tumour.
• Each guideline sets its own urgency: 9-1-1 at once for signs of a stroke, even if they pass; immediate referral for cauda equina syndrome; referral within a few days for weakness that is getting worse.
• The CPTE tests the response as much as the recognition. Its milestone C.06 asks you to tell urgent from non-urgent and to facilitate "timely access to emergency or medical care."
• Learn the quiet presentations: a heart attack without chest pain, the hypoactive form of delirium, a child who only limps.

Our guide to CPTE practice questions includes a client-safety question on an urgent referral, and the QualExam lesson on urgent conditions teaches each condition below in full, with worked cases. A free account opens the Communication domain in full, so you can try the app before you pay.

What a red flag is

The 2012 clinical practice guideline on low back pain, from the Orthopaedic Section of the APTA, gives the definition: "Clinical findings that increase the level of suspicion that there is a serious medical condition presenting as common, nonserious, musculoskeletal conditions, are commonly described as red flags."

It makes screening a habit rather than an event. Clinicians "must be aware of the key signs and symptoms associated with serious medical conditions that cause low back pain and develop a system to continually screen for the presence of these conditions." When something turns up, its instruction is a single sentence: "When a potentially serious medical condition is suspected, clinicians should initiate referral to the appropriate medical practitioner."

Two cautions sit beside that. Serious causes are rare: in a primary care study the guideline reports, "the rate of serious pathology was quite low (0.9%), with most of the identified red flag cases, 8 of 11, being spinal fractures." And single flags mislead: most patients in that study had at least one, so its authors "cautioned against use of isolated red flags because of poor diagnostic accuracy."

Flags do not all weigh the same, though. The guideline's red flags table gives each finding a positive likelihood ratio; the higher the ratio, the more a positive finding raises the suspicion. Urine retention has a ratio of 18.0 for cauda equina syndrome. A history of cancer has 23.7 for a tumour, against 2.2 for an age over 50. Time can be a flag too: "failure of a patient to demonstrate improvement in a period of time no longer than 30 days can be interpreted as a red flag."

What the CPTE asks about red flags

Red flags belong to Client Safety and Client-Centred Care, one of the CPTE's seven Domains of Practice. The CPTE Blueprint 2025 gives that domain 15% of the whole exam, give or take 3 points, split at about 5% of the exam in the Written Section and 8% in the Oral Section. Its sixth milestone, C.06, reads: "Identify urgent health conditions that require immediate attention and take appropriate action."

The CPTE Blueprint 2025 Companion Guide spells out what that covers. The milestone "Assesses the ability to recognize clinical signs or symptoms that may indicate an acute or life-threatening condition, and respond promptly to ensure client safety. Content includes assessing the ability to differentiate between urgent and non-urgent conditions or changes in status and responding appropriately, including facilitating timely access to emergency or medical care as needed."

Read closely, that is three abilities: recognizing the sign, judging how urgent it is, and getting the client to the right care. A question can turn on any one of them. Its four options may all recognize the problem and differ only in how fast the client is sent on, and where.

CAPR's Model Standards of Practice add the preparation behind a prompt response. Under Risk Management and Safety, the physiotherapist "Verifies that there are policies and procedures in place related to risk and crisis management and is knowledgeable about these procedures," and "Participates in emergency preparedness and response training appropriate to the practice setting, method of service delivery, client population served, and identified safety risks." This guide is for exam study; at work, your setting's own emergency procedures are the ones to know.

Red flag screening: the questions to ask

Most red flags are found by asking. The national curriculum guidelines for Canada's physiotherapy programs, from CCPUP (2024), list focused questions to ask while gathering a client's information. Among them are "Clinical Flags", fever, chills and sweats, "Dizziness/lightheadedness", "Unexplained weight change", "Numbness/Paresthesia", weakness, "Mental health status/cognition changes", "Orthopnea, syncope", "Cough, sputum, hemoptysis", "Difficulty with swallowing", "Change in bowel function, incontinence" and "Urinary frequency, urgency, incontinence".

The 2012 low back pain guideline adds what to ask about the symptoms themselves: "the nature, onset, and progression of their symptoms", what makes them better or worse, "and any 24-hour pattern of symptom behavior." Constant pain that is worse at night is one of its flags for a tumour.

