<s>[INST] context: Meckel diverticulum, caused by persistence of the vitelline duct and, on the antimesenteric ileal border, 60 to 100 cm from the ileocecal valve in adults. It is the most common and the most clinically significant congenital anomaly of the small intestine. Two thirds of patients are younger than 2 years. The omphalomesenteric duct (omphaloenteric duct, vitelline duct or yolk stalk) normally connects the embryonic midgut to the yolk sac ventrally, providing nutrients to the midgut during embryonic development. The vitelline duct narrows progressively and disappears between the 5th and 8th weeks gestation. In Meckel's diverticulum, the proximal part of vitelline duct fails to regress and involute, which remains as a remnant of variable length and location. The solitary diverticulum lies on the antimesenteric border of the ileum (opposite to the mesenteric attachment) and extends into the umbilical cord of the embryo. The left and right vitelline arteries originate from the primitive dorsal aorta, and travel with the vitelline duct. The right becomes the superior mesenteric artery that supplies a terminal branch to the diverticulum, while the left involutes. Having its own blood supply, Meckel's diverticulum is susceptible to obstruction or infection. Meckel's diverticulum is located in the distal ileum, usually within 2-3 feet (60-100 cm) 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. 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. 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. 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: 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 Littre". 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. [/INST] question: The Meckel&;s diverticulum is situated at a maximum distance of about____ cm from the ileocecal valve - | options: A: 25 B: 60 C: 75 D: 100 | answer: D </s>