Most Examined NICE Guidelines for Emergency Medicine: FRCEM and MRCEM Emergency Medicine Guide

NICE guidance drives a large proportion of UK Emergency Medicine exam questions because it turns common ED presentations into clear management decisions. In practice and in exams, marks are won by knowing the threshold that changes what you do next: who needs CT, who needs observation, who needs immediate antibiotics, who can be discharged, and who needs senior referral. The highest-yield topics are fever in under 5s, head injury, and cervical spine assessment, followed closely by sepsis, acute coronary syndromes, low back pain and sciatica red flags, and venous thromboembolism pathways. The aim is not to reproduce full guidelines, but to extract the parts most likely to affect ED decisions and exam performance.

Why This Topic Matters in the Emergency Department

Emergency clinicians use guideline-based thresholds every shift. Examiners know this, so NICE-based questions are common in MRCEM SBA, FRCEM SBA, and FRCEM OSCE.

• They test safe, standardised decision-making
• They reward precise knowledge of imaging and treatment triggers
• They often focus on borderline cases rather than obvious pathology
• They are highly relevant to discharge safety-netting and referral decisions

The most examined NICE-linked ED topics are:

Guideline area	Why it is examined	Typical exam focus
Fever in under 5s	Common paediatric ED presentation with risk stratification	Traffic light features, age thresholds, admission vs discharge
Head injury in adults	Time-critical imaging decisions	CT within 1 hour, CT within 8 hours, anticoagulation, discharge
Head injury in children	Different thresholds from adults	Immediate CT vs 4-hour observation
Cervical spine injury	Major trauma and safe clearance	Who needs imaging, who can be clinically cleared
Sepsis	Recognition and early treatment	High-risk features, lactate, antibiotics, escalation
Acute coronary syndromes	Core ED chest pain topic	ECG changes, troponin pathways, disposition
Low back pain and sciatica	Avoiding unnecessary imaging while spotting emergencies	Cauda equina, cancer, infection, fracture red flags
Venous thromboembolism	Structured risk assessment	Wells-based pathways, D-dimer use, imaging triggers

Key Definitions

• Immediate CT: imaging required urgently, usually within 1 hour of identifying the indication
• Delayed CT: imaging required within a longer defined timeframe, classically within 8 hours in selected adult head injury patients
• Observation period: monitored reassessment used when immediate imaging is not yet mandated but risk is not low enough for discharge
• Traffic light system: NICE paediatric fever risk stratification into green, amber, and red features
• Clinical clearance: deciding that imaging is not required after structured assessment and application of a validated rule or NICE-compatible criteria
• Safety-netting: clear discharge advice about what to watch for, what to do if symptoms worsen, and when to return

Essential Pathophysiology

The exam value of these guidelines comes from the underlying pathophysiology.

• Fever in under 5s: the concern is occult serious bacterial infection, meningitis, sepsis, pneumonia, UTI, and meningococcal disease
• Head injury: the key pathology is intracranial haemorrhage, cerebral oedema, skull fracture, and secondary brain injury from delayed recognition
• Cervical spine injury: unstable bony or ligamentous injury can lead to catastrophic neurological deterioration if missed
• Sepsis: dysregulated host response causes tissue hypoperfusion, organ dysfunction, and shock
• ACS: plaque rupture and coronary thrombosis can cause myocardial ischaemia or infarction even when initial observations are normal
• Low back pain red flags: the dangerous causes are cord or cauda equina compression, malignancy, infection, and fracture
• VTE: venous thrombosis and embolisation can cause sudden cardiorespiratory compromise or limb-threatening DVT

Clinical Presentation

These guidelines are usually tested through common ED presentations rather than by naming the guideline directly.

• Febrile infant or child with no clear source
• Adult or child after head injury with vomiting, amnesia, seizure, anticoagulation, or reduced GCS
• Trauma patient with neck pain or distracting injury
• Unwell patient with fever, tachycardia, hypotension, or altered mental state
• Chest pain with possible ACS
• Back pain with urinary symptoms, saddle anaesthesia, fever, or cancer history
• Dyspnoea, pleuritic chest pain, unilateral leg swelling, or suspected PE/DVT

Red Flags and High-Risk Features

These are the thresholds most likely to appear in exam stems.

