What is the etiology of Transjugular Intrahepatic Portosystemic Shunt (TIPS) infection?

Etiology of TIPS Infection (Endotipsitis)

TIPS infections are primarily caused by bacterial or fungal pathogens that colonize the stent, with a higher risk in patients with dilated intrahepatic bile ducts in the tract of the TIPS due to potential passage through infected bile ducts. 1

Microbial Etiology

• Gram-positive bacteria are the most common causative agents (approximately 58% of cases), particularly in early infections occurring within 120 days of TIPS placement 2
• Gram-negative microorganisms account for approximately 32% of infections 3
• Fungal pathogens, particularly Candida species, are responsible for about 10% of cases, though they are less frequently reported in the literature 4, 3
• Polymicrobial infections can occur, especially in cases where there is communication between the TIPS and an infected biliary tree 5

Risk Factors and Pathogenesis

• The presence of dilated intrahepatic bile ducts in the tract of TIPS significantly increases infection risk due to passage through potentially infected bile ducts 1
• TIPS/biliary fistula formation can lead to persistent polymicrobial infection resistant to antibiotic therapy 5
• Technical difficulties during TIPS placement and subsequent shunt thrombosis are associated with increased infection risk 6
• Primary sclerosing cholangitis (PSC) patients may have a higher risk due to their underlying biliary disease 1
• The overall incidence of endotipsitis is estimated at 1.33% in patients undergoing the TIPS procedure 3

Clinical Presentation and Timing

• Most cases (88%) occur more than one month after the TIPS procedure 3
• The most common presentation includes fever and primary bacteremia or fungemia without another identifiable source 3, 2
• Early infections (<120 days post-procedure) are more commonly caused by staphylococci and other gram-positive bacteria 2
• Late infections (>120 days post-procedure) can occur years after the initial procedure 2

Diagnostic Considerations

• Diagnosis requires a high index of suspicion and is based on persistent bacteremia or fungemia in a patient with TIPS when other sources of infection have been ruled out 2
• Diagnostic criteria include:
  • Persistent positive blood cultures in a patient with TIPS
  • No other identifiable source of infection
  • Either shunt occlusion, vegetation on the shunt, or bacteremia in the presence of a patent shunt 2
• Comprehensive imaging workup is necessary to rule out other sources of infection, including ultrasonography, CT, and echocardiography 2

Prevention

• While evidence is limited, prophylactic antibiotics during the initial TIPS procedure are common practice despite lack of strong supporting evidence 2
• TIPS may be contraindicated in cases of dilated intrahepatic ducts in the tract of TIPS due to the enhanced risk of infection 1

Clinical Implications

• Endotipsitis carries significant morbidity and mortality if not properly diagnosed and treated 4, 2
• In patients with PSC who require TIPS, the procedure should be approached with caution due to the increased risk of infection when passing through infected bile ducts 1
• Liver transplantation may need to be delayed until the infection is cleared 6

Understanding the etiology of TIPS infection is crucial for prevention, early diagnosis, and appropriate management of this rare but serious complication.