Approach Considerations
General laboratory studies
The following studies can be performed:
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Complete blood count (CBC) - Should be sent for evidence of leukocytosis
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Chemistries - Should be sent for evidence of acidosis and electrolyte imbalance in severe infection
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Hepatologies - Should be sent if pylephlebitis is suspected
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International normalized ratio (INR/prothrombin time (PTT)- Useful in case anticoagulation is indicated
Culture
All febrile patients with suspected septic phlebitis should have blood cultures drawn. In cases of catheter-associated thrombophlebitis, cultures from peripheral and central sites should be sent for comparison. Specifically, the diagnosis of catheter-associated deep septic phlebitis is often aided by tip culture. However, the catheter should not be withdrawn in the emergency department (ED) when there is suspicion of thrombus attachment.
Evident purulent material from peripheral soft-tissue sites should be sent for Gram stain and culture. Cervical cultures and pharyngeal cultures should be sent when applicable.
Cerebrospinal fluid (CSF) culture should be sent in the context of suspected meningitis and dural vein thrombophlebitis.
Imaging Studies
CT scanning with contrast
Contrast-enhanced computed tomography (CT) scanning is generally accepted as the test of choice for most septic thrombophlebitides and should, at minimum, demonstrate a filling defect within the involved vessel. In the context of positive blood cultures, this finding clinches the diagnosis. [31]
CT scanning is particularly useful in the evaluation of portal, pelvic, and internal jugular vein thrombophlebitis, [32] as it may also demonstrate the inciting inflammatory process.
Thrombi with surrounding inflammatory changes are noted on CT scans in cases of septic thrombophlebitis in the superior and inferior vena cava. [33]
Data show detection rates comparable to magnetic resonance (MR) venography for multidetector-row CT angiography in the diagnosis of all types of dural sinus thrombosis. [34]
MRI
Though less data on the efficacy of magnetic resonance imaging (MRI) exist, it is generally accepted as a useful diagnostic modality for most septic thrombophlebitides.
Intra-abdominal thrombophlebitides are well visualized with MRI and show intraluminal thrombus and abnormal thickening and enhancement of the affected vessel's wall. [35, 36]
MR with MR venography is considered the most sensitive noninvasive modality for the imaging of the dural sinuses. [34]
Ultrasonography
Ultrasonography can show venous thrombus and is diagnostic of thrombophlebitis in the setting of positive blood cultures. [37] Ultrasound may also be helpful on the rare occasions of frank abscess in the adjacent tissues.
Since the internal jugular vein is easily accessible, sonography is often helpful in the diagnosis of Lemierre disease. [8]
Periportal collaterals, aeroportia, and liver abscesses may be identified by ultrasonography in the setting of pyelophlebitis. [32]
Ultrasonography was found to be inadequate for septic pelvic thrombophlebitis [35] and cannot be used for the diagnosis of dural vein thromboses owing to poor wave penetration though bone.
Angiography
Angiography can be helpful in the diagnosis of catheter-related thrombophlebitis because it will demonstrate the fibrin sheath adhered to the catheter tip.
