Clinical History
A 34-year-old homeless male was hospitalized because of sudden onset of headache and spiking fever. Physical examination revealed dehydration, tenderness and enlargement of his right thigh, marked oedematous, reddish inguinal skin thickening with mixed bloody and purulent drainage. He admitted intravenous injection of cocaine at the groin the day before.
Imaging Findings
Bedside colour Doppler ultrasound (not shown) suggested right iliac-femoral obstructive thrombosis. Marked leukocytosis and increased C-reactive protein (187 mg/l) were present.
Urgent contrast-enhanced body MDCT confirmed non-opacified right common, external iliac and femoral veins with prominent vessel wall enhancement, some endoluminal gas bubbles indicating septic thrombophlebitis. The injection site was identifiable (Fig. 1). Pleural effusions and lung base consolidations were detected, along with mediastinal adenopathies and subpleural lesions with central cavitations consistent with septic emboli (Fig. 2).
Intensive treatment was started, including antibiotics, hydration, oxygen and low-molecular-weight heparin anticoagulation. Blood and groin pus cultures were positive for multiple organisms. Previously unknown HIV infection was diagnosed. Follow-up MDCT showed iliaco-femoral axis with decreased caliber and persistent vessel wall enhancement (Fig. 3), regressed basal consolidations and lung septic emboli as residual cavitations with thin walls, reduced adenopathies and persistent effusions (Fig. 4). Clinical and laboratory improvement required 7 weeks of hospitalisation.
Discussion
Increasingly encountered in Emergency Department patients, the wide spectrum of acute and chronic medical complications of recreational drug use may involve different organs, particularly the cardiovascular, respiratory, musculoskeletal, and central nervous systems [1].
Among these, septic thrombophlebitis is a not-infrequent yet life-threatening occurrence in intravenous substance users, that results from non-sterile injection technique, most usually in the femoral veins at the groin that are used when injection sites in the arms are exhausted [1-3]. The risk is further increased by Human Immunodeficiency Virus (HIV) infection, because of the combined effect of immune suppression and the associated coagulation system abnormalities [4].
In the appropriate clinical context, deep vein septic thrombophlebitis should be suspected as a possible cause of persistent, often spiking fever despite broad-spectrum antibiotic therapy, associated with leg oedema, flank or lower abdominal pain, variable leukocytosis and abnormal inflammatory markers. Staphylococcus aureus is the most common causative organism identified by haemocultures [3, 5].
As this case demonstrated, colour Doppler ultrasound and contrast-enhanced multidetector CT with multiplanar reformations effectively detect the presence, stage, and the extent of deep septic thrombophlebitis. The involved veins appear enlarged with partially or entirely non-opacified lumen. Superinfection is suggested by intense vessel wall enhancement, endoluminal gas bubbles, and sometimes by abnormal inflammatory hyperdense “stranding” of the surrounding fat planes [1-3].
In recent years, imaging diagnosis and combined antibiotic treatment and heparin anticoagulation allowed a significant decrease of associated mortality rate [3, 6].
Additionally, radiologists should remember that intravenous drug abuse is a multisystem disorder including vascular and infective complications affecting different organ systems, often synchronously. As exemplified by this patient, one of the most common manifestations is represented by septic pulmonary embolisation, resulting from thrombus detachment and haematogenous bacterial dissemination. Lung involvement shows up in CT as peripheral consolidations and ill-defined abscess-like nodules with frequent central cavitation [1, 4].
In conclusion, high clinical suspicion and prompt imaging assessment are needed for timely diagnosis and treatment of these life-threatening condition, and to prevent further complications such as secondary “metastatic” cardiac valvular, arterial, brain, and musculoskeletal infections [1, 2].
Differential Diagnosis List
Iliaco-femoral infected thrombophlebitis, lung septic embolisation from intravenous drug injection
Aseptic venous thrombosis
Pulmonary thromboembolism
Sepsis
Pneumonia
Systemic mycobacterial infection
Pseudo-aneurysm from arterial puncture
Mycotic aneurysm
Final Diagnosis
Iliaco-femoral infected thrombophlebitis, lung septic embolisation from intravenous drug injection
