Bowel IschemiaBowel Ischemia

Consultant radiologist Consultant radiologist Riyadh Military Riyadh Military HospitalHospital

Dr. Ahmed RefaeyDr. Ahmed Refaey

Blood supply Blood supply

Blood supply of small Blood supply of small intestineintestine

The entire small The entire small intestine is supplied intestine is supplied by the superior by the superior mesenteric artery and mesenteric artery and drain to the superior drain to the superior mesenteric vein, mesenteric vein, which in turn drains to which in turn drains to the portal vein.the portal vein.

The arterial supply The arterial supply of the colonof the colon

That right part of the That right part of the colon to the colon to the midtransverse colon is midtransverse colon is supplied by the supplied by the superior mesentric superior mesentric artery artery

The inferior mesenteric The inferior mesenteric artery supplies the artery supplies the colon as far as the colon as far as the upper rectumupper rectum

Venous drainage of the colonVenous drainage of the colon

Veins corresponding with arteries Veins corresponding with arteries drain to the superior and inferior drain to the superior and inferior mesenteric veins.mesenteric veins.

Blood supply of large intestineBlood supply of large intestine

Etiology Etiology

Risk factorsRisk factors

* atrial fibrillation/flutter* atrial fibrillation/flutter * recent acute myocardial infarction* recent acute myocardial infarction * hypovolemia or hypotension ( sepsis )* hypovolemia or hypotension ( sepsis ) * coagulation disorders or malignancy* coagulation disorders or malignancy * portal hypertension/ cirrhosis* portal hypertension/ cirrhosis * medications* medications - vasopressin-digitalis-beta blockers- vasopressin-digitalis-beta blockers

Pathogenesis Pathogenesis

Mesenteric arterial or venous Mesenteric arterial or venous narrowing or occlusion leading to narrowing or occlusion leading to inadequate supply of oxygen to the inadequate supply of oxygen to the bowel.bowel.

ClassificationClassification

Bowel ischemiaBowel ischemia

Acute or chronicAcute or chronicOcclusive or nonocclusiveOcclusive or nonocclusiveArterial or venousArterial or venousSmall bowel or large bowel .Small bowel or large bowel .

{{ ischemic enteritis or ischemic {{ ischemic enteritis or ischemic colitis }}.colitis }}.

Acute ischemiaAcute ischemia Acute interruption of blood flow to the bowel Acute interruption of blood flow to the bowel causes :causes : @ arterial@ arterial _ _ occlusiveocclusive * * embolism {40-50%} embolism {40-50%} : atrial fibrillation or : atrial fibrillation or

endocarditisendocarditis (SMA most commonly involved)(SMA most commonly involved) * thrombosis { 20-40% } * thrombosis { 20-40% } : atherosclerosis: atherosclerosis * mechanical obstruction* mechanical obstruction: strangulation, tumor: strangulation, tumor _ _ nonocclusive nonocclusive hypoperfusion hypoperfusion ( low flow states, hypotension, sepsis or ( low flow states, hypotension, sepsis or heart failure with diffuse mesenteric heart failure with diffuse mesenteric

vasoconstriction )vasoconstriction ) ( IMA most commonly involved )( IMA most commonly involved ) @ venous@ venous * Mesenteric venous thrombosis { 10% } * Mesenteric venous thrombosis { 10% }

..

Arterial sources occur more frequently Arterial sources occur more frequently than venous sources by a ratio of 9:1than venous sources by a ratio of 9:1

Similarly, arterial occlusive disease occur Similarly, arterial occlusive disease occur more frequently than nonocclusive disease more frequently than nonocclusive disease by a ratio of 9:1by a ratio of 9:1

Large or smaller segments of bowel may Large or smaller segments of bowel may be involved, depending on the location of be involved, depending on the location of the occlusionthe occlusion

Regardless the mechanism, the disease Regardless the mechanism, the disease follows the same course.follows the same course.

. . Clinical detailsClinical details : :

* clinical triad of {sudden onset * clinical triad of {sudden onset of abdominal pain, diarrhea & of abdominal pain, diarrhea & vomiting} vomiting}

* diffuse abdominal pain, out of * diffuse abdominal pain, out of proportion to physical examination. proportion to physical examination.

* leukocytosis* leukocytosis

* gross rectal bleeding* gross rectal bleeding

..Chronic ischemia. Chronic ischemia.

