Thrombophlebitis from Insect Bites
Insect bites can rarely cause thrombophlebitis, with documented cases including deep vein thrombosis following wild bee stings due to inflammatory mediators in the venom that can cause endothelial injury and promote thrombosis. 1
Pathophysiology and Risk
Insect venom, particularly from bees, can induce the secretion of inflammatory mediators including:
- Histamine
- Phospholipase A1
- Thromboxane
These substances can lead to:
- Vasoconstriction
- Endothelial injury
- Microcirculation deterioration
- Subsequent thrombosis 1
While thrombophlebitis is typically associated with:
- Venous valvular insufficiency
- Pregnancy
- Infection
- Prothrombotic conditions (including malignancy) 2
It can also occur after trauma or other causes that create an initial break in the skin 3.
Clinical Presentation
When thrombophlebitis occurs after an insect bite, patients may present with:
- Pain, erythema, and tenderness at the site of inflammation
- A hardened, tender superficial vein
- Significant pain with inflammation 4, 2
Diagnosis and Evaluation
For suspected thrombophlebitis following an insect bite:
- Clinical examination is the primary diagnostic method
- Ultrasonography is useful to check for concomitant deep vein thrombosis (DVT) 5
- Consider evaluation for underlying conditions if thrombophlebitis appears without clear precipitating factors 4, 6
Treatment Approach
For Uncomplicated Superficial Thrombophlebitis:
- Compression with bandages or elastic stockings
- NSAIDs for pain and inflammation
- Low-molecular-weight heparin in high-prophylactic doses 5
For Complicated Cases or DVT:
- Full anticoagulation is mandatory if DVT is present
- Consider thrombectomy for thrombus propagation into deep veins 5
Antibiotic Considerations:
- Routine antibiotic prophylaxis is not indicated for uncomplicated insect stings 7
- Consider antibiotics if signs of infection develop or in high-risk patients 7
Antibiotic options if infection develops:
- Amoxicillin-clavulanate: 875/125 mg twice daily
- Cephalexin: 250-500 mg four times daily
- Clindamycin: 300-400 mg three times daily (for penicillin-allergic patients) 7
Prevention and Follow-up
For patients with insect bites:
- Proper wound care including cleaning with soap and water
- Remove stinger immediately if present
- Apply cold compresses to reduce pain and swelling 7
- Monitor for signs of infection or thrombosis development
Important Caveats
- While superficial thrombophlebitis is usually self-limited, it can occasionally progress to involve the deep venous system and potentially cause pulmonary embolism 2, 5
- Risk factors for complications include those known for DVT 5
- Thrombophlebitis in non-varicose veins without clear precipitating factors may warrant investigation for underlying systemic diseases 6
- Documented cases of vascular thrombosis after insect stings are rare but potentially serious 1