or alkaline pancreatic juice from the ectopic mucosa leads to ulceration in the adjacent ileal mucosa i.e. peptic or pancreatic ulcer. Pain, bleeding or perforation of the bowel at the diverticulum may result. Mechanical stimulation may also cause erosion and ulceration. Gastrointestinal bleeding may be self-limiting but chronic bleeding may lead to iron deficiency anaemia. The appearance of stools may indicate the nature of the bleeding: Tarry stools: Alteration of blood produced by slow bowel transit due to minor bleeding in upper gastrointestinal tract Bright red blood stools: Brisk bleeding Stools with blood streak: Anal fissure "Currant jelly" stools: Ischaemia of the intestine leads to copious mucus production and may indicate that one part of the bowel invaginates into another intussusception. Diverticulitis Inflammation of the diverticulum can mimic symptoms of appendicitis, i.e., periumbilical tenderness and intermittent crampy abdominal pain. Perforation of the inflamed diverticulum can result in peritonitis. Diverticulitis can also cause adhesions, leading to intestinal obstruction. Diverticulitis may result from: Association with the mesodiverticular band attaching to the diverticulum tip where torsion has occurred, causing inflammation and ischaemia. Peptic ulceration resulting from ectopic gastric mucosa of the diverticulum Following perforation by trauma or ingested foreign material e.g. stalk of vegetable, seeds or fish/chicken bone that become lodged in Meckel's diverticulum. Luminal obstruction due to tumors, enterolith, foreign body, causing stasis or bacterial infection. Association with acute appendicitis Intestinal obstruction Symptoms: Vomiting, abdominal pain and severe or complete constipation. The vitelline vessels remnant that connects the diverticulum to the umbilicus may form a fibrous or twisting band (volvulus), trapping the small intestine and causing obstruction. Localised periumbilical pain may be experienced in the right lower quadrant (like appendicitis). "Incarceration": when a Meckel's diverticulum is constricted in an inguinal hernia, forming a Littré hernia that obstructs the intestine. Chronic diverticulitis causing stricture Strangulation of the diverticulum in the obturator foramen. Tumors e.g. carcinoma: direct spread of an adenocarcinoma arising in the diverticulum may lead to obstruction Lithiasis, stones that are formed in Meckel's diverticulum can: Extrude into the terminal ileum, leading to obstruction Induce local inflammation and intussusception. The diverticulum itself or tumour within it may cause intussusception. For example, from the ileum to the colon, causing obstruction. Symptoms of this include "currant jelly" stools and a palpable lump in the lower abdomen. This occurs when the diverticulum inverts into the lumen of the ileum, due to either: An active peristaltic