Transcript File

Bowel Ischemia
Dr. Ahmed Refaey
Consultant radiologist
Riyadh Military Hospital
Blood supply
Blood supply of small intestine

The entire small intestine
is supplied by the
superior mesenteric
artery and drain to the
superior mesenteric vein,
which in turn drains to
the portal vein.
The arterial supply of
the colon

That right part of the colon
to the midtransverse colon
is supplied by the superior
mesentric artery

The inferior mesenteric
artery supplies the colon
as far as the upper rectum
Venous drainage of the colon

Veins corresponding with arteries drain to
the superior and inferior mesenteric veins.
Blood supply of large intestine
Etiology
Risk factors
*
*
*
*
*
*
atrial fibrillation/flutter
recent acute myocardial infarction
hypovolemia or hypotension ( sepsis )
coagulation disorders or malignancy
portal hypertension/ cirrhosis
medications
- vasopressin-digitalis-beta blockers
Pathogenesis

Mesenteric arterial or venous narrowing or
occlusion leading to inadequate supply of
oxygen to the bowel.
Classification
Bowel ischemia
Acute or chronic
 Occlusive or nonocclusive
 Arterial or venous
 Small bowel or large bowel .
{{ ischemic enteritis or ischemic colitis }}.

Acute ischemia
Acute interruption of blood flow to the bowel
 causes :
@ arterial
_ occlusive
* embolism {40-50%} : atrial fibrillation or endocarditis
(SMA most commonly involved)
* thrombosis { 20-40% } : atherosclerosis
* mechanical obstruction: strangulation, tumor
_ nonocclusive
hypoperfusion ( low flow states, hypotension, sepsis or
heart failure with diffuse mesenteric vasoconstriction )
( IMA most commonly involved )
@ venous
* Mesenteric venous thrombosis { 10% }

.
Arterial sources occur more frequently than
venous sources by a ratio of 9:1
 Similarly, arterial occlusive disease occur more
frequently than nonocclusive disease by a ratio
of 9:1
 Large or smaller segments of bowel may be
involved, depending on the location of the
occlusion
 Regardless the mechanism, the disease follows
the same course.

.

Clinical details :
* clinical triad of {sudden onset of
abdominal pain, diarrhea & vomiting}
* diffuse abdominal pain, out of
proportion to physical examination.
* leukocytosis
* gross rectal bleeding

Chronic ischemia..
{ abdominal angina}
* * most commonly caused by
atherosclerosis of coeliac and SMAs &
symptoms are unlikely unless at least two
vessels are involved.
.
** clinical details
* post-prandial abdominal pain, 15-20 minutes
after food intake ( due to “gastric steal”
diverting blood flow away from intestine ) and
the pain subsides 1-2 hours after meal.
* fear of eating large meals
* malabsorption
* weight loss
Pathophysiology of bowel
ischemia
Mucosa is most sensitive area to anoxia from
arterial / venous occlusion with early ulceration,
later on necrosis and perforation occur.( of
clinical importance )
 Ischemia causes increased permeability of
capillaries resulting in both submucosal edema
and hemorrhage.( of radiological importance )

Ischemic colitis
Most cases are thought to be related to diminished blood
flow within the bowel
 Predominantly a disease involving the distribution of IMA
.i.e., from distal transverse colon to rectum
 When the more proximal colon is involved, it is
frequently associated with extensive small bowel
ischemia & a correspondingly much graver prognosis.
 Patients are usually elderly .
 The clinical picture may mimic acute diverticulitis.
 Most common cause of colitis in elderly & is often self
limiting.

.

Prognosis of ischemic colitis
1.
complete resolution (75%) within 1-3
months
Stricturing ischemia (20%)
Gangrenous with necrosis and
perforation (5%)
2.
3.
Imaging
Imaging
Plain abdominal radiography
 Barium study
 Angiography
 CT

Imaging

Plain abdominal radiograph
* abnormal in 20-40%
* thumbprinting ( non specific finding,
indicating intestinal wall edema with
haemorrhage
* pneumatosis
* PV gas
* pneumoperitoneum
( all indicative of bowel infarction)
SMA
thrombosis
.

