Transcript Lower GI Bleeding

Lower GI Bleeding
Dr. Thamer
• LGI Bleeding :
– Abnormal hemorrhage into the lumen of the
bowel from a source distal to the ligament of
Treitz.
– 95% from the colon .
– Up to 40% of patients with lower GI bleeding,
more than one potential source of hemorrhage is
identified.
• Overt GI bleeding the presence of hematemesis,
melena, or hematochezia.
• Occult GI the absence of overt bleeding and is
identified on laboratory tests (e.g., irondeficiency anemia) or examination of the stool
(e.g., positive guaiac test).
• Obscure GI bleeding no source has been
identified by routine endoscopic studies (EGD and
colonoscopy).
• Obscure GI bleeding is occult in 20% of cases.
• The basic components of management are
1. initial hemodynamic stabilization,
2. Localization of the bleeding site, and
3. Site-specific therapeutic intervention.
Initial Evaluation and Resuscitation
• Two large-bore peripheral IV catheters should
be inserted and isotonic I.V. fluid
administered.
• A Foley catheter should be placed to facilitate
monitoring of intravascular volume status.
• Whether and in what form to administer
blood products is determined on an individual
basis, with appropriate weight given to the
presence or absence of comorbid conditions,
the rate of blood loss, and the degree of
hemodynamic stability.
• ICU monitoring in pt with HD instability .
• Focused Hx and physical Ex , to be carried out
simultaneously with resuscitation.
– nature and duration of bleeding, associated
symptoms, past medical history, complicating
comorbid conditions, medications
– postural vital signs, complete abdominal exam.
– laboratory tests (CBC, serum electrolytes,
coagulation profile, and typing and cross
matching).
• Place NG tube for gastric lavage.
• If lavage yields positive results (i.e., the aspirate
contains gross blood or coffee grounds),UGI scope.
• An aspirate that contains copious amounts of
bile is strongly suggestive of a lower GI source.
• The choice is less clear-cut with a clear
aspirate.
• In the absence of bile, such an aspirate cannot
rule out a duodenal source for the bleeding.
So , depending on the overall clinical picture, the
surgeon may choose either to perform EGD to
rule out a duodenal bleeding source or to
proceed with colonoscopy on the assumption
that the source of the bleeding is in the lower GI
tract.
Investigative Studies
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colonoscopy ,
radionuclide scanning,
CT scan, and
angiography (in the form of selective
mesenteric arteriography).
– The goal of these tests is to locate the site of
bleeding accurately so that definitive therapy can
be properly directed.
• Which diagnostic test is chosen for a specific
patient depends on several factors, including
– the hemodynamic stability of the patient,
– the bleeding rate,
– the comorbid conditions present, and
– the local expertise available at the physician’s
hospital.
Colonoscopy
• Most appropriate in the setting of minimal to
moderate bleeding
• Major hemorrhage interferes significantly with
visualization, and the diagnostic yield is low.
– In addition, the unstable patient, sedation and
manipulation may be associated with additional
complications and can interfere with resuscitation.
• Although the blood is cathartic, gentle
preparation with polyethylene glycol, either orally
or through an NG tube, can improve visualization.
• If the entire colon has been adequately
visualized and no source for the bleeding has
been identified, the ileum should be
intubated; fresh blood in this region suggests
a possible small bowel source.
– although this can be misleading because of
retrograde peristalsis in the colon.
• Overall diagnostic yields ranging from 53% to
97%.
• An average complication rate of 0.5%.
• Colonoscopy has both a higher diagnostic
yield and a lower complication rate than
arteriography in this setting and thus would
appear to be a more attractive initial test in
most circumstances.
• If no active bleeding is observed in the ileum,
upper GI endoscopy should be performed to
rule out an upper GI bleeding site.
• When colonoscopy and routine upper GI
endoscopy fail to locate a bleeding source,
push enteroscopy may be helpful.
• It can be performed purely endoscopically
with a pediatric colonoscope .
• In the OR during exploratory laparotomy.
• The surgeon can manually “milk” the small
bowel over the scope to evaluate its distal
portion or through an enterotomy and the
scope can be passed in both a retrograde and
an antegrade fashion .
Radionuclide Scanning
• Two imaging tracers, both labeled with
technetium-99m (99mTc), are currently
available for radionuclide scanning in this
setting:
– 99mTc-labeled sulfur colloid (99mTc-SC) and
– 99mTc-labeled red blood cells (RBCs).
• 99mTc-SC
– requires no preparation time and can be injected
immediately into the patient;
– Its rapid absorption into the liver and the spleen
can often hinder accurate localization of overlying
bleeding sites.
•
• 99mTc-labeled RBCs.
– Requires some preparation time,
– Longer half-life than 99mTc-SC does,
– Not taken up by the liver and spleen, and
– It can be detected on images as long as 24 to 48
hours after injection .
• 99mTc-labeled RBCs is the most sensitive but
least accurate method for localization of GI
bleeding.
• The patient's own RBCs are labeled and re
injected.
• The labeled blood is extravasated into the GI
tract lumen, creating a focus that can be
detected scintigraphically.
• Initially, images are collected frequently and
then at 4 hour intervals for up to 24 hours.
• The tagged RBC scan can detect bleeding as
slow as 0.1 mL/min and is reported to be
more than 90% sensitivity.
• Accuracy of localization is in the range of only
40% to 60%, and it is particularly inaccurate in
distinguishing right- from left-sided colonic
bleeding.
• The RBC scan is not usually employed as a
definitive study before surgery but instead as
a guide to the utility of angiography;
– if the RBC scan is negative or only positive after
several hours, angiography is unlikely to be
revealing.
• Such an approach avoids the significant
morbidity of the angiogram.
