What does portomesenteric vein gas mean?

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Portomesenteric vein gas (PMVG) is not a disease, but a rare ominous radiologic sign .... Pafient with occlusion of the superior mesenteric artery. SMA. Defect in ...
What does portomesenteric vein gas mean? B Mar5n(1), F Desmots(1), N Couppey(1), I Boulay-ColeCa(2), C Gabaudan(1), M Zins(2), Y Geffroy(1) (1) Service de Radiologie, H.I.A. Laveran, Marseille (2) Groupe hospitalier Saint-Joseph, Paris

Introduc5on •  The presence of gas in the portal vein was first describe by Wolfe and Evens in 1955 in infants with necro5zing enterocoli5s and by Susman and Senturi in 1960 in adults. •  Portomesenteric vein gas (PMVG) is not a disease, but a rare ominous radiologic sign, associated with numerous underlying abdominal diseases, ranging from benign causes to poten2ally lethal diseases. •  PMVG is most commonly caused by mesenteric ischemia. •  Although the cause of PMVG appears to be mul2factorial, the pathogenesis is s5ll not fully understood.

Introduc5on •  PMVG is not by itself a surgical indica5on. •  The treatment depends mainly of the underlying disease; the prognosis is related to the pathology itself and not influenced by the presence of PMVG. •  Currently, the increased used of CT scan allows early and highly detec5on of small PMVG and also the underlying disease. •  It is important to dis5nguich benign causes from life-threatening causes of PMVG in order to avoid unneccessary surgical explora5on in non ischemic condi5ons.

Plan o  Pathogenic mechanisms o  CT findings and differen5al diagnosis o  Surgical causes of PMVG 1. Bowel necrosis !  Acute mesenteric ischemia !  Mechanical obstruc5on 2. Others surgical causes of PMVG o  Benign causes of PMVG

Pathogenic mechanisms Precise mechanism s5ll uncertain Mul5factorial : 2 or all 3 condi5ons are present in many cases

Intes2nal wall altera2ons Bowel distension

Sepsis

Idiopathic

PMVG is idiopathic in approximately 15% of cases (organ transplantation, pulmonary diseases…)

Pathogenic mechanisms Precise mechanism s5ll uncertain Mul5factorial : 2 or all 3 condi5ons are present in many cases

Intes2nal wall altera2ons

!  !  !  ! 

Acute mesenteric ischemia +++ Perforated tumor Ulcer Inflammatory bowel disease(Ulcera2ve coli2s,Crohn disease), coli2s…

Which facilitates the passage of intraluminal gas into the portomesenteric system

Acute mesenteric ischemia with bowel necrosis is the most common cause of portomesenteric vein gas

Pathogenic mechanisms Precise mechanism s5ll uncertain Mul5factorial : 2 or all 3 condi5ons are present in many cases

IATROGENIC

NON IATROGENIC

Intes2nal !  Blunt trauma and wall barotrauma

altera2ons

!  Paraly2c ileus, mechanical obstruc2on (obstruc2ve tumor, volvulus)

Bowel distension

!  Endoscopic procedures : gastrostomy, sclerotherapy for esogastric varices, endoscopic retrograde cholangiopancreatography, colonoscopy !  Jejunal feeding tube !  Barium enema (given up)

Minimal mucosal disruption may result from increased intraluminal pressure secondary to bowel distension that allows intraluminal gas to become intravascular

Pathogenic mechanisms Precise mechanism s5ll uncertain Mul5factorial : 2 or all 3 condi5ons are present in many cases 3 theories 1)  PMVG results from sepJcemia in branches of the mesenteric and Intes2nal portal veins. wall altera2ons 2)  PMVG results from increased intraluminal fermentaJon of carbohydrates due to bacteria. Bowel 3)  Mesocolic abcess causes distension intramesocolic intesJnal perforaJon that dissects between the peritoneal leaflets of the mesocolon and creaJng access to mesocolic veins.

!  Diver2culi2s Sepsis

Abdominal abcess Cholecys22s and cholangi2s Appendici2s Pancrea22s Coli2s (inflammatory, pseudomembranous, candida infec2on in HIV) !  Abdominal tuberculosis !  !  !  !  ! 