{ abdominal { abdominal angina}angina}

* * most commonly caused by * * most commonly caused by atherosclerosis of coeliac and SMAs atherosclerosis of coeliac and SMAs & symptoms are unlikely unless at & symptoms are unlikely unless at least two vessels are involved.least two vessels are involved.

. .

** clinical details** clinical details

* post-prandial abdominal pain, 15-20 * post-prandial abdominal pain, 15-20 minutes after food intake ( due to “gastric minutes after food intake ( due to “gastric steal” diverting blood flow away from steal” diverting blood flow away from intestine ) and the pain subsides 1-2 hours intestine ) and the pain subsides 1-2 hours after meal.after meal.

* fear of eating large meals* fear of eating large meals

* malabsorption* malabsorption

* weight loss* weight loss

Pathophysiology of bowel Pathophysiology of bowel ischemiaischemia

Mucosa is most sensitive area to anoxia Mucosa is most sensitive area to anoxia from arterial / venous occlusion with early from arterial / venous occlusion with early ulceration, later on necrosis and ulceration, later on necrosis and perforation occur.( of clinical importance )perforation occur.( of clinical importance )

Ischemia causes increased permeability of Ischemia causes increased permeability of capillaries resulting in both submucosal capillaries resulting in both submucosal edema and hemorrhage.( of radiological edema and hemorrhage.( of radiological importance )importance )

Ischemic colitisIschemic colitis

Most cases are thought to be related to Most cases are thought to be related to diminished blood flow within the boweldiminished blood flow within the bowel

Predominantly a disease involving the distribution Predominantly a disease involving the distribution of IMA .i.e., from distal transverse colon to rectumof IMA .i.e., from distal transverse colon to rectum

When the more proximal colon is involved, it is When the more proximal colon is involved, it is frequently associated with extensive small bowel frequently associated with extensive small bowel ischemia & a correspondingly much graver ischemia & a correspondingly much graver prognosis.prognosis.

Patients are usually elderly . Patients are usually elderly . The clinical picture may mimic acute diverticulitis.The clinical picture may mimic acute diverticulitis. Most common cause of colitis in elderly & is often Most common cause of colitis in elderly & is often

self limiting.self limiting.

..

Prognosis of ischemic colitisPrognosis of ischemic colitis

1.1. complete resolution (75%) within 1-complete resolution (75%) within 1-3 months3 months

2.2. Stricturing ischemia (20%)Stricturing ischemia (20%)

3.3. Gangrenous with necrosis and Gangrenous with necrosis and perforation (5%)perforation (5%)

ImagingImaging

ImagingImaging

Plain abdominal radiographyPlain abdominal radiographyBarium studyBarium studyAngiography Angiography CTCT

Imaging Imaging

Plain abdominal radiographPlain abdominal radiograph

* abnormal in 20-40%* abnormal in 20-40%

* thumbprinting ( non specific finding, * thumbprinting ( non specific finding, indicating intestinal wall edema with indicating intestinal wall edema with haemorrhagehaemorrhage

* pneumatosis* pneumatosis

* PV gas* PV gas

* pneumoperitoneum* pneumoperitoneum

( all indicative of bowel infarction) ( all indicative of bowel infarction)

SMA SMA thrombosisthrombosis

..

81 y old 81 y old woman with woman with myocardial myocardial infarction. Plain infarction. Plain abdominal abdominal radiograph radiograph shows air in the shows air in the wall of right wall of right colon and small colon and small & large bowel & large bowel dilatation.dilatation.

Barium studyBarium study

Barium study Barium study

* * small bowelsmall bowel1 - 1 - thick, smooth thick, smooth

valvulae conniventesvalvulae conniventes..

2 - Barium trapped 2 - Barium trapped between the thick between the thick folds produces the folds produces the “ “ interspace spicking”interspace spicking”

3 – (1:2) cm 3 – (1:2) cm submucosal fluid or submucosal fluid or blood collections can blood collections can form, known as “ form, known as “ thumbprinting”thumbprinting”

.. Thick, smooth Thick, smooth valvula valvula connivents connivents

((black arrowsblack arrows)) Interspace Interspace

spicking (spicking (white white arrowsarrows))

Thumbprinting Thumbprinting

((arrow headarrow head))

..

..

* * large bowellarge bowel 1- thumbprinting 1- thumbprinting

(75%)(75%)

2- ulceration2- ulceration

3- loss of 3- loss of interhaustral foldsinterhaustral folds

4- luminal 4- luminal narrowingnarrowing

5- confined to left 5- confined to left hemicolon (90%)hemicolon (90%)

..

