Emmetropization The coordination of the power of the cornea, crystalline lens, and axial length to process a sharp retinal image of a distant object is known as emmetropization. In the United States, more than 70 percent of the population is either emmetropic or mildly hyperopic (easily corrected with a small accommodative effort). With age, the cornea, …
What is the presumed cause of appendicitis in adults or children? Intestinal concretions around fecal matter, or fecaliths (in adults) or hypertrophied lymphoid tissue causing obstruction of the lumen (in children), are the dominant etiologic factors. Fecaliths are found in approximately 90% of cases of gangrenous, ruptured appendicitis. The luminal obstruction causes distention of the …
Anatomy of the appendix. Does it have a function in humans? The vermiform appendix (from Latin, vermiform or wormlike, and appendere, to hang upon) is usually 6 to 9 cm in length, arising from the convergence of the three taenia coli at the base of the cecum. It is now considered an immunologic organ that participates actively in the …
What is radiation colitis? Radiation colitis refers to radiation-induced changes in the mucosa of the colon and rectum. Generally, radiation colitis is a chronic, ischemic process caused by obliterative endarteritis, in contrast to acute inflammation seen in other types of colitis. Which part of the GI tract is most commonly injured by radiation? Radiation injury …
What is Clostridium difficile? First isolated in 1935 and named for its difficult isolation from the feces of infants, Bacillus difficile is an anaerobic, gram-positive, spore-forming, toxin-producing bacteria spread by the fecal-oral route. By the 1970s, this bacillus was renamed Clostridium difficile and its toxins were implicated as a major cause of diarrhea and as the cause of pseudomembranous colitis …
How are aspirin and NSAIDs managed following an episode of peptic ulcer bleeding? Patients with bleeding peptic ulcer disease should be tested and treated for Helicobacter pylori infection. Eradication of infection should be documented. NSAIDs should be stopped. If this is not possible, a coxib plus a PPI should be used. In general, low-dose aspirin for secondary …
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What is the management of nonvariceal UGI bleeding that is refractory to initial endoscopic management? Initial endoscopic therapy is successful in obtaining permanent control of bleeding in 80% to 90% of patients with nonvariceal UGI bleeding. In patients with recurrent bleeding after endoscopic therapy, approximately 70% will be controlled after a second attempt at endoscopic …