Pylephlebitis: A Systematic Review on Etiology, Diagnosis, and Treatment of Infective Portal Vein Thrombosis

Abstract

Pylephlebitis, defined as infective thrombophlebitis of the portal vein, is a rare condition with an incidence of 0.37-2.7 cases per 100,000 person-years, which can virtually complicate any intra-abdominal or pelvic infections that develop within areas drained by the portal venous circulation. The current systematic review aimed to investigate the etiology behind pylephlebitis in terms of pathogens involved and causative infective processes, and to report the most common symptoms at clinical presentation. We included 220 individuals derived from published cases between 1971 and 2022. Of these, 155 (70.5%) were male with a median age of 50 years. There were 27 (12.3%) patients under 18 years of age, 6 (2.7%) individuals younger than one year, and the youngest reported case was only 20 days old. The most frequently reported symptoms on admission were fever (75.5%) and abdominal pain (66.4%), with diverticulitis (26.5%) and acute appendicitis (22%) being the two most common causes. Pylephlebitis was caused by a single pathogen in 94 (42.8%) cases and polymicrobial in 60 (27.2%) cases. However, the responsible pathogen was not identified or not reported in 30% of the included patients. The most frequently isolated bacteria were Escherichia coli (25%), Bacteroides spp. (17%), and Streptococcus spp. (15%). The treatment of pylephlebitis consists initially of broad-spectrum antibiotics that should be tailored upon bacterial identification and continued for at least four to six weeks after symptom presentation. There is no recommendation for prescribing anticoagulants to all patients with pylephlebitis. However, they should be administered in patients with thrombosis progression on repeat imaging or persistent fever despite proper antibiotic therapy to increase the rates of thrombus resolution or decrease the overall mortality, which is approximately 14%.

Keywords: Bacteroides; Escherichia coli; Streptococcus; anticoagulant; appendicitis; diverticulitis; portal vein; portal vein thrombosis; pylephlebitis.

Figure 1

Identification of studies via databases and registers following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

Figure 2

Yearly distribution of published case reports or case series involving pylephlebitis between 1971 and 2022.

Figure 3

A 35-year-old male with fever and severe abdominal pain was admitted to the emergency department of Trieste University Hospital. Ultrasound with color flow Doppler images (a,b) shows acute inflammation of the appendix (empty arrow in (a)) and echogenic material inside an intrahepatic branch of the portal vein without color flow signal (solid arrow), due to thrombosis. Contrast-enhanced CT images in axial (c) and coronal (d) plains confirm a filling defect in a right intrahepatic portal vein branch (solid arrows), with transient hepatic attenuation differences—THAD—(* in c) due to hepatic arterial compensatory flow in the corresponding segment.

Figure 4

A 68-year-old male was admitted to the emergency department of Trieste University Hospital with symptoms and laboratory tests consistent with hepato-cholangitis. Contrast-enhanced CT image (a) shows the absence of opacification of the left intrahepatic portal vein branch (solid arrow) due to portal vein thrombosis and mild biliary dilation (thin arrow). Coronal T2 weighted MR image (b) demonstrates multiple filling defects (empty arrow) in the distal common bile duct consistent with choledocholithiasis and biliary sludge.

Figure 5

Summary of main findings on pylephlebitis in terms of incidence, pathogens, symptoms, underlying cause, and treatment.