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Paper text:
a 49-year - old man presented with a 2-day history of worsening abdominal pain and nonbloody diarrhea .
he had undergone his second cycle of radical chemotherapy ( cisplastin , doxitacel , and 5-fluorouracil ) 4  days prior to admission for a newly diagnosed postcricoid esophageal squamous cell carcinoma . on arrival
, he was found to be peripherally vasoconstricted , blood pressure was 60/40  mmhg and heart rate was 130 bpm .
he was apyrexial and abdominal examination revealed a rigid abdomen with severe generalized rebound tenderness and quiet bowel sounds .
a full blood revealed pancytopenia ( wcc 0.9 , hb 93 , plt 115 ) and arterial blood glas showed metabolic acidosis with a lactate of 6.5  mmol / l .
he underwent an urgent contrasted ct abdomen and pelvis study ( fig.1 ) , which revealed extensive gas within the portal venous system and in the superior mesenteric branches .
a conservative management strategy was adopted and the patient was treated with intravenous piperacillin / tazobactam , intravenous fluids , and analgesia .
he made a remarkable recovery over a period of 72  h. a repeat ct study after 2  weeks showed complete radiologic resolution of the gas within the liver .
the rapid improvement has led us to suspect that the cause of the reversible bowel ischemia was likely cisplatin - induced bowel toxicity .
the main radiological differential is pneumobilia , air in the biliary tree . differentiating hepatic portal venous gas ( hpvg ) and pneumobilia
, the branching radiolucency often extends to within 2  cm of the liver capsule due to the centrifugal flow of portal venous blood . in pneumobilia ,
the air is situated centrally to the liver hilum due to the opposite direction of bile flow 1 .
hpvg can be an indicator of significant intra - abdominal pathology and bowel ischemia is the most common causative etiology for hpvg .
traditionally , the detection of hpvg in patients with ischemic bowel is associated highly with transmural necrosis ( 90% of cases ) 2 and predicts a high risk of mortality ( up to 85% ) . with the advent of better imaging techniques , an increasing number of cases of hpvg secondary to various causes such as inflammatory bowel disease , gastric ulcer , and intra - abdominal sepsis
a study of 182 cases of hpvg revealed an overall mortality rate of 39% 3 .
key clinical messagedifferentiating hepatic portal venous gas ( hpvg ) and pneumobilia on the ct scan can be accomplished by comparing the pattern of intrahepatic air spread . 
 hpvg can be an indicator of significant intra - abdominal pathology and bowel ischaemia is the most common causative etiology for hpvg .