SEVERE ABDOMINAL PAIN
OUT OF PROPORTION TO
FINDINGS ON EXAMINATION …
THINK ABOUT
MESENTERIC ISCHEMIA
Sudden reduction in arterial perfusion of the
small bowel results in immediate central
abdominal pain
Progressive involvement of muscular layer
Serosa
Peritoneal signs
Acute mesenteric ischemia
Thrombotic
Embolic
Non-occlusive
Thrombotic
Due to an acute arterial thrombosis which
occludes the orifice of the superior
mesenteric artery (SMA), resulting in
massive ischemia of the entire small bowel
plus the right colon
Embolic
Due to a shower of embolic material originating
proximally – from the heart (AF, post MI,
diseased valve) or aneurysmal or atherosclerotic
aorta.
Emboli lodge at the proximal SMA, below the
entry of the middle colic artery, therefore the
most proximal segment of the jejunum is spared.
Emboli tend to fragment and re-emboli distally –
producing a patchy type of ischemia
Non-occlusive
Low flow state – no documented thrombosis or
emboli
Low cardiac output (cardiogenic shock), reduced
mesenteric flow (increased intra-abdominal
pressure) or mesenteric vasoconstriction
(administration of vasopressors)
Usually develops in the setting of pre-existent
critical illness
Mesenteric Venous Thrombosis
Can also produce small bowel ischemia
Clinical features and management
completely different from the above three
The problem – in clinical practice mesenteric
ischemia is usually recognized too late, after it
has led to intestinal gangrene, sepsis and organ
failure
Even if the patient survives - development of
short bowel syndrome
Therefore – early diagnosis and treatment are
crucial
Clinical picture
The early clinical picture is non-specific – severe
abdominal pains, minimal abdominal findings
Preceding symptoms – mesenteric angina (pain
with meals, weight loss)
History of IHD
Source of emboli
Low flow state in moribund patients due to
underlying critical disease
If peritonitis – usually signifies dead bowel
Abdominal x-rays in the early course of the
illness are normal. Later – adynamic ileus
Laboratory tests – initially normal. As
bowel ischemia progresses – leukocytosis,
hyperamylasemia, lactic acidosis
Therefore – high level of suspicion and
active search for the diagnosis in the early
phase to prevent bowel necrosis
Abdominal CT-Angio
Mesenteric Angiography
Contraindicated in the presence of acute
abdomen
Mesenteric Angiography
Invasive, takes time and requires experienced
personnel – only if CT-Angio non diagnostic and
there is still high probability of vascular event
To rule out non-occlusive disease
Advantage – can be therapeutic
Occluded ostium of SMA – Thrombosis,
immediate operation unless good collateral flow.
The angio provides road map for reconstruction.
In Emboli, the first few cm of SMA are patent
Non-operative Treatment
Only if no peritoneal signs, usually in emboli
Selective infusion of thrombolytic agent,
papaverine to relieve the associated mesenteric
vasospasm
Only cessation of abdominal symptoms and
angiographic resolution can be regarded as a
success
In non-occlusive mesenteric ischemia – attempt
to improve intestinal flow by restoring altered
hemodynamics. Selective intra-arterial infusion
of vasodilator.
In emboli – long term anti-coagulation
Operative Treatment
Peritoneal signs
Failure of non-operative regimen
Two possibilities :
Frank gangrene
Ischemia, questionable viability
Frank Gangrene
Gangrene of the entire small bowel and
right colon – signifies SMA thrombosis.
Total resection + TPN for life not practical
Shorter gangrene or multiple segments –
emboli. Excision of all dead bowel and
evaluation of the rest. Less than 1 meter of
small bowel will require in half of patients
TPN for life
Questionable viability
Possibility of embolectomy in emboli or vasculoar reconstruction –
only if bowel questionably viable.
Consider second-look operation if remaining questionable bowel too
long and massive resection required
Signs of viability – color, peristalsis, pulsation in mesenterium
Anastomosis – selectively. Stable patient, fair nutritional status,
remaining bowel unquestionably viable, no severe peritonitis.
Anastomosis after massive resection – intractable diarrhea
The main reason not to anastomose – the possibility that further
ischemia may develop
If anastomosis not safe – exteriorize both end of the bowel as endileostomy and mucous fistula for a later re-anastomosis
Second-look Operation
A planed re-operation – has to be decided
during the first operation
Allows to re-assess intestinal viability
Allows to preserve the greatest possible
length of viable intestine
Has to be done after 24-48 hours to
prevent SIRS
Mesenteric Vein Thrombosis
Occlusion of the venous outflow of the bowel.
Rare, may be idiopathic or secondary to
hypercoagulable state or sluggish portal flow
(cirrhosis)
Clinical presentation non-specific, may last
several days until the intestine is compromised
and peritoneal signs develop
CT may be diagnostic – intra-peritoneal fluid,
thickened segment of small bowel, thrombus in
the SMV
MVT - Treatment
If no peritoneal signs – full anticoagulation – may result
in spontaneous resolution and avoid surgery
Failure to improve on heparin or peritoneal signs
mandate an operation
At operation – the involved segment of small bowel is
thick, edematous, dark blue, arterial pulsation present,
thrombosed veins.
Resection of the involved segment, the same
considerations as for arterial ischemia regarding
anastomosis or second look.
Postoperative anticoagulation to prevent thrombus
progression