Topic	High-risk feature	Why it matters
Fever under 5s	Age under 3 months with temperature 38°C or above	Red feature; urgent paediatric assessment
Fever under 5s	Age 3 to 6 months with temperature 39°C or above	Amber feature; lower threshold for investigation/admission
Fever under 5s	Non-blanching rash, reduced consciousness, grunting, CRT 3 seconds or more	Possible serious bacterial infection or meningococcal disease
Adult head injury	GCS 12 or less on initial assessment, or less than 15 at 2 hours	CT head within 1 hour
Adult head injury	Suspected open or depressed skull fracture, signs of base of skull fracture, focal neurology, post-traumatic seizure	CT head within 1 hour
Adult head injury	More than 1 episode of vomiting	CT head within 1 hour
Child head injury	GCS less than 14, or less than 15 if under 1 year	CT head within 1 hour
Child head injury	Suspected skull fracture, focal neurology, post-traumatic seizure	CT head within 1 hour
Child head injury	Loss of consciousness over 5 minutes, abnormal drowsiness, 3 or more vomits, dangerous mechanism, amnesia over 5 minutes, bleeding disorder	Observation or CT depending on combination of factors
C-spine injury	GCS under 15, paraesthesia, focal neurology, dangerous mechanism, inability to rotate neck 45 degrees	Imaging required
Sepsis	Hypotension, lactate elevation, altered mental state, mottling, oliguria	High-risk sepsis; urgent treatment and escalation
ACS	Ongoing chest pain, ischaemic ECG changes, haemodynamic instability	Immediate ACS pathway
Low back pain	Saddle anaesthesia, urinary retention, bilateral sciatica, progressive weakness	Possible cauda equina syndrome
VTE	Haemodynamic instability with suspected PE	High-risk PE; urgent senior management

Differential Diagnosis

Exams often reward recognising that a red flag does not equal a single diagnosis, but still mandates urgent action.

• Febrile child with non-blanching rash: meningococcal disease, viral illness, mechanical petechiae, ITP, HSP, haematological malignancy
• Head injury with vomiting: concussion, intracranial bleed, pain, migraine, intoxication
• Neck pain after trauma: muscular strain, cervical fracture, ligamentous injury, spinal cord injury
• Chest pain: ACS, PE, aortic syndrome, pneumothorax, pericarditis, musculoskeletal pain
• Back pain: mechanical pain, cauda equina, epidural abscess, vertebral fracture, metastatic disease, AAA
• Dyspnoea with pleuritic pain: PE, pneumonia, pneumothorax, ACS, heart failure

Initial ED Assessment

For all of these topics, the first step is structured ED assessment rather than immediate guideline recitation.

1. ABCDE assessment
2. Immediate treatment of life-threatening problems
3. Focused history including timing, mechanism, comorbidity, anticoagulants, immunosuppression, and social context
4. Targeted examination
5. Apply the relevant NICE or NICE-compatible decision threshold
6. Decide on imaging, observation, treatment, referral, or discharge

High-yield history points:

• Age, especially under 3 months, under 1 year, older age, frailty
• Anticoagulants and antiplatelets
• Mechanism of injury
• Vomiting count
• Loss of consciousness and amnesia duration
• Seizure after injury
• Fever duration and source
• Urinary symptoms in febrile children
• Cancer, IV drug use, steroid use, immunosuppression in back pain
• Pregnancy and postpartum state in VTE assessment

Investigations

1. Fever in under 5s

The key is age-stratified and risk-stratified investigation.

Group	Key NICE-aligned approach
Under 3 months with temperature 38°C or above	Red feature. Urgent paediatric assessment. Blood tests and urine testing are usually required. Blood culture is commonly indicated. Admission is usual. Empirical IV antibiotics depend on age, appearance, and local paediatric/neonatal sepsis pathway.
Age 3 to 6 months with temperature 39°C or above	Amber feature. Lower threshold for bloods, urine testing, observation, and admission depending on appearance and source.
Any age with unexplained fever	Consider urine testing for UTI.
Respiratory signs	Chest X-ray only if clinically indicated; not routine in every febrile child.
Suspected meningitis or encephalitis	Consider lumbar puncture after stabilisation and senior review; do not delay urgent treatment in the toxic child.

