Septic thrombophlebitis in a HIV-positive intravenous drug user.

Septic thrombophlebitis of the pelvic veins may occur secondary to non-sterile intravenous drug injection and represents an uncommon yet life-threatening condition, most usually manifesting with persistent spiking fever and limb edema. Risk is further increased in HIV-infected people. High clinical suspicion and prompt imaging assessment with contrast-enhanced multidetector CT are necessary for correct diagnosis and staging, since early treatment prevents further complications such as systemic embolization.

INTRODUCTION

Although often life-threatening, the uncommon vascular infections are often clinically unsuspected and underdiagnosed. Septic thrombophlebitis represents a very rare condition, most usually reported to involve the dural sinuses, the internal jugular vein, the portal vein (during abdominal inflammatory processes), sometimes the pelvic veins as a complication of obstetric and gynaecological procedures.[12]

CASE REPORT

A 54-year-old male with history of human immunodeficiency virus (HIV) infection and intravenous drug abuse was hospitalized because of septic fever and lumbar pain. Clinically, edematous swelling of his external genitalia and left thigh, leg and ankle was appreciated, associated with mild pain and distal erythema. In the affected lower extremity, physical examination did not disclose significant dilatation of the superficial veins, absent peripheral pulses, or signs of arterial insufficiency.

Laboratory tests disclosed anemia (8.7g/dL), low platelet count (84.00/mmc), and markedly raised C-Reactive Protein (305 U/l). Early color Doppler study did not disclose acute abnormalities of both arterial and venous systems of the lower limbs.

Initial clinical suspicion of infectious spondylo-diskitis was excluded by negative magnetic resonance imaging (MRI) of the dorso-lumbar spine. Blood culture showed systemic methicillin-sensitive Staphylococcus aureus infection. Three days after admission, contrast-enhanced multidetector CT disclosed dilatation of the entire left femoral, external and common iliac veins with un-opacified lumen containing some gas, prominent enhancement of the venous wall and associated inflammatory stranding of the perivascular fat, findings consistent with septic thrombophlebitis [Figure 1].

Figure 1

Unenhanced multidetector computed tomography (CT) image (a) shows dilatation of left common iliac vein with intraluminal gas and inflammatory stranding of the perivascular retroperitoneal fat. Contrast-enhanced CT scan (b) depicts dilated left iliac vein with unopacified lumen, gas bubbles and prominent enhancement of the vascular wall, findings consistent with septic thrombophlebitis. Coronal reformations (c, d) document the entire extent of the left iliaco-femoral axis thrombosis, extending cranially to the caudal most portion of the inferior vena cava

Intensive medical treatment including antibiotics and anticoagulation with full-dosage low-molecular-weight heparin (6000 UI enoxaparin twice daily, prescribed for 3 months) allowed clinical resolution of sepsis and normalization of laboratory inflammatory markers during three weeks. At discharge, the iliac and femoral veins appeared patent at color doppler ultrasound. Three months later, at ambulatory follow-up visit the patient was doing well and anticoagulation was discontinued.

DISCUSSION

At least partly related to drug impurities, complications of recreational drug abuse may involve different organs (particularly the cardiovascular, respiratory, and musculoskeletal systems) and are increasingly encountered in emergency departments. Deep venous thrombosis in intravenous substance users occurs secondary to superinfection from non-sterile injection technique in the femoral veins that are used when injection sites in the arms are exhausted.[2-4] Infection with the HIV further increases the risk, because of the associated coagulation system abnormalities including increased levels of fibrinogen, D-dimer, plasminogen activator inhibitor-1, and tissue-type plasminogen activator antigen.[5]

Therefore, septic thrombophlebitis should be taken in mind as a possible cause of persistent, often spiking fever despite broad-spectrum antibiotic therapy, associated with leg edema, flank and lower abdominal pain of variable intensity. Leukocytosis and abnormal inflammatory markers may vary depending on the host immune response, and hemocultures may disclose the causing organism, most usually S. aureus.[14]

As this case demonstrates, at CT the hallmark signs of septic thrombophlebitis include vein enlargement with sharp vessel wall enhancement, partial or complete luminal non-opacification, often associated with abnormal density of the surrounding fat planes consistent with inflammatory stranding; endoluminal gas bubbles may result from superinfection or may simply reflect injected. Additionally, multiplanar reformations may help to visualize the entire extent of the venous thrombosis.[2-4]

High clinical suspicion and prompt imaging assessment with contrast-enhanced multidetector CT are imperative to diagnose this uncommon yet serious complication, to prevent further complications such as systemic embolization particularly to the lungs, brain, and musculoskeletal system.[13] Color Doppler ultrasound is often limited by meteorism and large body structure, and should be therefore reserved for monitoring treatment response.[4] Although optimal management remain controversial in literature, improved diagnosis by means of CT and adequate antibiotic and anticoagulant treatment has dramatically reduced the traditionally high mortality rates.[46]