Portal vein gas •  Small and numerous •  Tubular areas of decreased aCenua5on in the periphery of the liver •  Predominantly in the le^ lobe •  Branching area of low aCenua5on extending to within 2 cm of the liver capsule

INTRA HEPATIC GAS !  Portal vein gas !  Pneumobilia

Pneumobilia •  Air located centrally •  Does not extend to within 2 cm of the liver capsule •  Confluence of air in the common hepa5c duct •  Le^ lobe predilec5on •  Larger and less numerous than the portal vein gas

CAUSES ! Iatrogenic+++ : sphincterotomy, biliary-enteric surgical anastomosis ! Biliary-enteric fistula : gallstone ileus, ulcer or neoplasm ! Anaerobie cholangi2s, emphysematous cholecys22s ! Incompetent sphincter of Oddi ! Hepa2c trauma

Pneumobilia versus Portal vein gas

•  Large tubular areas of decreased aCena5on •  Le^ lobe predilec5on •  Central loca5on of the air •  Not many branches •  Respect the capsular area

•  Thin tubular areas of decreased aCenua5on •  Le^ lobe predilec5on •  In the periphery of the liver •  Numerous branches "  « Dead tree » aspect if massive

Mesenteric vein gas •  Gas in the small mesenteric veins = tubular or branches areas of decreased aCenua5on in the mesenteric border of the bowel. •  Portal vein gas and mesenteric vein gas most commonly associated.

!  Pneumoperitoneum an2mesenteric border+++ !  Air in the appendix

Mesenteric vein gas



Pneumoperitoneum an2mesenteric border+++ Air in the appendix

• 

Surgical causes of PMVG 1. BOWEL NECROSIS Most common cause of PMVG (70% of cases)

•  Several causes at the origin of this bowel necrosis: !  Acute mesenteric ischemia : arterial +++ >> venous > non occlusive Life-threatening condiJon with a reported mortality rate of 50 to 90% depending on the cause and the severity of bowel ischemia !  Mechanical obstruc5on bowel : - obstruc2ve diges2ve tumor - closed-loop obstruc5on by an adhesive band or internal/external hernia => excepJonal situaJon of PMVG

• 

Acute mesenteric ischemia (AMI) ARTERIAL occlusion +++ 60-75% AMI !  Thrombo-embolism

Arterial embolism (40-50%) Arterial thrombosis (20-30%)

•  NON OCCLUSIVE mesenteric ischemia 20-30% AMI •  VENOUS occlusion 5-15% AMI Possibility of an arterial ischemia if persistent venous ischemia •  CT findings in mesenteric ischemia include : !  Bowel wall thickness !  Bowel wall aCenua5on !  Portomesenteric vein gas

!  Intes5nal pneumatosis !  Mesenteric thrombosis !  Bowel distension

Most of these signs are non specifc and must occur in associaJon with clinically suspected acute mesenteric ischemia to be considered significant for this disease enJty.

Bowel wall

Mesenteric vessels

Mesentery

Dilata2on of the bowel lumen

CT findings in acute mesenteric arterial occlusion

Bowel wall

Mesenteric vessels

Mesentery

Dilata2on of the bowel lumen

CT findings in acute mesenteric arterial occlusion # Thinning of the bowel wall !  Absent or diminished contrast enhancement # Decreased or absent contrast enhancement highly specific for acute mesenteric ischemia

=> highly specific

Caecal wall very thinned with diminished of enhancement

Caecal mesenteric infarc.on

Absence of contrast enhancement with « paper-thin wall »

Mesenteric ischemia due to thrombus in the superior mesenteric artery

Bowel wall

Mesenteric vessels

Mesentery

Dilata2on of the bowel lumen

CT findings in acute bowel ischemia # Pneumatosis intes2nalis (PI) Pneumatosis intes5nalis = low density linear or bubbly paCern of gas in the gastrointes5nal wall. !  Circular form of PI

Usually benign and most o^en seen with !  Linear form of PI pneumatosis cys5c intes5nalis (PCI) Transmural bowel infarc5on in 90% of cases Bubble form of PI !  Pneumatosis intesJnalis not always synonym of bowel ischemia Transmural bowel infarc5on in 70% of cases !  Combina2on of both linear and bubbly bowel wal gas Benign causes : infecJous, inflammatory, iatrogenic, bowel obstrucJon, ulcers, asthma, emphysema, medicaJons… Linear PI more frequently seen than bubbly PI in paJents with transmural bowel infarcJon* *Kernagis et al. Pneumatosis intes5nalis in pa5ents with ischemia.AJR 2003

Bowel wall

Mesenteric vessels

Mesentery

Dilata2on of the bowel lumen

Pneumatosis cystoides intes2nalis (PCI) • # Uncommon condi5on in which submucosal or subserosal gas cysts are found Idiopathic : up to 15 % of cases and usually involves the colon in the wall of the small or large bowel • # Rare Secondary to coexis5ng disorders : 85% !  Intes5nal causes: ulcers, bowel obstrucJon, tumor, intesJnal •  40-50 years, male sexe ra5o parasites, inflammatory bowel disease, enteriJs, coeliac disease , mesenteric ischemia, jejunoileal bypass… !  Pulmonary: asthma, cysJc fibrosis, chronic obstrucJve pulmonary disease… !  Medica5ons : corJcosteroids, chemotherapeuJc agents, lactulose… !  Systemic disease : scleroderma, Lupus

Bowel wall

Mesenteric vessels

Mesentery

!  Permeability of the mesenteric vessels !  Existence or not of a vascular supply

Dilata2on of the bowel lumen

Defect in SMA

SMA

Sag MIP

Coronal MIP

PaJent with occlusion of the superior mesenteric artery

Bowel wall

Mesenteric vessels

Mesentery

Dilata2on of the bowel lumen

!  Mesenteric vein gas +/- portal vein gas Mesenteric vein gas + pneumatosis intesJnalis = transmural necrosis in 91%* * Kernagis et all. Pneumatosis intesJnalis in paJents with ischemia: correlaJon of CT findings with viability of the bowel. AJR 2003;180:733—6.

