hepatic portal venous gas ( hpvg ) was first described in 1955 in an infant with fatal necrotizing enterocolitis , and subsequently reported in adults .
it is a rare condition with numerous etiologies , including bowel infarction , necrotizing enterocolitis , closed loop obstructions , acute hemorrhagic pancreatitis , granulomatous enterovenous fistula , pseudomembranous colitis , gastric ulcer , and gastric emphysema .
intracorporeal factors such as damaged mucosa and bowel distension may be responsible for the passage of gas into the portal system .
reports of iatrogenic causes , such as barium enema and endoscopy , have recently increased , particularly among patients with inflammatory bowel disease . 
  here ,
we describe a 54-year - old woman with crohn s disease who developed hpvg following colonoscopy by double balloon endoscopy , and was successfully managed conservatively .
a 54-year - old - woman presented to a general practitioner with a two - day history of abdominal pain and nausea .
abdominal radiography on initial consultation revealed niveau formation , leading to a diagnosis of ileus , and she was hospitalized in a local hospital under conservative treatment for two days .
history included crohn s disease , which was pathologically diagnosed in 1977 following partial ileectomy for acute lower abdominal pain .
she subsequently underwent two further partial ileectomies , as well as hysterectomy for uterine myoma in 1998 and ileocolostomy in 2003 .
her compliance with regular follow - up visits and medication for crohn s disease was poor .  
she was subsequently transferred to our hospital for further examination and treatment . at the time of transfer ,
assessment did not identify niveau formation , and her ileus was improved ( figure 1 ) .
gastrografin examination of the small intestine on day 3 of hospitalization revealed constriction of the terminal ileum for about 10 cm from the site of the previous operative anastomosis ( figure 2 ) .
the cause of the ileus was constriction due to the exacerbation of crohn s disease .
double balloon endoscopy ( dbe ) for the ileum and colon did not reveal mucosal damage , and revealed the stricture at the anastomotic site due to the previous operation ( figure 3 ) .
after endoscopy , we checked the abdominal ct to aid in research into virtual endoscopy ( figure 4 ) .
although she did not report abdominal pain following endoscopy , the abdominal ct revealed multiple small tubular lucencies in the periphery of the liver , indicating the presence of hpvg .
given the lack of symptoms ( no fever or abdominal pain ) , we selected conservative therapy with the cessation of oral ingestion , and a started a two - day prophylactic course of antibiotics .
three days after examination , she had no symptoms , so we started enteral feeding of an elemental diet .
abdominal ct at the time of transfer to our hospital showed no niveau formation , and the amelioration of ileus .
gastrografin examination of the small intestine revealed constriction of the terminal ileum for about 10 cm and the ileum - colon ( check ) anastomosis ( arrows ) .
the anastomotic region ( arrows ) of a previous side - to - side anastomosis .
no mucosal lesions were found . computed tomography demonstrated gas in the peripheral branches of the portal vein following colonoscopy . computed tomography six days after examination did not identify hepatic portal venous gas .
the finding of hpvg can be associated with either benign or critical conditions that require immediate surgery .
hpvg is speculated to arise from two sources , the escape of bowel gas as a result of increased pressure in the bowel lumen or in an abscess , followed by circulation into the liver ; or the presence of gas - forming bacteria in the portal venous gas system and passage of gas into the circulation .
hpvg appears on plain abdominal radiography or ct as linear radiolucencies extending to within 2 cm of the periphery of the liver .
in contrast to biliary air , which is central and almost never extends to the periphery , gas in the portal venous system is likely transported to the small peripheral branches in the liver by the centrifugal flow of the portal venous blood .
although most cases of hpvg in critical conditions are caused by mesenteric vascular occlusion and subsequent bowel necrosis , it can also arise due to various other conditions .
benign causes for hpvg include administration of fluids via an umbilical catheter , barium enema , and colonoscopy .  
the present hpvg case was a crohn s disease patient , and hpvg occurred following colonoscopy .
this case is the 12th case of hpvg associated with inflammatory bowel disease ( ulcerative colitis and crohn s disease ) following examination of colon reported to date ( table 1 ) . of these , five patients were asymptomatic and required no specific treatment , apart from prophylactic antibiotics in several .
one patient experienced abdominal pain and received antibiotics before finally recovering under conservative therapy . for patients with hpvg who are asymptomatic ,
the bowel wall in inflammatory bowel diseases such as ulcerative colitis and crohn s disease is often severely damaged .
it has been speculated that elevated intraluminal pressure during colonic diagnostic procedures or due to constriction of the intestine can permit bowel gas or gas - forming bacteria to access the portal venous circulation through microscopic mucosal injury , and hpvg associated with inflammatory bowel disease often results from barium enema or colonoscopy . in the absence of peritoneal signs or free air , hpvg is a benign finding in patients with inflammatory bowel disease following diagnostic studies of the intestine .  
the recent development of endoscopy equipment , including double balloon endoscopy , has facilitated detailed observation of the intestinal tract , and generally increased the number of examinations in patients with inflammatory bowel disease .
because imaging tests such as ct which identify hpvg are not routinely obtained after examination , there may be more asymptomatic hpvg cases which are not diagnosed .
in present case , if we had not conducted research into virtual endoscopy , the abdominal ct might not have been carried out .
immediate use of imaging tests is required if the patient has subjective symptoms , such as abdominal pain and high fever .
although hpvg often improves under observation and is rarely serious situation , adverse outcomes could also occur , mandating that hpvg be considered as a complication of examinations of the colon or small intestine in inflammatory bowel disease .
clinical features , study , diagnostic modality , treatment , and outcome in 12 patients with inflammatory bowel disease with hepatic portal venous gas associated with examination of colon .
 abstracthepatic portal venous gas is a rare condition that occurs when intraluminal gas or gas produced by intestinal bacteria enters the portal venous circulation . 
 it has recently been recognized as a rare complication of colon procedures by endoscopy or barium enema . 
 given the frequency of these procedures in patients with inflammatory bowel disease , hepatic portal venous gas may occur more frequently in these patients than previously reported . here , 
 we report a woman with crohn s disease who developed hepatic portal venous gas following colonoscopy who was treated with conservative therapy . 
INTRODUCTION
CASE REPORT
DISCUSSION