Traffic light features to know:

Domain	Amber features	Red features
Colour	Pallor reported by parent or carer	Pale, mottled, ashen, blue
Activity	No smile, decreased activity, wakes only with prolonged stimulation	No response to social cues, appears ill, does not wake or stay awake, weak/high-pitched/continuous cry
Respiratory	Nasal flaring, RR over 50 age 6 to 12 months, RR over 40 over 12 months, oxygen saturation 95% or less, crackles	Grunting, RR over 60, moderate or severe chest indrawing
Hydration	Dry mucous membranes, poor feeding, CRT 3 seconds or more, reduced urine output	Reduced skin turgor
Other	Fever 5 days or more, rigors, limb/joint swelling, non-weight-bearing limb	Age under 3 months and temp 38°C or above, non-blanching rash, bulging fontanelle, neck stiffness, status epilepticus, focal neurology, focal seizures, bile-stained vomiting

Important age thresholds:

• Tachycardia: over 160 under 12 months, over 150 age 12 to 24 months, over 140 age 2 to 5 years
• Tachypnoea: over 50 age 6 to 12 months, over 40 over 12 months
• Respiratory rate over 60 is a red feature
• CRT 3 seconds or more is an amber feature

Antipyretic exam points:

• Use paracetamol or ibuprofen if the child is distressed
• Do not use antipyretics solely to reduce temperature
• Do not give both routinely at the same time
• Do not use antipyretics to prevent febrile convulsions

2. Adult head injury

This is one of the highest-yield NICE topics in EM exams.

CT head within 1 hour if any of the following are present in an adult with head injury:

• GCS 12 or less on initial assessment in the ED
• GCS less than 15 at 2 hours after the injury
• Suspected open or depressed skull fracture
• Any sign of base of skull fracture
• Post-traumatic seizure
• Focal neurological deficit
• More than 1 episode of vomiting

Signs of base of skull fracture commonly tested:

• Haemotympanum
• Panda eyes
• CSF leak from ear or nose
• Battle’s sign

CT head within 8 hours of injury, or within 1 hour if the patient presents more than 8 hours after injury, if there has been some loss of consciousness or amnesia since the injury and any of the following are present:

• Age 65 or over
• Any current bleeding or clotting disorder, including anticoagulant use
• Dangerous mechanism of injury
• More than 30 minutes of retrograde amnesia before the injury

Dangerous mechanism in adults:

• Pedestrian or cyclist struck by motor vehicle
• Occupant ejected from motor vehicle
• Fall from more than 1 metre or more than 5 stairs

Anticoagulation and antiplatelets:

• Anticoagulation is a major exam discriminator and lowers the threshold for CT
• Do not dismiss a normal initial examination in an anticoagulated patient with head injury
• Antiplatelet therapy is relevant, especially if associated with other risk factors, but exam stems usually make anticoagulation the key trigger
• Always check local policy for DOAC, warfarin, and antiplatelet pathways

3. Paediatric head injury

Children are tested differently from adults. The key distinction is immediate CT versus structured observation.

CT head within 1 hour if any of the following are present:

• Suspicion of non-accidental injury
• Post-traumatic seizure without history of epilepsy
• GCS less than 14 on initial assessment, or less than 15 if under 1 year
• GCS less than 15 at 2 hours after injury
• Suspected open or depressed skull fracture, or tense fontanelle
• Any sign of base of skull fracture
• Focal neurological deficit
• For babies under 1 year, bruise, swelling, or laceration more than 5 cm on the head

Observe for at least 4 hours from the injury if any of the following are present and immediate CT is not already indicated:

• Loss of consciousness lasting more than 5 minutes
• Abnormal drowsiness
• 3 or more discrete episodes of vomiting
• Dangerous mechanism of injury
• Amnesia lasting more than 5 minutes
• Any current bleeding or clotting disorder

During observation, perform CT head within 1 hour if any of the following develop:

• GCS less than 15
• Further vomiting
• Further episode of abnormal drowsiness

Dangerous mechanism in children:

• High-speed road traffic collision as pedestrian, cyclist, or vehicle occupant
• Fall from more than 3 metres
• High-speed injury from projectile or object

Paediatric exam traps:

• Vomiting threshold differs from adults: 3 or more vomits in children, more than 1 episode in adults
• Observation for 4 hours is a classic SBA answer
• Non-accidental injury must always be considered

4. Cervical spine injury assessment

NICE-compatible trauma assessment is commonly examined through practical clearance decisions.