81 y old woman
with myocardial
infarction. Plain
abdominal
radiograph
shows air in the
wall of right
colon and small
& large bowel
dilatation.
Barium study
Barium study
* small bowel
1 - thick, smooth valvulae
conniventes.
2 - Barium trapped
between the thick folds
produces the “ interspace
spicking”
3 – (1:2) cm submucosal
fluid or blood collections
can form, known as “
thumbprinting”
Thick, smooth
valvula
connivents
(black arrows)
 Interspace
spicking (white
arrows)
 Thumbprinting
(arrow head)

.
.
.
*
large bowel
1- thumbprinting
(75%)
2- ulceration
3- loss of
interhaustral folds
4- luminal narrowing
5- confined to left
hemicolon (90%)
.

Segmental narrowing
of the entire
transverse colon .
Within the narrowed
segment, there are
multiple
thumbprinting
indentations
.

Postischemic stricture
, contain
pseudodiverticula
CT
CT
Examination of choice
 Sensitivity more than 95% ( MDCT )
 Identifies or excludes other pathologies
 Delineates cause,severity and complications.
 Guides management

Acute ischemia, why CT ?
Plain film– 33% sensitivity – non specific –
no information on causes, severity.
 Barium study – do NOT do , non-specific,
interfere with CT
 Angiography – technically difficult,
invasive, contraindicated in hypotensive
patients

CT technique
MDCT “if possible”
 Water oral contrast {1000 cc}
“ not positive OC “
 IV contrast : 3-5 ml/sec
 Arterial and PV phase

.
CT findings
Suggestive signs
highly suggestive
signs
reliable signs
CT findings
•
Suggestive signs
1* “double halo” or “ target” sign. ( edema of
the submucosa –low attinuation- with
brighter mucosal and serosal surfaces in CECT )
2* circumferential bowel wall thickening
3* focal / diffuse bowel dilatation
4* increased attinuation of mesenteric fat ( edema )
5* pneumatosis intestinalis
6* pneumoperitoneum
7* ascites
8* variable enhancement pattern
.

highly suggestive
signs:
1- bowel wall
thickening with
dilatation
.
•
reliable signs:
1- thromboembolism in
mesenteric vessels.
2- lack of enhancement of
the ischemic segment of
bowel.
3- Portal venous & mural
gas.
.

A reliable method to differentiate arterial
causes from venous causes is depiction of
the characteristic bowel wall enhancement
pattern. Arterial occlusive disease
demonstrate no enhancement of the
involved segment, whereas venous
occlusive disease or hypoperfusion reveal
marked contrast enhancement and
retention 2ry to stagnant flow, with
thickening of bowel wall.
.
Differential diagnosis
* Causes of intramural edema ( hypoprotinemia, lymphatic
blockage 2ry to tumor, inflammatory infiltrate like graft
vs host disease and esinophilic enteritis.
 Inflammatory bowel disease (Crohn disease-UC)
 Infectious bowel diseases
 Causes of intramural hemorrhage:
1-ischemia
2-radiation
3-vasculitis –CT disease( SLE, RA,HenochSchonlein purpura)
4-bleeding : from hemophilia, thrombocytopenic purpura,
anticoagulant therapy, DIC.
.

SBFT shows “stack of
coins” small bowel
fold pattern due to
ischemia,intramural
hge.
.

Axial CECT in 23 y old
woman with
hypercoagulable state
+ bowel ischemia.
Dilated fluid filled
small bowel +
thrombosis of SMV.
.

Axial CECT shows
dilates small bowel
with areas of wall
thickening (arrow).
Patient has severe
abdominal pain.
Bowel infarction from
atrial fibrillation.

. , grossly thickened wall of
Patient with acute ischemia
the splenic flexure and descending colon. There is
intraperitoneal air in the subhepatic region &
Morrison’s pouch.

.
CT demonstrate distension of the caecum. The bowel wall is
thickened, and contains multiple small intramural gas bubbles.
.

CT scan shows
thickening of the
transverse colon .
These findings
suggest a distribution
in superior mesenteric
artery territory.
.

