Pylephlebitis

Pylephlebitis is septic thrombophlebitis of the portal vein and its tributaries, usually from an intra-abdominal infection in the portal drainage. It combines bacteraemia with portal venous thrombosis.

It is rare, and mortality is 10% to 30% with delayed treatment. Diverticulitis and appendicitis are the commonest sources.

Sources are diverticulitis, appendicitis, inflammatory bowel disease, pancreatitis, cholangitis and cholecystitis, liver abscess, pelvic infection, haemorrhoid procedures and surgery.

Organisms are Escherichia coli, Bacteroides fragilis and other anaerobes, Streptococcus species, Klebsiella and enterococci. Infection is often polymicrobial.

Pathophysiology.

Infected venous drainage seeds the portal vein, causing endothelial injury, thrombosis and bacterial multiplication within the thrombus. Septic emboli reach the liver, causing abscesses.

Fever with rigors, abdominal pain (right upper quadrant or lower), jaundice, nausea, hepatomegaly and sepsis. Complications are liver abscess, extension to mesenteric veins and bowel ischaemia, portal hypertension and cavernous transformation.

Red flags.

• Sepsis or shock.
• Abdominal pain with rising lactate (mesenteric ischaemia).
• Jaundice with liver abscess.

CT with contrast (portal phase) or Doppler ultrasound shows a filling defect in the portal or mesenteric vein, with a source of infection and liver abscesses. Blood cultures (positive in most), full blood count, C-reactive protein, liver enzymes and lactate are sent. Thrombophilia testing and assessment for malignancy are considered once infection is controlled.

Differential diagnosis.

• Bland portal vein thrombosis.
• Cholangitis.
• Liver abscess alone.
• Tumour thrombus from hepatocellular carcinoma.
• Budd-Chiari syndrome.
• Mesenteric ischaemia.

Give intravenous antibiotics immediately with source control (drain abscesses, resect or drain the source), and anticoagulate unless contraindicated.

• Piperacillin-tazobactam: 4.5 g IV every 6 hours; 4 to 6 weeks in total, with oral stepdown by culture results; maximum 18 g daily; monitor renal function, blood counts and cultures; reduce for creatinine clearance under 40 mL/min.
• Ceftriaxone plus metronidazole (alternative): ceftriaxone 2 g IV once daily, with metronidazole 500 mg IV or orally every 8 hours; 4 to 6 weeks; maximum ceftriaxone 4 g daily and metronidazole 1.5 g daily; monitor rash, counts and neuropathy; reduce metronidazole to 500 mg every 12 hours in severe hepatic impairment.
• Enoxaparin: 1 mg/kg subcutaneously every 12 hours (or 1.5 mg/kg once daily); 3 to 6 months, and longer with a persistent prothrombotic state; maximum 150 mg for each dose; monitor platelets, bleeding and anti-Xa in renal impairment or extreme weight; use 1 mg/kg once daily when creatinine clearance is under 30 mL/min.

Anticoagulation reduces thrombus extension and lowers the risk of cavernous transformation. Treat varices if portal hypertension develops.

Monitoring. Blood cultures until negative, inflammatory markers, repeat imaging at 2 to 4 weeks and at the end of treatment.

Referral and escalation. Infectious diseases, hepatology or hepatobiliary surgery, and interventional radiology; critical care for sepsis.