Segmental Segmental narrowing of the narrowing of the entire transverse entire transverse colon . Within the colon . Within the narrowed segment, narrowed segment, there are multiple there are multiple thumbprinting thumbprinting indentationsindentations

..

Postischemic Postischemic stricture , contain stricture , contain pseudodiverticulapseudodiverticula

CTCT

CTCT

Examination of choiceExamination of choiceSensitivity more than 95% ( MDCT )Sensitivity more than 95% ( MDCT ) Identifies or excludes other pathologiesIdentifies or excludes other pathologiesDelineates cause,severity and Delineates cause,severity and

complications.complications.Guides managementGuides management

Acute ischemia, why CT ?Acute ischemia, why CT ?

Plain film– 33% sensitivity – non Plain film– 33% sensitivity – non specific –no information on causes, specific –no information on causes, severity.severity.

Barium study – do NOT do , non-Barium study – do NOT do , non-specific, interfere with CTspecific, interfere with CT

Angiography – technically difficult, Angiography – technically difficult, invasive, contraindicated in invasive, contraindicated in hypotensive patientshypotensive patients

CT techniqueCT technique

MDCT “if possible”MDCT “if possible”Water oral contrast {1000 cc} Water oral contrast {1000 cc}

“ not positive OC “ “ not positive OC “ IV contrast : 3-5 ml/secIV contrast : 3-5 ml/secArterial and PV phaseArterial and PV phase

..

CT findings

Suggestive signs highly suggestive

signs reliable signs

CT findings CT findings

• Suggestive signsSuggestive signs 1* “double halo” or “ target” sign. ( edema of 1* “double halo” or “ target” sign. ( edema of the submucosa –low attinuation- with the submucosa –low attinuation- with brighter mucosal and serosal surfaces in brighter mucosal and serosal surfaces in

CECT )CECT ) 2* circumferential bowel wall thickening2* circumferential bowel wall thickening 3* focal / diffuse bowel dilatation3* focal / diffuse bowel dilatation 4* increased attinuation of mesenteric fat 4* increased attinuation of mesenteric fat

( edema )( edema ) 5* pneumatosis intestinalis5* pneumatosis intestinalis 6* pneumoperitoneum6* pneumoperitoneum 7* ascites7* ascites 8* variable enhancement pattern 8* variable enhancement pattern

..

highly highly suggestivesuggestive signssigns: :

1- bowel wall 1- bowel wall thickening with thickening with dilatationdilatation

..

• reliablereliable signs: signs:

1- thromboembolism in 1- thromboembolism in mesenteric vessels. mesenteric vessels.

2- lack of enhancement 2- lack of enhancement of the ischemic of the ischemic segment of bowel.segment of bowel.

3- Portal venous & 3- Portal venous & mural gas.mural gas.

..

A reliable method to differentiate A reliable method to differentiate arterial causes from venous causes is arterial causes from venous causes is depiction of the characteristic bowel depiction of the characteristic bowel wall enhancement pattern. Arterial wall enhancement pattern. Arterial occlusive disease demonstrate no occlusive disease demonstrate no enhancement of the involved segment, enhancement of the involved segment, whereas venous occlusive disease or whereas venous occlusive disease or hypoperfusion reveal marked contrast hypoperfusion reveal marked contrast enhancement and retention 2ry to enhancement and retention 2ry to stagnant flow, with thickening of bowel stagnant flow, with thickening of bowel wall.wall.

..

Differential diagnosisDifferential diagnosis

* Causes of intramural edema ( hypoprotinemia, * Causes of intramural edema ( hypoprotinemia, lymphatic blockage 2ry to tumor, inflammatory lymphatic blockage 2ry to tumor, inflammatory infiltrate like graft vs host disease and esinophilic infiltrate like graft vs host disease and esinophilic enteritis.enteritis.

Inflammatory bowel disease (Crohn disease-UC)Inflammatory bowel disease (Crohn disease-UC) Infectious bowel diseasesInfectious bowel diseases Causes of intramural hemorrhage:Causes of intramural hemorrhage: 1-ischemia1-ischemia 2-radiation2-radiation 3-vasculitis –CT disease( SLE, RA,Henoch- 3-vasculitis –CT disease( SLE, RA,Henoch-

Schonlein purpura) Schonlein purpura) 4-bleeding : from hemophilia, thrombocytopenic 4-bleeding : from hemophilia, thrombocytopenic

purpura, anticoagulant therapy, DIC.purpura, anticoagulant therapy, DIC.

