What is meckel diverticulum?

It is a blind outpouching of alimentary tract communicates w/lumen, most common is Meckel diverticulum, in ileum. Less common in small intestine and ascending colon. Characteristics (rule of 2): 2% of population, 2 feet of ileocecal valve, 2 inches long, twice more common in males, often symptomatic age 2 (4% only symptomatic). It occurs as a result of failed involution of vitelline duct connecting lumen of developing gut to yolk sac, it extends from antimesenteric side of the bowel. All diverticuli are acquired and may lack muscularis or have attenuated muscularis propria, mucosa resembles small intestine, but may present ectopic pancreas/gastric tissue, secrete acid cause peptic ulceration of small intestine mucosa present w/occult bleeding/abdo pain.