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A Meckel's diverticulum, a true congenital diverticulum, is a slight bulge in the small intestine present at birth and a vestigial remnant of the omphalomesenteric duct (also called the vitelline duct or yolk stalk). It is the most common malformation of the gastrointestinal tract and is present in approximately 2% of the population, with males more frequently experiencing symptoms. Meckel's diverticulum was first explained by Fabricius Hildanus in the sixteenth century and later named after Johann Friedrich Meckel, who described the embryological origin of this type of diverticulum in 1809.〔J. F. Meckel. Über die Divertikel am Darmkanal. Archiv für die Physiologie, Halle, 1809, 9: 421–453.〕 ==Presentation== Meckel's diverticulum is located in the distal ileum, usually within 60–100 cm (2 feet) of the ileocecal valve. This ''blind segment'' or small pouch is about 3–6 cm long and may have a greater lumen diameter than that of the ileum.〔Moore, K. L., Persaud, T. V. N., & Torchia, M. G. (2013). The developing human: Clinically oriented embryology (9th ed.). Philadelphia: Elsevier/Saunders.〕 It runs antimesenterically and has its own blood supply. It is a remnant of the connection from the yolk sac to the small intestine present during embryonic development. It is a ''true diverticulum'', consisting of all 3 layers of the bowel wall which are mucosa, submucosa and muscularis propria.〔Mattei, P. (2011). Fundamentals of Pediatric Surgery. New York, NY: Springer Science+Business Media, LLC.〕 As the vitelline duct is made up of pluripotent cell lining, Meckel’s diverticulum may harbor abnormal tissues, containing embryonic remnants of other tissue types. Jejunal, duodenal mucosa or Brunner's tissue were each found in 2% of ectopic cases. Heterotopic rests of gastric mucosa and pancreatic tissue are seen in 60% and 6% of cases respectively. Heterotopic means the displacement of an organ from its normal anatomic location.〔Robbins, S. L., Kumar, V., & Cotran, R. S. (2010). Robbins and Cotran pathologic basis of disease (8th ed.). Philadelphia, PA: Saunders/Elsevier〕 Inflammation of this Meckel's diverticulum may mimic appendicitis. Therefore during appendectomy, ileum should be checked for the presence of Meckel's diverticulum, if it is found to be present it should be removed along with appendix. A memory aid is the rule of 2s:〔F. Charles Brunicardi, Dana K. Anderson, Timothy R. Billiar, et al. Small Intestine. In: Ali Tavakkoli, Stanley W. Ashley, Michael J. Zinner: Schwartz's Principles of Surgery. 10 ed. United states: McGraw-Hill;2015〕 *''2%'' (of the population) *''2'' feet (proximal to the ileocecal valve) *''2'' inches (in length) *''2'' types of common ectopic tissue (gastric and pancreatic) *''2'' years is the most common age at clinical presentation *''2'':1 male:female ratio However, the exact values for the above criteria range from 0.2–5 (for example, prevalence is probably 0.2–4%). It can also be present as an indirect hernia, typically on the right side, where it is known as a "''Hernia of Littré''". A case report of strangulated umbilical hernia with Meckel's diverticulum has also been published in the literature. Furthermore, it can be attached to the umbilical region by the vitelline ligament, with the possibility of vitelline cysts, or even a patent vitelline canal forming a vitelline fistula when the umbilical cord is cut. Torsions of intestine around the intestinal stalk may also occur, leading to obstruction, ischemia, and necrosis. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Meckel's diverticulum」の詳細全文を読む スポンサード リンク
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