Q1: Describe the features on the barium follow through (see 303)

The barium meal follow through reveals a 4 cm × 1 cm sausage shaped pedunculated polyp in the distal ileum, which is lying 40–50 cm proximal to the ileocaecal valve.

Q2: What is the differential diagnosis?

The differential diagnosis includes lipoma, inflammatory fibroid polyp, other pedunculated polyps such as those associated with Peutz-Jeghers syndrome and familial adenomatosis polyposis syndrome, and an inverted Meckel's diverticulum.

Q3: What is the diagnosis?

This patient underwent an exploratory laparotomy, which revealed a Meckel's diverticulum. A segment of ileum was resected and an end-end anastamosis was performed. The specimen was cut open to reveal an inverted Meckel's diverticulum.

The histology of the specimen revealed Meckel's diverticulum with evidence of past ulceration with pyloric gland metaplasia and Paneth cell hyperplasia.

Discussion

Most sources of gastrointestinal blood loss can be diagnosed with upper or lower gastrointestinal endoscopy, but 5% of gastrointestinal bleeding episodes are occult and caused by a variety of lesions within the jejunum or ileum.¹ We present a rare case of chronic gastrointestinal bleeding caused by an inverted Meckel's diverticulum.

Meckel's diverticulum is the most common congenital abnormality of the small intestine, seen in 0.3%–3% of the population at necropsy. It results from the persistence of the omphalomesenteric (vitelline) duct, which is an embryonic connection between the midgut and the umbilical cord. It arises from the antimesenteric border of the ileum, and contains all layers of the intestinal wall, has its own mesentery, and derives its blood supply from a terminal branch of the superior mesenteric artery.

Painless, often haemodynamically significant, but usually not life threatening, lower intestinal bleeding is a common presentation. Bleeding is more common in children and occurs at a mean age of 5 years. Haemorrhage typically results from ulceration within the diverticulum or adjacent intestinal mucosa as a consequence of acid secretion from ectopic gastric mucosa. There is a debate about the prevalence of Meckel's diverticulum in males versus females, however complications occur more frequently in males.²

Intestinal obstruction due to Meckel's diverticulum is more common in older patients and can be caused by intussusception, volvulus, herniation, or entrapment of bowel through a defect in the diverticular mesentery. Symptoms mimicking acute appendicitis can occur as a result of Meckel's diverticulitis, H pylori infection of the ectopic gastric mucosa, or a foreign body in the diverticular lumen.

On barium examination an inverted Meckel's diverticulum is seen as a solitary elongated club shaped mass (with or without intussusception) in the distal ileum.³ If intussusception occurs, ultrasound demonstrates a target sign with alternating layers of different attenuation with a low attenuation centre. It is important to be aware of the radiological features of inverted Meckel's diverticulum, as surgical removal of these lesions is warranted in most cases.

The appearances of an inverted Meckel's diverticulum on barium examination are shown. It is important to recognise the abnormality so that resection can be performed to avoid the serious complications of intussusception and bleeding.

Final diagnosis

Meckel's diverticulum.