Mood belongs in the same screen. The WHO's mhGAP Intervention Guide (2016) says that anyone over 10 years of age with chronic pain, among others, "should be asked about thoughts or plans of self-harm in the last month, and about acts of self-harm in the last year." It explains why the question is safe: "Asking about self-harm does NOT provoke acts of self-harm." And if a client has a plan, the 2012 low back pain guideline is clear: "An immediate assessment by a medical and/or mental health professional is indicated for safety reasons if the patient had a plan to harm himself/herself or others."

A red flags list by region and system

The table gathers the main red flags a physiotherapist meets, each with the response its guideline gives. The sections after it add the detail and the sources.

Red flags for low back pain

The 2012 guideline's red flags table names five serious conditions that can present as back pain:

• A tumour: "Constant pain not affected by position or activity; worse with weight bearing, worse at night", with age over 50, a history of cancer, failure to improve within 30 days, unexplained weight loss, and no relief with bed rest.
• Cauda equina syndrome: urine retention, fecal incontinence, saddle anesthesia, and sensory or motor deficits in the feet.
• An infection: a recent infection, such as of the urinary tract or skin, intravenous drug use or a disorder that suppresses immunity, with "Deep constant pain, increases with weight bearing" and "Fever, malaise, and swelling".
• A compression fracture: a history of major trauma, "such as vehicular accident, fall from a height, or direct blow to the spine", age over 50, prolonged use of corticosteroids, point tenderness over the fracture, and more pain with weight bearing.
• An abdominal aneurysm: "Back, abdominal, or groin pain", peripheral vascular or coronary artery disease and its risk factors, a smoking history, a family history, age over 70, symptoms not related to movement, and an abnormal aortic pulse.

Of the five, cauda equina syndrome is the one the documents tie to immediate action. A 2007 review of sciatica in the BMJ grades the referrals: "Immediate referral is indicated in cases with a cauda equina syndrome. Acute severe paresis or progressive paresis are also reasons for referral (within a few days)." Without either, referral to a medical specialist is for clients whose symptoms "do not improve after conservative treatment for at least 6-8 weeks."

Cancer can also press on the spinal cord itself. A 2017 review of malignant spinal cord compression reports that "Pain is the most common initial symptom in patients with ESCC (89–90%) and may precede the development of other neurological symptoms by weeks to months." ESCC is epidural spinal cord compression. So in a client with a history of cancer, back pain may come weeks or months before any other neurological sign.

Red flags for neck pain

The 2017 revision of the neck pain clinical practice guideline makes screening part of every examination. Its recommendation, graded A, reads: "Clinicians should perform assessments and identify clinical findings in patients with neck pain to determine the potential for the presence of serious pathology (eg, infection, cancer, cardiac involvement, arterial insufficiency, upper cervical ligamentous insufficiency, unexplained cranial nerve dysfunction, or fracture), and refer for consultation as indicated."

The arteries need special care, because their problems can look like ordinary neck pain. IFOMPT's international cervical framework (2020) calls them "vascular masqueraders", with clients presenting with a vascular pathology of the neck "complaining of, for example, neck pain and headache." In the framework's tables, headache was reported in 81% of dissection events and neck pain in 57 to 80%. Unsteadiness or ataxia was the commonest sign of a vertebrobasilar artery dissection, at 67%, and a drooping eyelid (ptosis) of an internal carotid artery dissection, at 60 to 80%.

Spontaneous dissections are not tied to the usual risk factors, so the framework warns that "an absence of risk factors does not necessarily rule out the risk of serious neuro-vascular event." Its recommendation is plain: "It is recommended that physical therapists refer for immediate medical investigation when their clinical suspicion is supported by the reasoned patient history and physical examination findings suggest vascular pathology."

After trauma, the 2017 guideline uses the Canadian Cervical Spine Rule: people are at high risk if they "(1) are greater than 65 years of age, (2) have had a dangerous mechanism of injury, or (3) have paresthesias in the extremities," and "Those classified as high risk should undergo computed tomography (CT) or cervical radiography."

Stroke

Heart & Stroke's Canadian Stroke Best Practice Recommendations teach the signs with FAST: Face, "is it drooping?"; Arms, "can you raise both?"; Speech, "is it slurred or jumbled?"; Time, "to call 9-1-1 right away." The 2022 acute stroke recommendations ask the public and healthcare providers to respond "immediately when witnessing someone experiencing signs or symptoms of stroke by calling 9-1-1 or their local emergency number," "even if the signs or symptoms resolve." Their reason: "On average, two million neurons die with every minute that elapses following symptom onset."

