Page 34 - Gastrointestinal Bleeding (Xuất huyết tiêu hóa)

308 PART III Symptoms, Signs, and Biopsychosocial Issues

diffuse locations of the angioectasias. 330 In another study of 33 (4) a first-degree relative with HHT. 337 Genetic testing to detect
patients with iron deficiency anemia and small bowel angio- mutations in the ENG, ALK-1, or SMAD4 genes may be helpful
ectasias seen on push enteroscopy, no changes in clinical or in selected cases. Patients suspected of having HHT should be
endoscopic findings were found in most patients 1 year after screened for cerebral and pulmonary AVMs, and family members
endoscopic therapy. 331 By contrast, in another study of patients of the patient should consider genetic testing.
with GI bleeding suspected from small bowel angioectasia, treat- Telangiectasias can occur anywhere in the small intestine
ment with electrocoagulation led to a significant decrease in (but in patients with HHT. In a case series in which capsule endos-
not elimination of) the need for blood transfusions compared copy was performed in 32 patients with and 48 patients without
with observation alone. 332 In a pilot study of double-balloon HHT who were being evaluated for small bowel bleeding, small
enteroscopy, endoscopic treatment was performed in approxi- bowel telangiectasias were found in 81% of patients with HHT
mately one half of patients with angioectasia, and rebleeding compared with 29% of those without HHT. 338 The telangiecta-
rates during follow up were similar in the treated and nontreated sias were evenly distributed throughout the small bowel, but all
patients. 333 actively bleeding lesions were found in the duodenum or proxi-
In a small case series, hormonal therapy with estrogen was mal jejunum and within reach of a standard push enteroscope.
suggested to have a benefit in controlling bleeding from telan- The detection of 5 or more telangiectasias had a sensitivity of
giectasia in patients with chronic kidney disease. 334 Case reports 75% and a positive predictive value of 86% for a diagnosis of
have suggested that estrogen also decreases bleeding in patients HHT.
with HHT (Osler-Weber-Rendu disease [see later]) and von The treatment of HHT is generally focused on the control of
Willebrand disease. A multicenter randomized controlled trial acute bleeding (epistaxis and GI bleeding), prevention of rebleed-
involving 72 patients, however, found no difference between an ing, and treatment of anemia (with iron supplements). Patients
estrogen-progesterone combination and placebo in the rates of with GI bleeding should undergo endoscopy (or push enteros-
rebleeding, which were 39% and 46%, respectively. 335 Therefore copy) and colonoscopy to look for any GI tract lesions that may
routine use of hormones for managing bleeding from angioecta- be bleeding. Focal GI tract bleeding can be treated with endo-
sia cannot be recommended. scopic coagulation. Hormonal therapy has also been reported as
Thalidomide is an angiogenesis inhibitor that may be effec- a treatment for small bowel bleeding in HHT. 339 Patients who
tive in selected patients with vascular malformations. A random- have symptomatic or large cerebral or pulmonary AVMs should
ized trial that compared thalidomide with oral iron in patients be considered for radiologic embolization of these lesions (see
with angiodysplasia or GAVE revealed that thalidomide-treated Chapter 38).
patients experienced a significant decrease in the number of
bleeding episodes, transfusions, and hospitalizations and in vas- Blue Rubber Bleb Nevus Syndrome
cular endothelial growth factor levels. 336 Until these data are con-
firmed, however, caution is required in the use of thalidomide, Blue rubber bleb nevus syndrome is rare and characterized by
given its potential for serious side effects including birth defects. venous malformations in the skin, soft tissues, and GI tract. 340,341
Most patients with intermittently bleeding GI angioectasia Bleeding usually occurs in childhood and continues into adult-
require medical treatment in addition to endoscopic hemostasis. hood and results in chronic iron deficiency requiring iron
Medications that can exacerbate chronic low-level bleeding (in replacement and transfusions. On endoscopy, lesions appear as
particular, aspirin, other NSAIDs, warfarin, other antiplatelet large protuberant polypoid blue venous blebs; they can occur
agents such as clopidogrel, and direct-acting oral anticoagu- anywhere in the GI tract, but especially in the small bowel and
lants) should be avoided or at least minimized. Many patients colon, and can be treated by endoscopic band ligation or surgical
can be managed with chronic administration of iron (orally or resection (see Chapter 38).
intravenously) and, occasionally, those with renal insufficiency
may need erythropoietin injections as well to maintain adequate Meckel Diverticulum
blood counts, despite ongoing bleeding.
A Meckel diverticulum is a congenital, blind, intestinal pouch
HHT that results from incomplete obliteration of the vitelline duct
during gestation (see Chapter 98). 342 Characteristic features of
HHT, also known as Osler-Weber-Rendu disease, is a heredi- Meckel diverticula have been described by the “rule of 2s”: they
tary condition characterized by diffuse telangiectasias and large occur in 2% of the population, are found within 2 feet of the
AVMs (see also Chapters 38 and 85). The most striking clini- ileocecal valve, are 2 inches long, result in a complication in 2%
cal feature is telangiectasias on the lips, oral mucosa, and finger- of cases, have 2 types of ectopic tissue (gastric and pancreatic)
tips. Additionally, up to one third of patients have pulmonary, within the diverticulum, present clinically most commonly at
hepatic, or cerebral AVMs (see Chapter 85). Patients generally age 2 (with intestinal obstruction), and have a male-to-female
present with recurrent severe nosebleeds, GI bleeding, and iron ratio of more than 2:1. The most common complications of
deficiency anemia. Usually the epistaxis, rather than GI bleed- Meckel diverticula are bleeding, obstruction, and diverticulitis,
ing, causes the more profound blood loss and anemia. HHT can which can occur in children or adults. Histopathologic evalu-
be life-threatening because of embolic strokes or brain abscesses ation of bleeding diverticula reveals ectopic gastric mucosa,
related to the pulmonary and cerebral AVMs. Symptoms of HHT which can lead to acid secretion and ulceration in up to 75%
generally develop in childhood or early adulthood. of patients. The diagnostic test for a Meckel diverticulum is a
HHT is inherited as an autosomal dominant trait, with varying 99m Tc-pertechnetate scan (Meckel scan) because technetium
phenotypic expression. Mutations occur in at least 4 genes (ENG pertechnetate has an affinity for gastric mucosa. Meckel scans
[encodes endoglin, type 1 HHT or HHT1], ALK-1 [encodes have a high specificity (almost 100%) and positive predictive
activin receptor-like kinase 1, type 2 HHT or HHT2], SMAD4, value but can be negative in the 25% to 50% of patients in whom
and HHT3) that encode proteins needed to maintain the integrity the diverticulum does not contain ectopic gastric mucosa. 343
of the vascular endothelium; defects in these proteins allow the The accuracy of the Meckel scan can be improved with admin-
formation of AVMs. istration of an H2RA for 24 to 48 hours before the test. Meckel
The diagnosis of HHT is based on 4 criteria: (1) spontane- diverticula also have been diagnosed by CT enterography, cap-
ous and recurrent epistaxis, (2) multiple mucocutaneous telan- sule endoscopy, or double-balloon enteroscopy (via an oral or
giectasias, (3) visceral AVMs (GI, pulmonary, brain, liver), and rectal approach).