Meckel Diverticulum Class Notes

Meckel Diverticulum Definitions: • • • • • • A congenital outpouching in the lower parts of the intestine. It is a left over of the umbilical cord. The most common congenital anomaly of the gastrointestinal tract and is caused by an incomplete obliteration of the omphalomesenteric duct. It is generally about 2 inches long and is located 2 feet proximal to the ileocecal valve. The mucosal lining of the diverticulum may be native ileal mucosa r heterotopic mucosa. it is often asymptomatic and detected incidentally on imaging or abdominal surgery. Epidemiology • • Most common congenital anomaly of the gastrointestinal tract. Affects males more than females at a ratio of 2:1. Pathophysiology • • • The omphalomesenteric duct (vitelline or Vitello intestinal) is a patent tubular structure that connects the yolk sac to the alimentary tract in the embryo. The duct is normally obliterated by the 6th and 7th week of intrauterine life. Incomplete obliteration of the omphalomesenteric duct -> persistence of the proximal (intestinal) segment of the duct -> Meckel diverticulum. Clinical features • • Asymptomatic: - The most common manifestation. - Detected incidentally on imaging or during surgery (laparoscopy/laparotomy) performed fir unrelated condition. Symptomatic: - Lower gastrointestinal bleeding -> most common features. ✓ Presence of ectopic gastric mucosa or pancreatic tissue -> acid or enzyme secretion within the diverticulum -> ileal ulceration -> bleeding. ✓ Can manifest as: ➢ Hematochezia -> indicates a brisk haemorrhage. ➢ Tarry stools -> indicates a slow haemorrhage. ➢ Currant jelly stools -> indicated intussusception with bowel ischemia. ✓ Abdominal pain -> typically in the right lower quadrant. ✓ Nausea and vomit Diagnostics • • Imaging: - Indications: hemodynamically stable patients with lower GIT bleeding. ✓ Children less than 10 years old. ✓ Adults with no abnormalities detected on endoscopy/colonoscopy/CT scan. - Meckel scan: a non-invasive nuclear medicine imaging technique that uses radiolabelled technetium (99mTc), which is preferentially absorbed by the gastric mucosa and can identify ectopic gastric mucosa. - CT angiography: may demonstrate the vitelline artery or contrast extravasation from a bleeding Meckle diverticulum. - Other imaging tests: mesenteric arteriography and tagged RBC scans: useful to detect a bleeding Meckel diverticulum. - Double ballon enterostomy: an endoscopic technique to visualise the entire small bowel. ✓ A long endoscopic is advanced, either through the mouth or the rectum into the small intestine. ✓ The sequence inflation and deflation of the two balloons helps advance the scope into the intestine by pleating the bowel onto the scope. - Capsule endoscopy: a diagnostic procedure using a tiny wireless camera fitted inside a capsule that is swallowed by the patient to take pictures of the mucosa as it passes through the GI tract. ✓ The patient swallows the encapsulated camera. ✓ Pictures are analysed after the capsule is excreted 24 to 48 hours later. Diagnostic laparoscopy: - Meckel diverticulum may be identified on diagnostic laparoscopy performed on (hemodynamically stable) patients with acute abdomen/lower GIT bleeding and negative findings using other investigations. Treatment • Asymptomatic: - Incidentally detected on imaging studies -> no treatment necessary. - Incidentally detected on laparoscopy/laparotomy. ✓ Children or young adults: surgical resection of all incidentally detected Meckel diverticula. ✓ Adults less than 50: surgical resection only for Meckel diverticula that have a high risk of developing complications. ➢ A Meckel diverticulum is more than 2 cm long, has a board base that is more than 2 cm wide, and has a palpable abnormality, or a fibrous band attaching it to the umbilicus. ✓ Adults more than 50: no treatment is necessary. ➢ This is because there is a low risk of it becoming symptomatic after 50 years old. ➢ The only exception to this, is when there is a palpable abnormality associated with the diverticulum. Complications • • • • • Haemorrhage -> most common. Bowel obstruction (usually affects the terminal ileum) due to: - Intussusception. - Volvulus: the presence of a fibrous band or bands between the umbilicus and Meckel diverticulum can cause twisting of the small intestine around the fibrous band (volvulus). Bowel perforation: peritonitis or intraabdominal abcess. Infection (Meckel diverticulitis): patients present with acute lower abdominal pain, mimicking acute appendicitis or acute mesenteric lymphadenitis. Neoplasia (rare): - Benign tumours: e.g. leiomyoma is the most common. - Leiomyosarcoma, carcinoid tumours, lipomas, fibromas, and angiomas may also be found.