Can Femoral DVT Cause Intermittent Fever?
Yes, femoral DVT can cause fever, including intermittent fever, though this occurs in a minority of patients and should prompt consideration of DVT as a potential etiology when other common causes have been excluded.
Prevalence and Clinical Significance
- Fever occurs in approximately 5% of patients with acute DVT at presentation, based on data from the RIETE registry of 14,480 patients with symptomatic DVT 1
- DVT should be considered in the differential diagnosis of fever of unknown origin (FUO) after more common causes have been excluded, as lower extremity ultrasound has been incorporated into FUO workup algorithms 2
- In a focused study of FUO patients, 6% (5 of 89 patients) had DVT as the probable cause of their fever, with 4 patients having iliofemoral DVT specifically 3
Diagnostic Criteria for DVT-Related Fever
When DVT is suspected as the cause of fever, the following criteria should be met 3:
- Temperature greater than 38.4°C on multiple occasions
- Positive venous duplex ultrasound demonstrating acute DVT
- Fever resolution within 7 days of initiating anticoagulation therapy (this is the key diagnostic feature)
Clinical Characteristics
- Femoral DVT (proximal DVT) is more likely to present with fever than distal DVT, as 4 of 5 FUO cases in one series had iliofemoral involvement 3
- The fever pattern can be intermittent rather than continuous 3
- Fever need not be accompanied by pulmonary hemorrhage or infarction, as demonstrated in pulmonary embolism studies where fever occurred in 14% of patients without other fever sources 4
Prognostic Implications
Patients with DVT who present with fever have significantly worse outcomes 1:
- Higher 30-day mortality (5.8% vs 2.9%; odds ratio 2.6)
- Increased risk of pulmonary embolism (0.7% vs 0.1%)
- Increased risk of fatal infection (1.1% vs 0.3%)
- Multivariate analysis confirms fever as an independent predictor of mortality (hazard ratio 2.00)
Diagnostic Approach
Duplex ultrasound of the lower extremity is the appropriate initial imaging modality for suspected DVT in patients with unexplained fever 2, 5:
- Real-time compression ultrasound identifies failure of complete vein wall compression
- Doppler evaluation assesses flow patterns and can detect proximal obstruction
- Ultrasound has 94.2% pooled sensitivity and 93.8% pooled specificity for proximal DVT 2
Critical Clinical Pitfall
Approximately one-third of DVT patients are asymptomatic, meaning fever may be the only presenting sign 2. Therefore:
- Do not exclude DVT from the differential based solely on absence of leg pain, swelling, or tenderness
- Clinical prediction scores (Wells score) combined with D-dimer are less reliable in certain populations and should not be used alone to exclude DVT 2
- Consider DVT screening in high-risk immobilized patients even without classic DVT symptoms 2
Treatment Confirmation
If DVT is identified as the cause of fever, temperature should normalize within a few days of heparin therapy 3. This therapeutic response serves as retrospective confirmation of the diagnosis and helps distinguish DVT-related fever from other causes such as concurrent infection.