COMPUTED TOMOGRAPHY
• CT scanners were able to detect arterial bleeding
at rates as low as 0.07 ml/min, which suggests
that CT scanning is more sensitive than
angiography for this purpose.
• In addition, CT scans are noninvasive and carry
little morbidity.
• Unfortunately, like radionuclide scanning, CT has
no therapeutic capability & the use of CT in this
setting is the excessive dye load if angiography is
employed as well.
Mesenteric Angiography
• Can detect hemorrhage in the range of 0.5 to
1.0 mL/min and is generally only employed in
the diagnosis of ongoing hemorrhage.
• It can be particularly useful in identifying the
vascular patterns of angiodysplasias or
localizing actively bleeding diverticula.
• It has therapeutic capability .
• Catheter-directed vasopressin infusion can
provide temporary control of bleeding,
permitting hemodynamic stabilization .
• It can also be employed for embolization.
• Infusion of vasopressin is initiated at a rate of 0.2
U/min and can be increased to a rate of 0.4 U/min.
• Within 20 to 30 minutes, another angiogram is
performed to determine whether the bleeding has
ceased.
– If the bleeding is under control, the catheter is left in place
and vasopressin is continuously infused for 6 to 12 hours.
– If the bleeding continues to be controlled, infusion is
continued for an additional 6 to 12 hours at 50% of the
previous rate.
– Finally, vasopressin infusion is replaced by continuous
saline infusion, and if bleeding does not recur, the catheter
is removed.
• Systemic side effects, including myocardial
ischemia, peripheral ischemia, hypertension,
dysrhythmias, mesenteric thrombosis,
intestinal infarction, and death.
• Occasionally, simultaneous I.V. administration
of nitroglycerin is necessary to counteract
these systemic effects.
• The reported success rate of vasopressin in
controlling lower GI bleeding ranges from 60%
to 100%, and the incidence of major
complications ranges from 10% to 20%.
• 50% of patients experience re bleeding when
the medication is discontinued.
• Typically, such therapy is reserved for patients
whose underlying condition precludes surgical
therapy.
• Unfortunately, angiography is associated with
a significant risk for complications, including
hematomas, arterial thrombosis, contrast
reactions, and acute renal failure.
• An alternative for patients with coronary vascular
disease, severe peripheral vascular disease, or
other comorbidities that prevent safe
administration of vasopressin is transcatheter
embolization.
• In this technique, a catheter is superselectively
placed into the identified bleeding vessel and an
embolizing agent (e.g., a gelatin sponge, a
microcoil, polyvinyl alcohol particles, or a
balloon) is injected.
Operative Therapy
• Surgical intervention should be considered a
last resort in patients with LGIB.
• It is reserved for patients with
– persistent hemodynamic instability despite
aggressive resuscitation,
– the need for four or more blood transfusions in 24
hours or 10 units overall, or
– in the setting of recurrent severe bleeding.
• Operative intervention during the same
hospitalization in these situations is associated
with a better long-term outcome.
• Surgical evaluation may entail exploratory
laparotomy alone or combined with
intraoperative enteroscopy to evaluate the
small bowel, isolating a short segment at a
time.
• Operative management of LGIB has long been
a controversial subject.
• What is clear is that blind segmental resection
based on clinical suspicion alone has an
unacceptably high rate of rebleeding and
should not be performed.
• There is an emerging consensus that with
successful preoperative localization of
bleeding, segmental intestinal resection may
be considered with the understanding that it
bears a higher risk of rebleeding (0% to 14%)
than subtotal colectomy (0% to 4%).
• Subtotal colectomy, however, carries a higher
risk of intractable diarrhea.
• While LGIB resolves on its own in 80% of cases, it
recurs in 25% of cases.
• After a patient’s second major bleeding episode,
prophylactic resection is usually recommended
(assuming the site has been localized), because
the risk of rebleeding increases and exceeds 50%
after the second episode.
• Risk factors for rebleeding include severity of the
first bleed, major medical comorbidities, and the
need for anticoagulation.
• All patients require an open laparotomy with a
thorough examination of the entire intestine.
• Start with inspection , If the colon visually
appears filled with blood and the small
intestine remains spared, the surgeon must
still examine the entire abdomen and then
focus on colonic sources of bleeding.
• Exploration :
– The exploration begins in the stomach,
duodenum, and considers possible missed upper
gastrointestinal sources.
– Next, the small intestine must undergo
examination from the ligament of Treitz to the
ileocecal valve.
– Palpation of the intestine may demonstrate such
etiologies as a Meckel’s diverticulum, ileitis, colitis,
or a GIST.
• If no source appears obvious, the surgeon may
consider intestinal enteroscopy.
• The enteroscope or colonoscope will expose the
luminal surface and transilluminate the intestinal
wall for occult lesions.
• Transillumination may identify vascular
anomalies, small ulcers or tumors.
• Endoscopic access to the intestine may require
upper enteroscope, a transgastric approach, a
transcolonic approach, or insertion through the
anus .
• Once a hemorrhage site is identified, the
surgeon can perform an appropriate
segmental resection.
• If the source of bleeding cannot be found, and
it appears to arise from the colon, the surgeon
should perform a subtotal or total colectomy.
• Stable patients will tolerate a primary
ileosigmoid or ileorectal anastomosis in this
circumstance.
• Unstable patients require an end ileostomy
with closure of the rectal stump or a mucous
fistula.
• The rectum and sigmoid colon require
reexamination endoscopically to assure no
bleeding persists.
• Before the endoscopy, a simple saline
“washout” with a transanal catheter or via the
rigid proctosigmoidoscope may provide for
safe passage and careful examination of the
remaining mucosa.