..

SBFT shows “stack SBFT shows “stack of coins” small of coins” small bowel fold pattern bowel fold pattern due to due to ischemia,intramuraischemia,intramural hge.l hge.

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Axial CECT in 23 y Axial CECT in 23 y old woman with old woman with hypercoagulable hypercoagulable state + bowel state + bowel ischemia. Dilated ischemia. Dilated fluid filled small fluid filled small bowel + bowel + thrombosis of SMV.thrombosis of SMV.

..

Axial CECT shows Axial CECT shows dilates small bowel dilates small bowel with areas of wall with areas of wall thickening (arrow). thickening (arrow). Patient has severe Patient has severe abdominal pain. abdominal pain. Bowel infarction Bowel infarction from atrial from atrial fibrillation.fibrillation.

.. Patient with acute ischemia , grossly thickened Patient with acute ischemia , grossly thickened wall of the splenic flexure and descending wall of the splenic flexure and descending colon. There is intraperitoneal air in the colon. There is intraperitoneal air in the subhepatic region & Morrison’s pouch.subhepatic region & Morrison’s pouch.

.. CT demonstrate distension of the caecum. The bowel wall is CT demonstrate distension of the caecum. The bowel wall is thickened, and contains multiple small intramural gas thickened, and contains multiple small intramural gas bubbles.bubbles.

..

CT scan shows CT scan shows thickening of the thickening of the transverse colon . transverse colon . These findings These findings suggest a suggest a distribution in distribution in superior superior mesenteric artery mesenteric artery territory.territory.

.. CT confirms the CT confirms the

presence of air in presence of air in the portal venous the portal venous system and system and proximal small proximal small bowel mucosal bowel mucosal edema. These edema. These findings suggest findings suggest ischemia of the ischemia of the affected bowel.affected bowel.

.. Top CT image Top CT image

shows gas in the shows gas in the portal venous portal venous system (blue circle).system (blue circle).

Center image shows Center image shows thrombosed SMA thrombosed SMA (blue arrow) .(blue arrow) .

Lower cuts show Lower cuts show extensive extensive pneumatosis pneumatosis intestinalis.intestinalis.

SMV thrombosisSMV thrombosis

Ischemic colitisIschemic colitis

The enema The enema confirms the confirms the appearance of appearance of mucosal thickening mucosal thickening and localizes the and localizes the affected bowel to affected bowel to distal transverse distal transverse colon , splenic colon , splenic flexure and flexure and proximal proximal descending colondescending colon

Ischemic colitisIschemic colitis

The enema The enema confirms the confirms the appearance of appearance of mucosal thickening mucosal thickening and localizes the and localizes the affected bowel to affected bowel to distal transverse distal transverse colon , splenic colon , splenic flexure and flexure and proximal proximal descending colon.descending colon.

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Pneumatosis coliPneumatosis coli

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Splenic flexure to Splenic flexure to descending colon descending colon watershedwatershed

Ischemic colitisIschemic colitis

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Abscent Abscent enhancementenhancement

IMA occlusion IMA occlusion {left colic {left colic bransh}bransh}

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SMA embolusSMA embolus

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SMV thrombosisSMV thrombosis

Ischemic colitisIschemic colitis

CT image in 22 y old CT image in 22 y old woman with ischemic woman with ischemic colitis after blunt colitis after blunt abdominal trauma to abdominal trauma to right flank right flank demonestrate marked demonestrate marked thickening of hepatic thickening of hepatic flexure and right colon, flexure and right colon, with abrupt transition with abrupt transition (arrows) between (arrows) between abnormal and normal abnormal and normal wall in the transverse wall in the transverse colon.colon.

..

Diffuse wall thickening Diffuse wall thickening of all colon.of all colon.

50 y old male50 y old male Diarrhea, abdominal Diarrhea, abdominal

pain, fever, pain, fever, leukocytosisleukocytosis

Antibiotic Antibiotic (cephalosporin) (cephalosporin) treatment since 2 treatment since 2 weeksweeks

Pseudomembranous Pseudomembranous colitiscolitis

.. Marked low attinuation Marked low attinuation

caecal wall thickening as caecal wall thickening as well as proximal transverse well as proximal transverse colon with moderate colon with moderate pericolonic inflammatory pericolonic inflammatory strandingstranding

45 y old male45 y old male Bloody diarrhea/ Bloody diarrhea/

abdominal pain/ abdominal pain/ fever/vomiting.fever/vomiting.