Suspect cervical spine injury in trauma patients with:

• Neck pain or midline tenderness
• Focal neurological deficit or paraesthesia
• Reduced GCS
• Dangerous mechanism
• Distracting injury

Imaging is required if high-risk features are present. In alert, stable patients, low-risk factors may allow assessment of active neck rotation. If the patient cannot actively rotate the neck 45 degrees left and right, imaging is required.

High-yield practical points:

• Do not clinically clear the cervical spine in an intoxicated, confused, or unreliable patient
• Persistent midline tenderness usually mandates imaging
• CT is the usual first-line imaging modality in adults with suspected cervical spine injury
• Children require age-appropriate trauma assessment and senior input

5. Sepsis

NICE sepsis guidance is often tested alongside practical ED sepsis care.

Think sepsis when infection is suspected and there are signs of physiological derangement or organ dysfunction.

High-risk features include:

• Hypotension
• Altered mental state
• Mottled or ashen skin
• Raised lactate
• Reduced urine output
• Hypoxia
• Non-blanching rash

Investigations commonly required:

• Blood gas including lactate
• FBC, U&E, CRP
• Blood cultures if this does not delay antibiotics
• Urinalysis and urine culture if indicated
• Imaging directed by source

6. Acute coronary syndromes

NICE chest pain and ACS questions usually test recognition of high-risk features and appropriate disposition.

Investigations:

• Immediate ECG
• Serial troponin according to local validated pathway
• Chest X-ray only if clinically indicated

High-risk features:

• Ongoing or recurrent chest pain
• Ischaemic ECG changes
• Haemodynamic instability
• Arrhythmia
• Heart failure features

7. Low back pain and sciatica

NICE is frequently examined here because the correct answer is often not to image uncomplicated back pain.

Red flags requiring urgent imaging or specialist discussion include:

• Urinary retention or incontinence
• Saddle anaesthesia
• Bilateral sciatica
• Progressive motor weakness
• Fever or immunosuppression suggesting spinal infection
• History of malignancy or unexplained weight loss
• Major trauma or suspected fracture

8. Venous thromboembolism

NICE-based VTE pathways are structured and exam-friendly.

For suspected DVT:

• Use a two-level DVT Wells score
• If likely, arrange proximal leg ultrasound and interim anticoagulation if imaging is delayed and bleeding risk is acceptable
• If unlikely, use D-dimer to guide need for imaging

For suspected PE:

• Use a two-level PE Wells score
• If likely, arrange CTPA or V/Q scanning as appropriate
• If imaging is delayed and PE is likely, consider interim anticoagulation if safe
• D-dimer is useful in low-risk or unlikely PE, not as a blanket test for everyone

Management in the Emergency Department

Immediate management priorities

1. Resuscitate first if unstable
2. Apply the relevant guideline threshold early
3. Do not delay time-critical treatment for diagnostic completeness
4. Escalate early when red features are present

Fever in under 5s

• ABCDE assessment
• Urgent senior paediatric review for red features
• Give oxygen if hypoxic
• Gain IV or IO access if seriously unwell
• Take cultures and bloods if indicated, but do not delay treatment in suspected sepsis or meningococcal disease
• Give empirical IV antibiotics according to local paediatric or neonatal guidance when serious bacterial infection or sepsis is suspected
• If shocked, give isotonic crystalloid bolus with reassessment after each bolus and early escalation
• Consider PICU involvement in severe disease

Practical exam points:

• Under 3 months with temperature 38°C or above should not be treated as a simple viral illness without senior review
• Urine testing is important in unexplained fever
• Fever for 5 days or more should prompt search for source and consideration of inflammatory conditions such as Kawasaki disease

Adult and paediatric head injury

• ABCDE and C-spine protection where appropriate
• Apply CT criteria precisely
• Observe when indicated rather than scanning everyone
• Escalate to neurosurgery if CT shows significant intracranial pathology or clinical deterioration occurs
• Review anticoagulation and reversal needs according to local major haemorrhage or neurosurgical pathways

Neurosurgical discussion is usually required for:

• Intracranial haemorrhage
• Depressed skull fracture
• Deteriorating GCS
• Persistent focal neurology
• Penetrating injury