The 2020 secondary prevention recommendations explain why the first two days matter. People seen within 48 hours of symptoms of a new stroke or transient ischemic attack "are at the highest risk for recurrent stroke and should be immediately sent to an emergency department." They also warn of a pattern that is easy to miss. Symptoms of vertebrobasilar ischemia, "diplopia, dysarthria, dysphagia, non-positional vertigo, ataxia," can fluctuate over more than 48 hours "and can be mistaken for stroke mimics; however, they also require urgent assessment."

Heart attack, and symptoms during exercise

Heart & Stroke's guide Living well with heart disease lists the common signs of a heart attack: chest discomfort ("Pressure, squeezing, fullness or pain, burning or heaviness"), discomfort in the "Neck, jaw, shoulder, arms, back", shortness of breath, sweating, nausea and light-headedness. Heart & Stroke's heart attack page adds that the picture can be mild: "Some people do not experience any chest pain," and "Some people only experience one symptom." The guide's first step is "CALL 9-1-1 or your local emergency number immediately or have someone call for you." In a clinic, the physiotherapist is that someone.

During exercise, the guide's rule has two steps: "If you are feeling not normal symptoms, stop the exercise," and "If the symptoms do not go away within a few minutes, Call 9-1-1 or your local emergency number." A heart attack is also not a cardiac arrest. Heart & Stroke's page puts it this way: "A heart attack needs immediate medical attention but doesn't need CPR. If a heart attack leads to a cardiac arrest, it is a critical medical emergency that requires immediate intervention – CPR and an AED."

Head injury and concussion

Parachute's Canadian Guideline on Concussion in Sport (2024) says that when a concussion is suspected, "the athlete should be removed from the activity immediately and undergo medical assessment as soon as possible." Some signs point to something worse: red flags that "potentially indicate a more severe head or spine injury, including loss of consciousness, convulsions, worsening headaches, repeated vomiting or neck pain." With those, "an ambulance should be called immediately to transfer the patient to the nearest emergency department," and "the athlete should not be left alone until the ambulance arrives."

Sepsis

The Sepsis-3 consensus (2016) defines sepsis as "life-threatening organ dysfunction caused by a dysregulated host response to infection." The WHO's fact sheet (2024) is blunt: "Sepsis is a medical emergency." Its common signs in adults include "fever or low temperature and shivering", "confusion", "difficulty breathing", "clammy and sweaty skin" and "high heart rate, weak pulse or low blood pressure".

Sepsis-3 also gave clinicians a quick bedside score, qSOFA: adults with suspected infection are more likely to do poorly "if they have at least 2 of the following clinical criteria": "respiratory rate of 22/min or greater, altered mentation, or systolic blood pressure of 100 mm Hg or less." It is not the preferred screening tool, though: the Surviving Sepsis Campaign's 2026 guidelines recommend other scores, such as NEWS, MEWS or SIRS, over qSOFA as the single tool to screen acutely ill patients in hospital. What the guidelines agree on is speed: "Sepsis and septic shock are medical emergencies; treatment and resuscitation should begin immediately."

Autonomic dysreflexia after spinal cord injury

For people with a spinal cord injury "at or above T6", the Can-SCIP guideline lists the signs of autonomic dysreflexia: an "Elevated systolic blood pressure greater than 20 mmHg above their usual baseline in adults", a "Sudden-onset headache", flushing or sweating. It warns that some people have "Few or no symptoms other than elevated blood pressure". The baseline matters because it is low: seated, such adults will likely have "low blood pressure (on average systolic blood pressure ~100 mmHg)."

Can-SCIP's first steps are to check blood pressure and, if it is raised, "immediately sit the individual up and lower the legs, if possible", loosen clothing, recheck every 1 to 2 minutes and look for the cause, starting with the urinary system. In its words, "Bladder and bowel problems are the most common causes of autonomic dysreflexia."

Low blood sugar

Diabetes Canada's guideline on hypoglycemia in adults (2023) sorts the symptoms into two groups. The adrenergic ones include trembling, palpitations, sweating, anxiety and hunger; the neuroglycopenic ones include "Difficulty concentrating", "Confusion, weakness, drowsiness, vision changes" and "Slurred speech, headache, dizziness". Its rule is that "It is important that hypoglycemia be treated as immediately and as safely as possible."

