An unexpected cause of persistent bacteraemia and portomesenteric venous gas

We report the case of a 59-year old man with portomesenteric venous gas (PMVG) due to inferior mesenteric vein fistulization caused by sigmoid diverticulitis with an unusual evolution. The patient initially presented with classic symptoms of lower abdominal pain and fever. Diagnosis of uncomplicated sigmoid diverticulitis was confirmed on computed tomography (CT) for which intravenous antibiotics were initiated. Hemocultures were positive for omnisensitive Escherichia Coli, but despite adequate intravenous antibiotic therapy, episodes of bacteraemia persisted and hemocultures remained positive. Repeat CT scan demonstrated regression of inflammation without signs of abcedation or perforation consistent with clinical findings. Endocarditis was excluded with a normal transoesophageal echocardiography. Finally, positron emission tomography-computed tomography (PET-CT) suspected a colovenous fistula and the presence of PMVG. The patient was successfully treated with laparoscopic sigmoidectomy. This case report summarises the diagnostic pathway and aims for higher awareness of non-ischemic PMVG causes.