Page 9 - Gastrointestinal Bleeding (Xuất huyết tiêu hóa)

CHAPTER 20 Gastrointestinal Bleeding 283

Hemostatic spray is a inorganic powder with clotting abilities
that can create a mechanical barrier that adheres to and covers a Surgery 20
bleeding site. 41-44 The technique can be used for temporary con- In selected patients with severe, ongoing GI bleeding in whom a
trol of bleeding from peptic ulcers, tumors, and diffusely bleeding diagnosis is not made by urgent endoscopy or colonoscopy, sur-
lesions; however, for patients with severe nonvariceal bleeding gical consultation is recommended. Patients who have massive
(such as from ulcers or Dieulafoy lesions [see later]) or varices hemorrhage and cannot be stabilized hemodynamically should
(esophageal or gastric), subsequent definitive hemostasis is usu- undergo emergency angiography or urgent surgical exploration
ally required with repeat endoscopy, angiography, or surgery. (either without prior endoscopy or with emergency endoscopy
performed in the operating room [see later]). Patients with bleed-
Imaging ing that cannot be controlled with endoscopy or angiography and
those with severe recurrent obscure GI bleeding may also benefit
Angiography may be used to diagnose and treat severe bleeding, from surgery with intraoperative enteroscopy (see later).
especially when the cause cannot be determined by upper and
lower endoscopy. Angiography is generally diagnostic of extrav- UPPER GASTROINTESTINAL BLEEDING
asation into the intestinal lumen only when the arterial bleeding
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rate is at least 0.5 mL/min. The sensitivity of mesenteric angi- Epidemiology
ography is 30% to 50% (with higher sensitivity rates for active
GI bleeding than for recurrent acute or chronic occult bleeding), Of the potential causes of severe UGI bleeding, peptic ulcer is
and the specificity is 100%. Angiography permits therapeutic the most common, accounting for approximately 40% of cases
46
intra-arterial infusion of vasopressin or transcatheter emboliza- (Table 20.2). 61,62 Despite advances in medical therapy, ICU care,
tion for hemostasis if active bleeding is detected, without the endoscopy, and surgery, the mortality rate of 5% to 10% for
need for bowel cleansing. The rate of major complications, severe UGI bleeding has not changed since the 1970s, 1,61-65 in
including hematoma formation, femoral artery thrombosis, part because of an increase in the proportion of older patients
contrast dye reactions, acute kidney injury, intestinal ischemia, with GI bleeding who die of severe comorbid conditions rather
and transient ischemic attacks, is 3%. Moreover, angiography than exsanguination, and an increase in the number of patients
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does not usually identify the specific cause of bleeding, only its with cirrhosis and variceal bleeding.
location. Bleeding is self-limited in 80% of patients with UGI hem-
Radionuclide imaging is occasionally helpful for patients with orrhage, even without specific therapy. 63,66 Of the remaining
unexplained GI bleeding, although it is used less frequently now 20% who continue to bleed or rebleed, the mortality rate is
8
than in the past because of the widespread use of endoscopy and 30% to 40%. Patients at high risk for continuous bleeding or
lack of availability of nuclear medicine services for emergencies, for rebleeding potentially benefit the most from acute medical,
particularly at night and on weekends. Radionuclide imaging can endoscopic, angiographic or surgical therapy.
be performed relatively quickly and may help localize the gen-
eral area of bleeding and thereby guide subsequent endoscopy, Risk Factors and Risk Stratification
angiography, or surgery. The technique involves IV injection
of a radiolabeled substance into the patient’s bloodstream, fol- Scoring tools have been developed to try to identify patients
lowed by serial scintigraphy to detect focal collections of radiola- with nonvariceal UGI bleeding at greatest risk for mortality and
beled material. Radionuclide imaging has been reported to detect rebleeding and to triage patients to a higher level of hospital care or
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bleeding at a rate of 0.04 mL/min. RBCs are generally labeled more urgent endoscopy. Pre-endoscopy scoring systems for non-
with technetium pertechnetate because they remain in the cir- variceal bleeding include the Blatchford Score, the Clinical Rockall
culation for up to 24 hours so that scanning can be repeated in Score, an artificial neural network score, and the AIMS65 score.
patients with either active or intermittent GI bleeding. 49 The Blatchford Score uses pre-endoscopy variables, including
The overall rate of a tagged RBC scan for the diagnosis of
hematochezia is low (<30%), and up to 25% of scans suggest a
site of bleeding that proves to be incorrect. 50-52 The rate of true- TABLE 20.2 Causes of Severe UGI Bleeding in the UCLA CURE
positive scans is higher when bleeding is active and associated Database (Nn = 968)
with hemodynamic instability than when bleeding is less severe. Cause Frequency (%)
53
The most common reason for a false-positive result is the rapid
transit of luminal blood, so that labeled blood is detected in the Peptic ulcer 35.2
colon even though it originated from a more proximal site in the Esophageal or gastric varix 21.9
GI tract. Caution is recommended in using the results of delayed Portal hypertension-related lesion* 4.6
scans to localize and target lesions for surgical resection. 54
Technetium pertechnetate scintigraphy can identify ectopic Esophagitis 4.6
gastric mucosa in a Meckel diverticulum. This diagnosis should Angioectasia † 4.0
be considered in a pediatric or young adult patient with unex- Mallory-Weiss tear 4.0
plained GI bleeding. The positive predictive value, negative pre-
dictive value, and overall accuracy of a so-called Meckel scan have Dieulafoy lesion 3.2
been reported to be higher than 90% in young patients. 55,56 In UGI tract neoplasm 3.1
patients older than 25 years of age, however, Meckel scans are Epistaxis 2.2
much less sensitive (<50%). 57
In patients with a prior abdominal aortic aneurysm repair and Erosions 1.2
graft, CT with IV contrast can identify inflammation between Other 8.8
the graft and duodenum and suggest graft fistulization into the No cause found 7.3
duodenum. In selected patients, abdominal CT can also identify
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a mass lesion, such as an intra-abdominal tumor, or small bowel *Other than an esophageal or gastric varix
†
Angioectasia and telangiectasia
abnormalities that may suggest a cause of bleeding. Advances in CURE, Center for Ulcer Research and Education; UCLA, University of
CT and MRI technology have permitted CT and MRI enterog- California, Los Angeles.
raphy and angiography, with promising results. 59,60