Chảy máu đường tiêu hóa chụp hóa chất đánh dấu ENG

EDUCATION PRACTICEObscure Gastrointestinal Bleeding: The Role of the Tagged Red Blood Cell Scan, Enteroscopy, and Capsule Endoscopy DAVID R.. What is the role of tagged red cell nuclear

Trang 1

EDUCATION PRACTICE

Obscure Gastrointestinal Bleeding: The Role of the Tagged Red Blood Cell Scan, Enteroscopy, and Capsule Endoscopy

DAVID R CAVE

Division of Gastroenterology, University of Massachusetts Medical Center, Worcester, Massachusetts

Clinical Scenario

A 65-year-old African American man was referred

for obscure gastrointestinal bleeding He initially had

presented 3 months previously with anemia and melena

Both upper-gastrointestinal endoscopy and colonoscopy

on 2 occasions had not shown a bleeding source A

tagged technetium-99m red blood cell bleeding scan was

negative He had no weight loss or abdominal pain He

had received a total of 25 units of blood Physical

exam-ination was unremarkable

How should this patient be evaluated? What is the

role of tagged red cell nuclear scans, capsule endoscopy,

angiography, and intraoperative endoscopy in patients

with obscure gastrointestinal bleeding?

The Problem

Obscure gastrointestinal bleeding, either occult

or overt, refers to gastrointestinal bleeding that persists

or recurs for which a source has not been defined by a

thorough upper-endoscopy and colonoscopy Figure 1

shows the constituent types of obscure bleeding Obscure

bleeding usually is considered to represent about 5% of

patients with gastrointestinal bleeding However, this

figure usually is based on loose definitions as to the

source, such as attributing gastric erosions or the

pres-ence of colonic diverticulosis as the bleeding source,

without direct visualization of active bleeding If a more

rigorous definition is used in which the bleeding source

is defined as one that is bleeding actively or has evidence

of stigmata of recent hemorrhage then up to 24% of

bleeds are considered to be of unknown origin Clearly

only a small portion of gastrointestinal bleeds will

be-come recurrent or persistent The wider availability of

capsule endoscopy has started to provide more accurate

data because we now can examine the entire length of the

small intestine noninvasively, albeit not the entire

mu-cosal surface The timing of endoscopy clearly is

impor-tant because 80% of acute gastrointestinal bleeding stops

spontaneously Aggressive colonoscopy clearly provides a

higher detection rate of active lower-gastrointestinal bleeding and capsule endoscopy has been shown to have

a very high yield in identifying a source of obscure bleeding with concurrent active bleeding

Management Strategies and Supporting Evidence

Management of obscure GI bleeding depends on a variety of factors, some patient-related and others related

to personnel and facilities When the patient presents for the first time with acute gastrointestinal bleeding it is not possible to predict whether or not they have obscure bleeding A careful history and physical examination does provide useful information and often can direct the most appropriate initial examination If the presenting complaint is hematemesis, upper endoscopy clearly is the diagnostic procedure of choice Similarly, bright red rectal bleeding or the passage of maroon stools usually is investigated initially by colonoscopy Patients presenting with melena provide more of a challenge because melena can originate all the way from the upper-gastrointestinal tract to the right side of the colon A frequent com-pounding variable is that it often is difficult to clarify whether or not the patient has passed red blood, maroon stool, melena, or a combination Although the use of color cards to identify stool color may be of some benefit,

it should be noted that stool color can vary from stool to stool in the same patient depending on the rapidity and source of bleeding

Bleeding scans are reported to be able to detect bleed-ing at the rate of 1–.5 mL/min Published data suggest scans are positive in 26%–72% of patients However, the study designs that established these data have consider-able limitations They generally do not include an ap-propriate denominator (ie, the total number of patients tested) and are reported selectively for severe bleeding