History of leukemiaHistory of leukemia NeutropeniaNeutropenia Typhlitis ( neutropenic Typhlitis ( neutropenic

colitis)colitis)

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18 y old female18 y old female Small bowel wall Small bowel wall

thickening ( not thickening ( not dilated)dilated)

Mesenteric Mesenteric inflammatory inflammatory strandingstranding

Mesenteric Mesenteric adenopathyadenopathy

Crohn’s diseaseCrohn’s disease

..

15 y old boy15 y old boy Circumferential Circumferential

wall thickening of wall thickening of ascending colonascending colon

Pericolic Pericolic inflammatory inflammatory mesenteric fat mesenteric fat strandingstranding

Crohn’s diseaseCrohn’s disease

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Axial CECT shows Axial CECT shows narrowed lumen narrowed lumen and thickened wall and thickened wall of descending colon of descending colon . Submucosal halo . Submucosal halo of low density of low density (edema) and (edema) and engorged blood engorged blood vessels indicate vessels indicate active disease.active disease.

Ulcerative colitisUlcerative colitis

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Axial CECT shows Axial CECT shows mural thickening of mural thickening of ascending + ascending + transvrse colon transvrse colon plus dilated plus dilated mesenteric mesenteric vessels.vessels.

Infectious colitis Infectious colitis ( campylobacter ( campylobacter colitis)colitis)

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Diffuse colonic wall Diffuse colonic wall thicknessthickness

Antibiotic Antibiotic treatment since 10 treatment since 10 daysdays

PseudomembranouPseudomembranous colitiss colitis

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Thumbprinting of Thumbprinting of transverse colontransverse colon

Ulcerative colitisUlcerative colitis

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PancolitisPancolitis Diffuse wall Diffuse wall

thickening of all thickening of all coloncolon

PseudomembranouPseudomembranous colitis.s colitis.

ComplicationsComplications

SepsisSepsisSeptic shockSeptic shockMultiple system organ failureMultiple system organ failuredeathdeath

Mortality Mortality

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Occlusive mesenteric infarction Occlusive mesenteric infarction { embolus or thrombosis } has a { embolus or thrombosis } has a 90% mortality rate , whereas non-90% mortality rate , whereas non-occlusive disease has a 10% occlusive disease has a 10% mortality rate .mortality rate .

Ischemic enteritis----- 90% mortality Ischemic enteritis----- 90% mortality raterate

Ischemic colitis-------- 10% mortality Ischemic colitis-------- 10% mortality raterate

ConclusionConclusion

.. The diagnosis of mesenteric ischemia The diagnosis of mesenteric ischemia

often is a challenge to both clinicians and often is a challenge to both clinicians and radiologists . Patients with inflammatory radiologists . Patients with inflammatory bowel disease and infectious colitis can bowel disease and infectious colitis can present with similar physical signs and present with similar physical signs and symptoms, including cramping abdominal symptoms, including cramping abdominal pain ,bloody diarrhea & leukocytosis.pain ,bloody diarrhea & leukocytosis.

Bowel wall thickening is a finding common Bowel wall thickening is a finding common to all 3 types of disease, however,the to all 3 types of disease, however,the pattern of vascular distribution can pattern of vascular distribution can sometime narrow the differential sometime narrow the differential diagnosis.diagnosis.

..

Ischemic bowel disease is a clinico-Ischemic bowel disease is a clinico-radiological diagnosisradiological diagnosis

High clinical suspecion is key to early High clinical suspecion is key to early diagnosisdiagnosis

Prognosis depends on underlying Prognosis depends on underlying cause not imaging.cause not imaging.

Many classifications for bowel ischemiaMany classifications for bowel ischemia { arterial or venous}{ arterial or venous} { occlusive or nonocclusive}{ occlusive or nonocclusive} { small or large bowel}{ small or large bowel} { acute or chronic}{ acute or chronic}• Regardless the mechanism, the disease Regardless the mechanism, the disease

follows the same course.follows the same course.• Clinical picture is very importantClinical picture is very important• Vascular supply is important ( location Vascular supply is important ( location

predicts distribution)predicts distribution)• CT findings are important { highly CT findings are important { highly

suggestive & reliable}suggestive & reliable}• DD: inflammatory & infectious bowel DD: inflammatory & infectious bowel

diseases- diseases causing submucosal hge diseases- diseases causing submucosal hge and edema.and edema.