Requires clinical gestalt for alternative diagnosis
MRI
MRI
Indications
Osteomyelitis concern
Deep soft tissue infection extent
Contraindications
Non compatible implanted devices
Severe claustrophobia without support
Protocol notes
Contrast enhancement when infection mapping needed
Non contrast sequences for compartment and muscle edema
Pitfalls
Early infection may be subtle
Motion artifact limits detail
CT
CT
Indications
Pelvic or iliac venous obstruction concern
Necrotizing infection gas concern
Contrast considerations
Renal dysfunction
Prior contrast reaction
Protocol notes
CT venography when proximal obstruction suspected
CT angiography when acute limb ischemia suspected
Pitfalls
Radiation exposure
Limited sensitivity for early cellulitis extent
Ultrasound
Ultrasound
Venous duplex compression ultrasound
First line imaging for suspected deep vein thrombosis
Proximal vs distal clot distinction
Point of care ultrasound adjuncts
Two point compression approach
Soft tissue cobblestoning for cellulitis
Baker cyst evaluation
Popliteal fossa fluid collection
Rupture tracking into calf
Pitfalls
Limited assessment of iliac veins
Reduced sensitivity for isolated distal deep vein thrombosis
Special Tests
Bedside measurements and maneuvers
Bedside measurements and maneuvers
Calf circumference comparison
Same landmark on both legs
Serial reassessment for progression
Skin marking for cellulitis spread
Border marking
Time stamp for progression
Passive stretch pain assessment
Foot dorsiflexion stretch
Toe extension stretch
Procedural diagnostics
Procedural diagnostics
Arthrocentesis when septic arthritis concern
Synovial fluid cell count
Gram stain and culture
Compartment pressure measurement when uncertain
Clinical concern persists despite equivocal exam
Surgical consultation aligned with measurement
ECG
Indications and high risk patterns
Indications and high risk patterns
ECG indications
Pulmonary embolism concern
Unexplained tachycardia
Concerning patterns for pulmonary embolism
Sinus tachycardia
Right heart strain patterns
Serial ECG logic
Worsening symptoms
New hypoxia
Assessment
Problem representation and severity
Problem representation and severity
Unilateral leg swelling with pain
Risk stratification for venous thromboembolism
Alternative diagnosis probability
Unilateral leg swelling without pain
Lymphedema vs venous obstruction
Chronicity assessment
Systemic features present
Infection severity assessment
Pulmonary embolism concern assessment
Working diagnoses
Working diagnoses
Suspected deep vein thrombosis (I82.4)
Pretest probability category
Ultrasound result status
Suspected cellulitis (L03.11)
Non purulent vs purulent features
Abscess excluded status
Suspected superficial thrombophlebitis (I80.0)
Proximity to deep system concern
Extent mapping
Suspected compartment syndrome (T79.A)
Time sensitive surgical risk
Neurovascular status trend
Plan
First 5 minutes and safety
First 5 minutes and safety
Monitoring and access
Cardiac monitor when pulmonary embolism concern
Pulse oximetry when dyspnea or chest symptoms
IV access when unstable or high risk
Immediate escalation
If hypotension or hypoxia, pulmonary embolism pathway
If cold pulseless limb, vascular surgery emergent
If compartment syndrome concern, orthopedic surgery emergent
Analgesia
Acetaminophen PO 1000 mg
Ibuprofen PO 400 mg
Avoid NSAIDs if high bleeding risk
Diagnostic sequencing
Diagnostic sequencing
Deep vein thrombosis pathway
Wells score category
D dimer when low or intermediate probability
Venous duplex ultrasound
Cellulitis pathway
Soft tissue ultrasound when abscess concern
CBC and inflammatory markers when systemic features
Limb threat pathway
Immediate vascular imaging consideration
Early surgical consultation
Therapeutics
Therapeutics
Anticoagulation for confirmed deep vein thrombosis
Apixaban PO 10 mg twice daily for 7 days
Apixaban PO 5 mg twice daily after day 7
Rivaroxaban PO 15 mg twice daily for 21 days
Rivaroxaban PO 20 mg once daily after day 21
Low molecular weight heparin when pregnancy
Avoid anticoagulation if active major bleeding
Cellulitis antibiotics local protocol dependent
Cephalexin PO 500 mg four times daily
If MRSA risk, doxycycline PO 100 mg twice daily
If severe systemic features, IV antibiotics pathway
Superficial thrombophlebitis symptom control
Compression and elevation
NSAID use if low bleeding risk
Anticoagulation consideration when extensive or near deep system
Hematoma management
Anticoagulant reversal decision based on severity
Compartment syndrome monitoring
Reassessment loop
Reassessment loop
Recheck timing
Every 30 to 60 minutes when severe pain
After analgesia effect window
Recheck targets
Pain trajectory
Neurovascular status
Swelling progression
Triggered escalation
Worsening pain out of proportion
New sensory deficit
New hypoxia or dyspnea
Disposition
Admission and higher level care
Admission and higher level care
ICU criteria
Hemodynamic instability
High risk pulmonary embolism features
Inpatient criteria for cellulitis
Rapid progression
Systemic toxicity
Immunocompromise
Inpatient criteria for deep vein thrombosis
Extensive iliofemoral clot
Phlegmasia concern
High bleeding risk requiring monitoring
Surgical admission criteria
Compartment syndrome concern
Necrotizing infection concern
Observation and discharge
Observation and discharge
Observation pathway
Pending ultrasound with moderate risk features
Early cellulitis with borderline systemic signs
Discharge criteria
Stable vital signs
No limb threat features
Reliable follow up
Follow up timing
Within 24 to 72 hours for cellulitis reassessment
Within 7 days for anticoagulation follow up
Earlier if symptoms worsen
Discharge Instructions
Copy discharge instructions
Copy discharge instructions
Today you were seen for swelling in one leg
The main dangerous cause is a blood clot in the deep veins
Other causes include infection of the skin and soft tissues or a muscle injury
If you were diagnosed with a blood clot
Take your blood thinner exactly as prescribed
Do not miss doses
Seek care immediately for bleeding that will not stop
If you were treated for a skin infection
Take antibiotics exactly as prescribed
Mark the edge of redness and return if it spreads quickly
Activity and limb care
Elevate the leg when resting
Use compression only if advised and if no arterial circulation problem
Return to the emergency department now for
New shortness of breath
Chest pain
Coughing blood
Fainting
Severe worsening leg pain
Numbness or weakness
Cold or blue foot
Fever with rapidly spreading redness
Follow up
Arrange follow up within 2 to 3 days if infection suspected
Arrange follow up within 1 week if on blood thinner
Return sooner if symptoms worsen
References
Guidelines and decision tools
Guidelines and decision tools
American College of Chest Physicians antithrombotic therapy for venous thromboembolism disease guideline 2021
National Institute for Health and Care Excellence venous thromboembolic diseases guideline NG158 2020
American Society of Hematology guidelines for management of venous thromboembolism 2020
Infectious Diseases Society of America skin and soft tissue infections guideline 2014
Wells clinical prediction rule for deep vein thrombosis original validation 1997
Project instructions source
SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.