A Meckels 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. Meckels 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. Signs and symptoms
The majority of people with a Meckels diverticulum are asymptomatic. An asymptomatic Meckels diverticulum is called a silent Meckels diverticulum. If symptoms do occur, they typically appear before the age of two years. The most common presenting symptom is painless rectal bleeding such as melaena-like black offensive stools, followed by intestinal obstruction, volvulus and intussusception. Occasionally, Meckels diverticulitis may present with all the features of acute appendicitis. Also, severe pain in the epigastric region is experienced by the person along with bloating in the epigastric and umbilical regions. At times, the symptoms are so painful that they may cause sleepless nights with acute pain felt in the foregut region, specifically in the epigastric and umbilical regions. In some cases, bleeding occurs without warning and may stop spontaneously. The symptoms can be extremely painful, often mistaken as just stomach pain resulting from not eating or constipation.
This occurs when the diverticulum inverts into the lumen of the ileum, due to either:An active peristaltic mechanism of the diverticulum that attempts to remove irritating factors
A passive process such as the transit of food

Umbilical anomalies
Anomalies between the diverticulum and umbilicus may include the presence of fibrous cord, cyst, fistula, or sinus, leading to:
Infection or excoriation of periumbilical skin, resulting in a discharging sinus
Recurrent infection and healing of sinus
Abscess formation in the abdominal wall
Fibrous cord increases the risk of volvulus formation and internal herniation

Neoplasm
Tumors in Meckels diverticulum may cause bleeding, acute abdominal pain, gastrointestinal obstruction, perforation or intussusception. Benign tumors:Leiomyoma
Lipoma
Vascular and neuromuscular hamartomaMalignant tumors:Carcinoids: most common, 44%
Mesenchymal tumors: Leiomyosarcoma, peripheral nerve sheath and gastrointestinal stromal tumors, 35%
Adenocarcinoma, 16%
Desmoplastic small round cell tumor

Other complications
A diverticulum inside a Meckels diverticulum (daughter diverticula)
Stones and phytobezoar (a bezoar of vegetable fibers) in Meckels diverticulum
Vesicodiverticular fistula

Pathophysiology
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 of gestation.In Meckels 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.