CT confirms the
presence of air in the
portal venous system
and proximal small
bowel mucosal
edema. These
findings suggest
ischemia of the
affected bowel.
Top CT image shows
gas in the portal
venous system (blue
circle).
 Center image shows
thrombosed SMA
(blue arrow) .
 Lower cuts show
extensive
pneumatosis
intestinalis.

.
SMV thrombosis
Ischemic colitis

The enema confirms
the appearance of
mucosal thickening
and localizes the
affected bowel to
distal transverse colon
, splenic flexure and
proximal descending
colon
Ischemic colitis

The enema confirms
the appearance of
mucosal thickening
and localizes the
affected bowel to
distal transverse colon
, splenic flexure and
proximal descending
colon.
.

Pneumatosis coli
.
Splenic flexure to
descending colon
watershed
 Ischemic colitis

.
Abscent
enhancement
 IMA occlusion
{left colic bransh}

.

SMA embolus
.

SMV thrombosis
Ischemic colitis

CT image in 22 y old
woman with ischemic
colitis after blunt
abdominal trauma to
right flank demonestrate
marked thickening of
hepatic flexure and right
colon, with abrupt
transition (arrows)
between abnormal and
normal wall in the
transverse colon.
.





Diffuse wall thickening of
all colon.
50 y old male
Diarrhea, abdominal pain,
fever, leukocytosis
Antibiotic (cephalosporin)
treatment since 2 weeks
Pseudomembranous
colitis
.






Marked low attinuation caecal
wall thickening as well as
proximal transverse colon with
moderate pericolonic
inflammatory stranding
45 y old male
Bloody diarrhea/ abdominal
pain/ fever/vomiting.
History of leukemia
Neutropenia
Typhlitis ( neutropenic colitis)
.





18 y old female
Small bowel wall
thickening ( not
dilated)
Mesenteric
inflammatory
stranding
Mesenteric
adenopathy
Crohn’s disease
.
15 y old boy
 Circumferential wall
thickening of
ascending colon
 Pericolic inflammatory
mesenteric fat
stranding
 Crohn’s disease

.
Axial CECT shows
narrowed lumen and
thickened wall of
descending colon .
Submucosal halo of
low density (edema)
and engorged blood
vessels indicate active
disease.
 Ulcerative colitis

.
Axial CECT shows
mural thickening of
ascending + transvrse
colon plus dilated
mesenteric vessels.
 Infectious colitis (
campylobacter colitis)

.
Diffuse colonic wall
thickness
 Antibiotic treatment
since 10 days
 Pseudomembranous
colitis

.
Thumbprinting of
transverse colon
 Ulcerative colitis

.
Pancolitis
 Diffuse wall
thickening of all colon
 Pseudomembranous
colitis.

Complications
Sepsis
 Septic shock
 Multiple system organ failure
 death

Mortality
.
Occlusive mesenteric infarction { embolus
or thrombosis } has a 90% mortality rate ,
whereas non-occlusive disease has a 10%
mortality rate .
 Ischemic enteritis----- 90% mortality rate
 Ischemic colitis-------- 10% mortality rate

Conclusion
.

The diagnosis of mesenteric ischemia often is a
challenge to both clinicians and radiologists .
Patients with inflammatory bowel disease and
infectious colitis can present with similar physical
signs and symptoms, including cramping
abdominal pain ,bloody diarrhea & leukocytosis.

Bowel wall thickening is a finding common to all
3 types of disease, however,the pattern of
vascular distribution can sometime narrow the
differential diagnosis.
.
Ischemic bowel disease is a clinicoradiological diagnosis
 High clinical suspecion is key to early
diagnosis
 Prognosis depends on underlying cause
not imaging.


•
•
•
•
•
Many classifications for bowel ischemia
{ arterial or venous}
{ occlusive or nonocclusive}
{ small or large bowel}
{ acute or chronic}
Regardless the mechanism, the disease follows
the same course.
Clinical picture is very important
Vascular supply is important ( location predicts
distribution)
CT findings are important { highly suggestive &
reliable}
DD: inflammatory & infectious bowel diseasesdiseases causing submucosal hge and edema.