Sepsis

• Recognise early
• Take cultures if this does not delay treatment
• Give broad-spectrum antibiotics promptly when indicated
• Measure lactate
• Give IV fluids if hypoperfused, with reassessment
• Escalate to critical care early if shock or organ dysfunction is present

ACS

• Immediate ECG
• Antiplatelet and antithrombotic treatment according to ACS type and local pathway
• Urgent cardiology involvement for STEMI or high-risk NSTEMI
• Use validated troponin pathways for low-risk chest pain

Low back pain and sciatica

• Avoid routine imaging in uncomplicated mechanical back pain
• Urgently investigate red flags
• Discuss suspected cauda equina, spinal infection, or cord compression early with spinal or neurosurgical services

VTE

• Use structured pre-test probability
• Do not rely on D-dimer in high-probability patients
• Arrange definitive imaging promptly
• Consider interim anticoagulation if imaging is delayed and bleeding risk is acceptable

Disposition, Referral and Follow-Up

Fever in under 5s

Discharge may be appropriate if:

• No red features
• Child is clinically well after assessment or observation
• Feeding and hydration are satisfactory
• Observations are acceptable
• Carers understand safety-netting and can return promptly

Admit or seek paediatric review if:

• Any red feature
• Young infant with fever, especially under 3 months
• Persistent amber features
• Uncertain source with ongoing concern
• Unsafe social circumstances or poor access to review

Head injury

Discharge may be appropriate if:

• CT not indicated or CT normal
• GCS 15 and back to baseline
• No concerning deterioration during observation
• A responsible adult is available where required
• Written and verbal head injury advice is given

Admit, observe, or refer if:

• Abnormal CT
• Persistent symptoms or reduced GCS
• Seizure, anticoagulation concerns, or social concerns
• Safeguarding concerns in children

Sepsis

• High-risk sepsis usually requires admission
• Critical care referral if shock, rising lactate, or organ dysfunction

ACS

• STEMI and high-risk NSTEMI require admission
• Low-risk chest pain may be discharged only through a validated pathway with clear follow-up and safety-netting

Low back pain

• Simple mechanical pain can usually be discharged with analgesia and advice
• Red flag pathology requires urgent imaging, referral, or admission

VTE

• Stable DVT and selected low-risk PE may be managed ambulatory under local pathways
• Unstable PE requires admission and senior escalation

Special Groups

Paediatrics

• Age thresholds matter greatly in fever and head injury
• Observation is often safer than immediate discharge in borderline cases
• Always consider safeguarding and non-accidental injury

Older adults

• Lower threshold for CT head after injury
• Frailty and anticoagulation increase risk
• Delirium may be the presenting feature of sepsis or ACS

Pregnancy

• VTE risk is increased in pregnancy and postpartum
• Use pregnancy-appropriate imaging and specialist discussion where needed
• Do not dismiss serious pathology because of pregnancy-related symptom overlap

Immunosuppressed patients

• Lower threshold for sepsis work-up and admission
• Back pain with fever or immunosuppression raises concern for spinal infection

Anticoagulated patients

• Head injury thresholds are lower
• Bleeding risk affects VTE and trauma decisions
• Always check the specific drug and timing of last dose

Common Pitfalls

• Calling age 3 to 6 months with temperature 39°C or above a red feature. It is an amber feature.
• Missing that age under 3 months with temperature 38°C or above is a red feature.
• Over-investigating every green-group febrile child.
• Under-investigating unexplained fever without urine testing.
• Using antipyretics to treat the number rather than the child’s distress.
• Forgetting that adults need CT for more than 1 vomiting episode after head injury.
• Forgetting that children are often observed for 4 hours rather than scanned immediately.
• Ignoring anticoagulation in head injury.
• Trying to clinically clear the cervical spine in an unreliable patient.
• Ordering MRI or X-ray routinely for uncomplicated low back pain.
• Using D-dimer in a patient with high pre-test probability of PE instead of arranging imaging.

