دانلود رایگان مقاله انگلیسی تصویربرداری از خونریزی گوارشی حاد و غلیظ - الزویر 2018

INTRODUCTION

Lower gastrointestinal (GI) bleeding is a frequent cause for hospital admissions with an annual incidence of approximately 20 to 27 cases per 100,000 persons in the United States.1 Morbidity and mortality vary according to the underlying cause of the GI bleed, with reported mortality rates of 2% to 20% for lower GI bleeding and as high as 40% for hemodynamically unstable patients.2 Lower GI bleeding is defined as bleeding that occurs distal to the ligament of Treitz, with upper GI bleeding occurring proximally. Clinical presentations vary based on the source of the bleed and cause; however, acute lower GI bleeds typically present with hematochezia, noting that secondary to the cathartic effects of blood, a brisk upper GI bleed may present in a similar manner.3 Causes of lower GI bleeding may be anatomic, such as diverticulosis (33.5%); vascular, such as hemorrhoids (22.5%), angioectasia, or ischemia; neoplastic (12.7%); inflammatory as with inflammatory bowel disease; or infectious.4 If the workup of the large bowel is negative, then patients are suspected of having a small bowel bleed. There are several classification schemes used to describe lower GI bleeding related to the duration and severity of the bleed as well as the results of upper and lower endoscopy/imaging. When correlating with the amount of bleeding, lower GI bleeds can be categorized as massive, moderate, or occult. Massive bleeding is defined by the passage of profuse hematochezia with hemodynamic instability. Moderate bleeding reflects hematochezia in hemodynamically stable patients.

SUMMARY

Lower GI bleeding occurs distal to the ligament of Treitz and is an important clinical problem with a variety of causes. The bleeding can be acute, presenting with hematochezia, or occult, presenting with iron deficiency anemia and/or positive fecal occult blood test. Obscure bleeding refers to patients with rebleeding after a negative endoscopic and radiologic assessment of the bowel. The workup of lower GI bleeding includes endoscopy, CTA, CTE, nuclear scintigraphy, conventional angiography, and surgery. The clinical presentation of patients dictates the order and urgency that the test/intervention is performed. Radiologic assessment of lower GI bleeding has come to the forefront of the workup, especially in patients with acute ongoing bleeding. Conventional angiography with embolization is now often the first-line treatment in patients who are unstable. CTE has become a first-line test for many patients with occult GI bleeding, especially in those whereby there is a contraindication to capsule endoscopy. This article discusses the various imaging modalities used in the workup of lower GI bleeding and includes some of the common imaging findings using each modality.