ASGE Recognized Industry Associate (ARIA) Training Program OPEN | October 2025-GI Tract in Disease_Large Intestine_Lower GI Bleeding_Colorectal Cancer

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This document provides an overview of key gastrointestinal tract diseases focusing on the large intestine, particularly colorectal cancer, lower gastrointestinal (GI) bleeding, diverticulosis, and hemorrhoids.<br /><br />Colorectal cancer, a common U.S. cancer with a lifetime risk of about 5%, develops over 10-15 years, progressing from hyperproliferation to adenomatous polyps, high-grade dysplasia, and invasive adenocarcinoma. It may be asymptomatic or present with suspicious symptoms or emergently with obstruction or peritonitis. Screening is recommended starting at age 45 or earlier with risk factors (family history, inherited syndromes, inflammatory bowel disease) using tests like fecal occult blood or immunochemical tests, stool DNA analysis, flexible sigmoidoscopy, colonoscopy, or CT colonography. Diagnosis is confirmed by colonoscopy. Localized tumors are treated surgically; metastatic disease is managed with chemotherapy and palliative care.<br /><br />Lower GI bleeding usually originates beyond the ligament of Treitz, mostly from the colon (85%), presenting with hematochezia (bright red rectal bleeding) or melena (black stools), and symptoms of anemia like lightheadedness and syncope. Causes include diverticulosis, angiodysplasia, ischemic colitis, inflammatory bowel disease, infections, malignancy, iatrogenic causes, and hemorrhoids. Management includes volume resuscitation, excluding upper GI bleeding with nasogastric lavage, and colonoscopy for diagnosis and hemostatic interventions such as hemoclipping, argon plasma coagulation, banding, or epinephrine injection.<br /><br />Diverticulosis involves mucosal and submucosal outpouchings increasing with age, mostly asymptomatic but can lead to diverticulitis (inflammation with left-sided pain, fever) or diverticular bleeding (painless rectal bleeding). Diverticulitis is diagnosed by CT scan and treated with antibiotics or surgery for complications. Diverticular bleeding is often self-limited; severe cases require colonoscopy, angiography, or surgery.<br /><br />Hemorrhoids are swollen anal veins caused by factors like age, pregnancy, constipation, or straining, diagnosed by examination and anoscopy. Treatment ranges from conservative management (diet, topical steroids, sitz baths) to procedures (rubber band ligation, sclerotherapy) or surgery (hemorrhoidectomy).<br /><br />Overall, this summary captures essential clinical features, diagnostic approaches, and treatments for colorectal diseases affecting the lower GI tract.

Asset Subtitle

Kunjali Padhya, MD

Keywords

colorectal cancer

lower gastrointestinal bleeding

diverticulosis

hemorrhoids

colonoscopy

diverticulitis

fecal occult blood test

adenomatous polyps

hemoclipping

rubber band ligation