FRCEM and MRCEM Exam Tips

• MRCEM usually tests the rule itself. Learn exact thresholds.
• FRCEM usually tests application when the case is imperfect: anticoagulation, age extremes, social concerns, mixed features.
• If a question gives one key threshold, it is usually there to trigger the next step.
• In trauma SBAs, count vomiting episodes, note GCS timing, and look for mechanism details.
• In paediatric fever questions, classify the child first into green, amber, or red before choosing investigations or disposition.
• In OSCEs, always include safety-netting and senior escalation where appropriate.
• When two answers seem plausible, choose the safer guideline-based option.

Top thresholds to memorise:

• Under 3 months and temperature 38°C or above = red feature
• Age 3 to 6 months and temperature 39°C or above = amber feature
• CRT 3 seconds or more = amber feature
• Respiratory rate over 60 in febrile child = red feature
• Adult head injury: more than 1 vomit = CT within 1 hour
• Child head injury: 3 or more vomits = observe at least 4 hours or CT depending on associated features
• Adult dangerous mechanism: fall over 1 metre or over 5 stairs
• Child dangerous mechanism: fall over 3 metres
• Adult age 65 or over with LOC or amnesia plus risk factor = CT within 8 hours
• Unable to rotate neck 45 degrees left and right in a suitable trauma patient = image the cervical spine

How This Appears in SBA Questions

Typical question stems:

• “A 2-month-old infant has a temperature of 38.2°C but looks well. What is the most appropriate next step?”
• “A 72-year-old on apixaban falls, has brief amnesia, and is now GCS 15. What is the next investigation?”
• “A 6-year-old vomits three times after a head injury but has no focal neurology. What is the most appropriate management?”
• “A trauma patient has neck pain but is alert and stable. Which feature mandates cervical spine imaging?”
• “A patient with back pain has urinary retention and saddle anaesthesia. What is the next step?”
• “A patient with pleuritic chest pain and high PE Wells score has delayed imaging. What should happen next?”

Key discriminator clues:

• Exact age band
• Temperature threshold
• Number of vomiting episodes
• GCS at presentation and at 2 hours
• Loss of consciousness or amnesia
• Anticoagulant use
• Dangerous mechanism wording
• Ability to rotate neck
• Presence of red flag neurology or sepsis physiology

Common wrong answer traps:

• Discharging a febrile infant under 3 months without senior review
• Choosing skull X-ray instead of CT in head injury
• Scanning every child with minor head injury instead of observing for 4 hours
• Using D-dimer in a clearly high-risk PE patient
• Requesting routine lumbar spine imaging for simple sciatica without red flags
• Giving antipyretics solely to reduce fever or prevent febrile convulsions

Key Takeaways

• For exams, the highest-yield NICE topics are fever in under 5s, adult and paediatric head injury, and cervical spine assessment.
• Age under 3 months with temperature 38°C or above is a red feature in febrile children.
• Age 3 to 6 months with temperature 39°C or above is an amber feature, not red.
• Urine testing is important in unexplained fever in children.
• Adult head injury CT within 1 hour is triggered by reduced GCS, skull fracture signs, seizure, focal neurology, or more than 1 vomit.
• Adult CT within 8 hours applies when there has been loss of consciousness or amnesia plus age 65 or over, anticoagulation or clotting disorder, dangerous mechanism, or retrograde amnesia over 30 minutes.
• Children with head injury often need 4-hour observation rather than immediate CT.
• Anticoagulation is a major head injury exam discriminator.
• Cervical spine imaging is required when high-risk features are present or the patient cannot safely be clinically cleared.
• In sepsis, urgent treatment should not be delayed for complete investigation.
• In low back pain, the key exam skill is spotting red flags while avoiding unnecessary imaging.
• In VTE, use structured pre-test probability and do not misuse D-dimer.

Further Reading

• NICE Guideline NG143: Fever in under 5s: assessment and initial management
• NICE Guideline NG232: Head injury: assessment and early management
• NICE Guideline NG41: Spinal injury: assessment and initial management
• NICE Guideline NG51: Sepsis: recognition, diagnosis and early management
• NICE Guideline NG185: Acute coronary syndromes
• NICE Guideline NG59: Low back pain and sciatica in over 16s
• NICE Guideline NG158: Venous thromboembolic diseases
• RCEM guidance and learning resources on head injury, sepsis, and trauma imaging
• Resuscitation Council UK and APLS-aligned paediatric emergency care resources
• BTS and SIGN guidance where relevant to chest pain, respiratory infection, and VTE pathways