1542-3565/05/$30.00 PII: 10.1053/S1542-3565(05)00716-0

Trang 2

There are no studies that relate the accuracy of

techne-tium-99m red blood cell scans to obscure gastrointestinal

bleeding The accuracy for detecting bleeding in the

colon is quite good, particularly if the scan is positive

almost immediately after injection In the small

intes-tine, results of the red cell scans can be very misleading

because of rapid transit of the isotope in the small

intestine Not infrequently the isotope pools in the

ce-cum when bleeding has originated in the small intestine

Similar limitations with false localization of the bleeding

source may occur with late scanning, which may suggest

a bleeding source in the colon

Capsule endoscopy now is available widely for the

detection of obscure gastrointestinal bleeding and is

becoming the examination of choice in this context It is

noninvasive and generally does not require significant

bowel preparation It currently is used predominantly in

the outpatient setting in patients with a history of

ob-scure bleeding However, there is accumulating evidence

that the use of capsule endoscopy during or as close to the

active bleeding event as possible may show a bleeding

source in up to 92% of patients actively bleeding at the

time of video capsule endoscopy This suggests that

capsule endoscopy should be performed as early as

pos-sible, even during the night shortly after the patient has

been admitted and stabilized Such an approach may

minimize the chances of bleeding ceasing before testing

is initiated

The recent development of the double-balloon push

enteroscope now has increased greatly the diagnostic and

therapeutic capabilities of push enteroscopy However,

the technology is only available in a few centers and is

both capital- and labor-intensive The concept behind

this technology is that the alternating inflation and

deflation of balloons on the end of the endoscope and on

the end of an overtube, and the change in the relation-ship of the 2, allows for pleating and hence shortening of the small intestine over the endoscope, thereby minimiz-ing loop formation The complexities of this procedure suggest that capsule endoscopy and push enteroscopy should be performed before double-balloon enteroscopy, but the latter procedure does allow for nonsurgical in-tervention much further into the small bowel than pre-viously was possible without intraoperative enteroscopy Indeed, in some patients complete endoscopy of the small bowel has been reported either by the oral route or

by the combination of oral and anal approaches

A therapeutic version of the double-balloon scope recently has become available and is fitted with a 2.8-mm channel This allows cauterization of vascular or bleeding lesions with bipolar or argon plasma coagula-tion, biopsy examination of tumors, and the snaring of polyps in the small intestine The injection of India ink may be used to tattoo the point of maximal insertion so that when the ileum is intubated retrograde at the time

of colonoscopy the mark can be used to confirm visual-ization of the entire small intestine Obviously, if the bleeding site, which may include angioectasia, tumors, and ulcers, are within range of a standard push entero-scope, then the full range of diagnostic and therapeutic procedures are available to the clinician Intraoperative enteroscopy remains the gold standard for the detection

of small intestinal bleeding An appropriate endoscope, such as an enteroscope, can be inserted via the mouth or via an enterotomy and passed along the small intestine to help the surgeon localize the source of bleeding This often is traumatic to the small-bowel mucosa and is by

no means 100% effective Laparoscopy-assisted intraop-erative endoscopy is still in the experimental phase

Areas of Uncertainty

There is a clear need to define and validate a cost-effective and clinically appropriate algorithm for evaluating patients with obscure gastrointestinal bleeding

Should Endoscopy Be Repeated?

Repeating upper-gastrointestinal endoscopy and colonoscopy when previous studies have been negative is still frequently performed for the diagnosis of obscure gastrointestinal bleeding, but the yield is low It prob-ably is not necessary to repeat these procedures if careful and complete examinations have been performed recently

by a skilled endoscopist However, the aggressive use of colonoscopy with the initiation of bowel preparation as soon as the patient has been admitted to the emergency room has been reported to increase the diagnostic yield

Figure 1 Definitions of obscure gastrointestinal bleeding FOBT,

fe-cal occult blood testing; IDA, iron-deficiency anemia.

Trang 3

and therapeutic opportunity for patients with colonic

bleeding

Capsule Endoscopy or Push

Enteroscopy?

Assuming that the presenting patient has had at

least one careful upper endoscopy and colonoscopy and

they present for the second time with evidence of blood

loss, the choice of the next test ideally should be limited

to either capsule endoscopy or push enteroscopy Some

investigators have preferred to use push enteroscopy

be-fore capsule endoscopy because therapy can be

under-taken during the procedure This is not a current option

with capsule endoscopy The choice of procedures

de-pends on the availability of each technology, the skill of

the local endoscopist, and the presentation of the

indi-vidual patient The diagnostic yield of push enteroscopy

for obscure gastrointestinal bleeding ranges from 38% to

75% However, in the studies comparing push

enteros-copy with capsule endosenteros-copy, the yield was considerably

lower Sonde enteroscopy now largely has been

aban-doned and the use of surgical intervention and

intraop-erative enteroscopy now largely is determined by the

results of capsule endoscopy The most common sources

of bleeding, as detected by capsule endoscopy, are listed

inTable 1

Use of Red Blood Cell Tagged

Scans Before Angiography

If the patient is unstable hemodynamically and

thought to have a lower-gastrointestinal bleed, a gamma

camera bleeding scan possibly followed by angiography

is a frequently used strategy However, this does require

considerable resources and is difficult to organize partic-ularly outside normal working hours The majority of radiology departments require a bleeding scan be per-formed before the use of angiography In practice there are many occasions when the time taken for the perfor-mance of the bleeding scan is associated with cessation of bleeding by the time angiography is performed and the opportunity for detection of the source of bleeding is lost Angiography rarely is indicated and it is restricted

to patients with severe hemorrhage Angiography re-quires at least 5 mL of blood loss per minute for the detection of extravasated contrast material Pharmaco-logic stress testing with the local infusion of heparin, tissue plasminogen activator, and a vascular dilating agent into mesenteric vessels has been reported with a yield of provoking bleeding in about 30% of patients

No adverse events were reported Obviously, any bleed-ing that is provoked potentially can be controlled by embolic techniques

Is the Visualized Lesion the Source

of Bleeding?