Portal vein gas

Linear PI

Mesenteric veins gas Mesenteric vein gas Bubbly and linear PI Massive mesenteric ischemia

Bowel wall

Mesenteric vessels

Mesentery

Dilata2on of the bowel lumen

!  Mesentery infiltra2on = non specifc CT findins of acute bowel ischemia !  Dilata2on of the bowel lumen +/- luminal fluid - adynamic ileus - transmural lesion in case of irreversible ischaemia by loss of the tonus

Bowel distension with PI

Surgical causes of PMVG Mechanical obstruc5on ! Obstruc2ve tumor Le^ large bowel obstacle

Pneumatosis intes5nalis

Surgical causes of PMVG Aéropor5es chirurgicales Infec5ous causes = 15% Causes infec5euses !  Complicated diver2culi2s 2 most frequently reported cause of PMVG Abscess nd

Sep5c thrombophlebi5s of the inferior mesenteric vein (few days later)

Gas in the inferior mesenteric vein

Surgical causes of PMVG Infec5ous causes = 15% !  Abdominal abcess !  Cholecys22s and cholangi2s !  Acute appendici2s !  Severe pancrea22s !  Coli2s (inflammatory, pseudomembranous, candida infec5on in HIV) !  Abdominal tuberculosis

Surgical causes of PMVG Infec5ous causes = 15% Gastric necrosis with pneumatosis and portal vein gas in a context of necroJzing pancreaJJs Portal vein gas

Hypodensity in the uncinate process of the pancreas

Gastric distension with mural pneumatosis and no contrast enhancement

• 

Surgical causes of PMVG Others causes Advanced diges5ve cancers (gastric, colon)

•  Gastric ulcer •  Inges5on of caus5cs •  Blunt trauma 1% of cases Mecanism = increased intraluminal pressure causes wall alteraJon and allows gas to enter submucosal vein and flow to the portal vein

Surgical causes of PMVG Others causes Diges5ve tumor Portal vein gas

Caecal tumor with PI

Mesenteric vein gas

• 

Benign causes of PMVG Most o^en asymptoma5c

•  Pathogenesis mechanism unknown in most of the cases •  Medical conserva5ve management

Benign causes of PMVG !  Following endoscopic retrograde cholangiopancreatography !  Following gastric biopsy or sclerotherapy for esophageal varices, gastrostomy !  Following colonoscopy !  Jejunal feeding tube !  Pulmonary desease : asthma, emphysema !  Chemotherapy !  Liver transplanta2on

Benign causes of PMVG Massive PMVG with bowel distension and pneumatosis * following post opera5ve jejunal feeding tube

*

* *

* Jejunal finding tube

*

*

• 

TAKE HOME MESSAGE A radiologic finding of PMVG does not necessarily indicate a severe underlying pathology like acute mesenteric ischemia.

•  It can be seen in rela5vely benign situa5ons which only necessitate conserva5ve therapy. •  Tradi5onally, PMVG was considered as being an indicator of bad prognosis and as being associated with a par5cularly high mortality rate. •  With the increased u5liza5on of CT imaging, PMVG is being iden5fied more frequently and can pose difficult surgical dilemma. •  It is important to dis5nguish pa5ents with PMVG that require urgent interven5on from those with benign cause.

Management algorithm for PMVG iden5fied on CT scan* *Wayne E. and all, Management algorithm for pneumatosis intes5nalis and portal veinous gas. J Gastrointest Surg 2010

STEP 1

Yes

1. pa5ent cri2cally ill and unstable No

STEP 2

Does the pa5ent have 1. Any mechanical disease? 2. Any iatrogenic gastrointes2nal trauma within past 48 hours? No





Yes

ACempt to stabilize +/- surgical interven5on

Conserva5ve treatment or Surgical principles to treat specific cause

Strongly suspect mesenteric ischemia Exploratory laparotomy

STEP 3

Extremes ages Cardiovascular risk factors Abdominal pain+/-abnormal abdominal Lactates>=3 mg/dL Bowel pneumatosis

Possible mesenteric ischemia Minimally invasive strategies to assess bowel viability, rule out ischemia

Benign PMVG

ObservaJon with medical management