For levels 1 and 2, in which mental status is not significantly affected, that means 15 g of fast-acting carbohydrate, preferably glucose or sucrose as tablets or a solution, and a retest after 15 minutes. For a person who is unconscious, "Caregivers or support persons should call for emergency services." Exercise matters here: the sympathoadrenal response to hypoglycemia "is reduced during sleep, and following exercise or alcohol consumption."

Limbs: ischemia and compartment syndrome

The 2024 American guideline on peripheral artery disease defines acute limb ischemia as "Acute (≤2 wk) hypoperfusion of the limb that may be characterized by: pain, pallor, pulselessness, poikilothermia, paresthesias, and/or paralysis." It calls it "a medical emergency that must be recognized rapidly," because skeletal muscle tolerates ischemia for "about 4 to 6 hours."

Compartment syndrome is the other limb emergency. The British Orthopaedic Association's standard (updated July 2025) names its key findings: "pain out of proportion to the associated injury and pain on passive movement of the muscles of the involved compartments." When they appear, the person "should have circumferential dressings released to expose the skin and the limb elevated and re-evaluation within 30 minutes," and "Immediate surgical decompression should follow a diagnosis of compartment syndrome."

Children and older adults

Two groups show urgent conditions in quieter ways. For children, the Canadian Paediatric Society says that suspicion of a bone or joint infection "should be entertained when a patient presents acutely with pseudoparalysis (decreased movement or use) in an affected area or limping. Often pain is the only symptom." Fever "may not be a dominant feature at presentation," and a child with suspected septic arthritis "should be evaluated promptly by an orthopedic surgeon."

For older adults, a 2017 review in JAMA defines delirium as "an acute disorder of attention and cognition" and calls it "a common, serious, and often fatal condition among older patients." Its diagnosis rests on the person's usual state: "The cornerstone of diagnosis is determining the patient's baseline mental status, and the acuity of any changes; with delirium, the changes typically occur over hours to days." The quiet form is the one missed: "The hypoactive form is more common among older persons, often goes unrecognized, and is associated with higher rates of complications and mortality." And the review treats new delirium as urgent: "Because delirium can signify an acute medical emergency, all patients presenting with delirium need rapid, targeted evaluation for electrolyte or metabolic derangements, infection, or organ failure."

How urgent is urgent?

The word does not mean the same thing in every document. In the Canadian Cardiovascular Society's heart failure pocket guide (2021), an "urgent" referral is seen within 2 weeks, and only an "emergent" one within 24 hours. In the 2007 sciatica review, progressive weakness calls for referral "within a few days". In the stroke recommendations, there is no wait at all: 9-1-1.

Some red flags send the client to their own team rather than to an emergency department. Heart & Stroke's heart failure page asks people to weigh themselves daily and says: "If you gain or lose 2 kg (4 lb) or more in 2 days or 2.5 kg (5 lbs) or more in a week, contact your heart failure clinic or family doctor."

So learn each red flag with its time and its destination: an ambulance, an emergency department, a medical specialist, or the client's own physician or clinic. The Companion Guide's phrase, "emergency or medical care," names both kinds of destination, and choosing between them is part of the answer.

How the exam asks it

Every option here responds in some way; they differ in how fast and to whom. Knowing the flag gets you to the right condition, and knowing the guideline's response gets you to the key.

How to study red flags for the CPTE

• Learn each flag with three facts: what it suggests, how fast the client needs care, and where to send them.
• Learn the quiet presentations: a heart attack with no chest pain or with only one symptom, hypoactive delirium, autonomic dysreflexia with few symptoms beyond the blood pressure, a child's bone or joint infection without a prominent fever.
• Learn the scales: "urgent" in the heart failure pocket guide means 2 weeks, and "within a few days" in the sciatica review is not "immediate".
• Practise the response aloud for the Oral Section: what you found, why it is urgent, what you do now, and who you call. Our guide to CPTE oral practice shows how to score yourself.
• Practise with questions. In the course, question sets follow a client whose dizziness an emergency department called gastroenteritis, a faint during a game, and the checks before a cardiac exercise class.
• Then test and measure. Once serious pathology is ruled out, our guides to physiotherapy special tests and outcome measures cover the rest of the examination.
• Study the full lesson. The QualExam lesson on urgent conditions covers every condition here, with its sources, and more: asthma, anaphylaxis, COPD, seizures, meningitis and bleeding disorders among them. A free account opens Communication in full; our CPTE study plan shows where Client Safety fits in your weeks.