GASTROINTESTINAL BLEEDING OVERVIEW

The many causes of gastrointestinal (GI) bleeding are classified into upper or lower, depending on their location in the GI tract.



Upper gastrointestinal bleeding: Upper GI bleeding originates in the first part of the GI tract-the esophagus, stomach, or duodenum (first part of the intestine). Bleeding can come from ingestion of caustic poisons or stomach cancer. Most often, upper GI bleeding is caused by one of the following:


Peptic ulcers


Gastritis


Esophageal varices


Mallory-Weiss tears


Lower gastrointestinal bleeding: Lower GI bleeding originates in the portions of the GI tract farther down the digestive system-the segment of the small intestine farther from the stomach, large intestine, rectum, and anus. Diverticular disease, angiodysplasia, polyps, hemorrhoids, and anal fissures most commonly cause the bleeding. Blood in the stool can result from cancers, inflammatory bowel disease, and infectious diarrhea.

Gastrointestinal Bleeding Causes
The many causes of gastrointestinal bleeding are classified into upper or lower, depending on their location in the GI tract.

Upper GI bleeding

Peptic ulcer disease: Peptic ulcers are localized erosions of the wall of the digestive tract. Ulcers usually occur in the stomach or duodenum. Breakdown of the walls results in damage to blood vessels, causing bleeding. When the mucous membranes break down, they are unable to counteract the harsh effects of stomach acid. Nonsteroidal anti-inflammatory drugs (NSAIDs), aspirin, alcohol, and cigarette smoking promote gastric ulcer formation. Helicobacter pylori are a type of bacteria that also promote formation of ulcers.

Gastritis: General inflammation of the stomach wall, which can result in bleeding. Gastritis also results from an inability of the gastric lining to protect itself from the acid it produces. NSAIDs, steroids, alcohol, burns, and trauma can cause gastritis.

Esophageal varices: Swellings in veins of your esophagus or stomach usually result from liver disease. Varices most commonly result from alcoholic liver cirrhosis. When varices bleed, the bleeding can be massive and catastrophic and occur without warning.

Mallory-Weiss tear: A tear in the esophageal or stomach wall, often as a result of vomiting or retching. Tears also can occur after seizures, forceful coughing or laughing, lifting, straining, or childbirth. Physicians often find tears in people who have recently binged on alcohol.
Lower GI bleeding

Diverticulosis: One of the most common causes of lower GI bleeding. Small out-pockets, or diverticula, form on part of the wall of your colon (large intestine), usually in a weakened area of the bowel wall. You may develop several pockets, which are more common in people who have constipation and strain at stool.

Angiodysplasia: Along with diverticulosis, this is one of the most common causes of lower GI bleeding. Angiodysplasia is a malformation in the blood vessels in the wall of the GI tract. The sores are most common in the large intestine and often bleed. The elderly and people with chronic kidney failure develop the disease most often.

Polyps: Intestinal polyps are noncancerous tumors of the GI tract, occurring mostly in people older than 40 years. A small proportion of these polyps may transform into cancer. Colonic polyps may bleed rapidly, or they may bleed slowly and go undetected.

Hemorrhoids and fissures: Hemorrhoids are swellings of veins in and around your rectum. Repeated stretching from straining at stool causes them to bleed. Bleeding from hemorrhoids is usually mild, intermittent, and bright red. Massive bleeding is rare. Anal fissures, or tears in the anal wall, also may trigger small amounts of bright red bleeding from the anus. Forceful straining during passage of hard stool usually causes such tears, which can be very painful.

source:webmd.com