Gastrointestinal Bleeding

Upper GI Inflammation/Ulcer

The mucosal lining of the esophagus, stomach, and duodenum is especially susceptible to inflammation from infection, radiation therapy, damage caused by ingested materials such as alcohol and oral medications, and exposure to stomach acid and digestive enzymes. Initially, simple abrasion and erosion of the mucosal lining may be followed by a more severe lesion, which penetrates deeper layers of the gut wall, exposing blood vessels and underlying tissue. Repeated insult and resulting compensatory replacement of lining cells can also lead to the development of cancers also capable of damaging the luminal covering.

The most common etiology of an inflamed esophagus is gastroesophageal reflux disease, characterized by heartburn and abnormal acid reflux due to a dysfunctional lower esophageal sphincter. In the stomach and duodenum, peptic ulcers are caused by overproduction of hydrochloric acid by parietal cells in gastric glands due to hormonal or parasympathetic nervous stimulation. A majority of cases are also strongly associated with bacterial infections of Helicobacter pylori which invade gastric pits and cause autodigestion of the stomach wall by gastric enzymes.

Anatomical Malformations/Age-Related Weakening

Various anatomical malformations may also contribute to the etiology of gastrointestinal bleeding. On its course to the stomach, the esophagus passes from the chest cavity to the abdomen through a hole in the muscular diaphragm called the esophageal hiatus. In enlarged or age-related weakened openings, the upper cardiac part of the stomach herniates through the diaphragm into the chest cavity, increasing regurgitation and likelihood of bleeding characteristic of acid reflux. In very rare cases, torsion and volvulus or twisting of the gut may cause mechanical stress induced bleeding.

Diverticulitis

Diverticulitis a condition associated with diet, constipation, and obesity, involves small outward herniation of the gut lining through small, natural, peripheral openings created by perforating intestinal nutrient arteries. Thin outpouches, of gut wall, are highly susceptible to perforation from fecal blockage, resulting in intestinal bleeding and other complications

Lower GI Inflammation

Inflammatory bowel disease is a broad category of conditions including ulcerative colitis, Crohn's disease, and postinflectional colitis. Inflammation that arises from infection, genetic influence, immune abnormalities, stress, food allergy, or idiopathic causes may be significant enough to cause ulcerations and bleeding in the lower bowel. In Crohn's disease, these lesions are deeper, discontinuous, and may occur along the entire digestive tract.

Varices/Hemorrhoids/Polyps

Veins draining deoxygenated blood from the gut tube carry newly absorbed nutrients first to the liver through portal circulation before draining into the inferior vena cava and heart for pulmonary circulation. Portal hypertension is a condition resulting in impeded blood flow to the liver, causing enlargement, thinning, and increased blood pooling and pressure in portal veins that drain the gut.

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