Gastrointestinal (GI) Bleeding

Introduction

Gastrointestinal bleeding (GIB) is a common clinical problem, the presentation of which may be acute or chronic. GIB is classified as arising from the upper (proximal to ligament of Treitz) or lower (distal to the ligament of Treitz) GI tract.

Classically, acute upper GIB (UGIB) presents with overt hematemesis or melena, while acute lower GIB (LGIB) presents with hematochezia, although there is substantial overlap in clinical presentation, particularly with a very brisk UGIB causing hematochezia. Chronic GIB may manifest as anemia and heme-positive stools, ± perceptible changes in appearance of the stool, and thus can be further subclassified into "overt" or "occult" presentations.

Overt GIB designates visible blood in the stool, whereas occult GIB implies that the stool has a normal appearance despite the presence of detectable blood products. Another important definition is that of "obscure" GIB , which means that after a thorough evaluation by esophagogastroduodenoscopy (EGD) and colonoscopy , the cause of bleeding remains unidentified. This usually indicates a source beyond the reach of the standard endoscopes, i.e., the small bowel, and it has been proposed recently that the term "suspected small bowel bleeding" replace "obscure GIB," and the "obscure" designation be reserved for causes of bleeding, which remain unknown after a thorough investigation of the entire GI tract. This reflects the fact that in recent years we have developed more effective tools (video capsule endoscopy, deep enteroscopy, and radiologic imaging) to diagnose small bowel bleeding.

In the past, acute UGIB was more common than LGIB; however, there has been a striking decrease in upper GI events and increase in lower GI events, which are now nearly equal in incidence. The most common causes of UGIB are peptic ulcers , gastroduodenal erosions, esophagitis, esophageal and gastric varices , Mallory Weiss tears , and vascular malformations. The diagnosis and management of variceal hemorrhage are outside the scope of this chapter. Therefore, UGIB subsequently will refer to nonvariceal UGIB. The most common causes of LGIB depend on the age group. In younger people, inflammatory bowel disease (IBD) and Meckel diverticulum are most prevalent. In older individuals, diverticular hemorrhage, angiodysplasia, and colon cancer are most common.

In the evaluation of patients with acute GIB, most commonly encountered in the emergency department, the 1st step is to do a thorough history, physical, and laboratory evaluation. This should include a digital rectal examination, as well as placement of a nasogastric tube, in an attempt to determine if the hemorrhage has an upper GI source. Hemodynamic stabilization and resuscitation, correction of coagulopathy if present, administration of available pharmacologic treatments (e.g., somatostatin, acid suppression, etc.), and gastroenterology consultation are prioritized in preparation for an efficient and focused diagnostic evaluation. In appropriately risk-stratified patients with suspected UGIB, the 1st step is usually EGD, while in LGIB, the 1st step is more variable and may include EGD, colonoscopy, or radiologic testing depending on the clinical situation and local practice patterns.