In the absence of bleeding, the endoscopist has to make a decision as to whether the presence of an erosion, ulcer, angioectasia, or tumor may be the actual source of

bleeding This may be referred to as endoscopic

rational-ization An example of this dilemma was a patient with

melena who on endoscopic examination had a small gastric ulcer without stigmata of recent hemorrhage, 2 large polypoid masses on colonoscopy, 1 carcinoma of the cecum, and a 4-cm polyp in the sigmoid On capsule endoscopy, active bleeding was found to be originating

in the small intestine The colonic or gastric lesion could have been rationalized as the source of bleeding if the capsule endoscopy had not been performed This type of rationalization is carried to the extreme in the colon, where the conventional colonoscopic work-up of acute lower-gastrointestinal bleeding often shows no active bleeding The presence of diverticulosis usually is re-garded as the origin of the bleeding in the absence of other overt pathology

Published Guidelines

The American Gastroenterological Association published a technical review in 2000 based on the eval-uation and management of occult and obscure gastric intestinal bleeding based on a review of data published in

1998 or earlier This review contained an extensive anal-ysis of the evaluation of occult bleeding and of obscure bleeding Etiology, diagnostic techniques, management, and outcomes were reviewed in detail, but

recommenda-Table 1 Most Common Causes of Obscure Gastrointestinal

Bleeding

Negative findings 38

Positive findings

Aphthoid ulcers ⫹ serpiginous ulcers 5

Ulcers ⫹/⫺ stenosis 6

Suspicious findings

Isolated angioectasia 8

Gastric lesions

Gastric antral venous ectasia 1

Data from Pennazio et al 4

Trang 4

tions were not specified, either descriptively or by

algo-rithm This review also predated the introduction of

capsule endoscopy and double-balloon enteroscopy by

several years The development of these 2 techniques

requires us to reconsider our approach to diagnose

ob-scure gastrointestinal bleeding

Recommendations

Figure 2 shows a practical view of the

manage-ment of obscure gastrointestinal bleeding and it also

applies to the evaluation of both iron-deficiency anemia

and overt obscure gastrointestinal bleeding This

algo-rithm is an update to one published earlier It should be

noted that conventional barium radiology, specifically a

small-bowel series and enteroclysis, are not included in

the algorithm because extensive data have shown that

their application in the context of obscure bleeding is of

minimal benefit The algorithm does not include the

initial evaluation and stabilization of the patient, which

are part of routine care The severity of the patient’s

obscure bleeding will dictate whether or not evaluation is

pursued as an outpatient or inpatient

Case Resolution and Follow-Up Evaluation

Capsule endoscopy was performed in our patient and bright red blood without specific source was found

14 minutes after the capsule had passed the pylorus, which was estimated to be in the proximal jejunum The area of active bleeding was seen on the capsule images to

be coincident with a lymphangiectasia Push enteroscopy found neither active bleeding, nor another possible source of bleeding, nor the lymphangiectasia An angio-gram of the superior mesenteric artery was unremarkable and showed no extravasation of dye The patient contin-ued to bleed in an accelerated manner and underwent double-balloon enteroscopy A tiny angioectasia was found in juxtaposition to a lymphangiectasia This was treated with argon plasma coagulation No other lesion was found However, some bright red blood accumulated close to the site of initial cautery, although the source of this could not be identified The site was marked with India ink for subsequent surgical resection on the pre-sumption that either there was an angioectasia that could not be visualized or there was a Dieulafoy’s lesion that eluded identification At laparotomy the India ink mark

Figure 2 Algorithm for the detection and management of obscure gastrointestinal bleeding T PA, tissue plasminogen activator; NTG,

Trang 5

nitroglyc-was only 15 cm beyond the ligament of Treitz A nodule

was palpable, which on histology was a submucosal

angioectasia The patient continued to bleed after

sur-gery Capsule endoscopy and double-balloon enteroscopy

were repeated because the ligament of Treitz had been

taken down at surgery to facilitate subsequent

proce-dures Another active bleeding site was found by both

procedures 50 cm distal to the anastomosis, which was

cauterized successfully No further bleeding has occurred

for 2 months

Định dạng
Số trang	5
Dung lượng	180,25 KB