Meckel's Diverticulum

This is the vestigial remnant of the vitellointestinal duct. It is the most frequent malformation of the gastrointestinal tract. If present, it is located in the distal ileum, usually within 100cm of the ileocecal valve.¹

Autopsy records show an incidence of about 2% in the general population. For asymptomatic diverticula there is no gender predominance,. For symptomatic diverticula some studies give a 3:1 male to female ratio, while others have detected little difference.^2,3 The risk of complications ranges from 4-25% in various studies.³

Asymptomatic

Meckel's is a common incidental finding at laparotomy. Complications are most likely to occur when the diverticulum contains heterotypic tissue (approximately 60%) - usually gastric (80%), pancreatic, jejunal or colonic mucosa. One study found that the lifetime risk of developing a complication that required surgery was 6.4%.

Haemorrhage

This accounts for 20-30% of all complications.It is commoner in children younger than 2 years and in males.The patient usually reports bright red blood in the stools. The amount may very from minimal recurrent episodes to a large shock-producing haemorrhage. Meckel's should always be excluded in a child presenting with massive painless rectal bleeding.

The blood may be bright red if the bleeding is brisk , or darker if it is milder and transit time is slow. Melaena-like tarry stool may also be seen if gastric tissue present in the diverticulum ulcerates, or produced acid which damages the adjacent ileal mucosa.

Intestinal obstruction

This presents in 10-20% of symptomatic patients. The presenting symptoms are usually abdominal pain, vomiting and constipation. The pain may be anywhere in the abdomen but when located in the RIF can mimic appendicitis ('Meckel's diverticulitis').Various mechanisms produce the obstruction, including a fibrotic band attaching the diverticula the abdominal wall may be found causing a volvulus of the small bowel, and intussusception in which the diverticulum is the lead point. An intussusception may present with redcurrant jelly stools or a palpable lump in the lower abdomen.

Umbilical anomalies

These occur in up to 10% of patients. The anomalies may include fistulas, cysts, sinuses, and fibrous bands between the diverticulum and the umbilicus. There may be a history of recurrent infection, chronic sinus formation, abdominal wall abscess formation and infection of excoriation of the periumbilical skin.

Neoplasm

This is extremely rare and has been reported in approximately 4-5% of complicated diverticula. Various types of tumour can occur, including leiomyoma, leiomyosarcoma, carcinoid, and fibroma.

Miscellaneous

Other complications that have been reported include the formation of stones and phytobezoar, vesicodiverticular fistulas and 'daughter diverticula' (formation of a diverticulum within a Meckel's diverticulum).

Meckel's diverticulum should always be considered in the differential diagnosis of patients presenting with rectal bleeding or intestinal obstruction.
Investigations are dictated by the type of complication. For paediatric patients presenting with haemorrhage and a suspected Meckel's diverticulum, Technetium-99m pertechnetate scintigraphy is the modality of choice.⁴

In cases of Meckel's diverticulum causing intestinal obstruction the diagnosis is rarely made pre-operatively. If an enterolith is present in the diverticulum it can sometimes be detected on plain abdominal X-ray. Meckel's is difficult to see on CT scan, but routine scanning during investigation of the obstruction may reveal a volvulus, intussusception or a true knot.⁵

Neoplasms are rare and the chances of detecting them on imaging are small. A large tumour will sometimes be seen on scintigraphy, CT scanning or barium studies.

Investigations are tailored to the requirements of the individual patient, and barium studies and ultrasonography are sometimes employed in all these situations to clarify equivocal findings or as less invasive investigations in paediatric patients.

For a symptomatic Meckel's diverticulum, laparoscopic resection has been shown to be safer, less invasive, and more cost-effective than laparotomy.⁵
There has been more controversy in the past about the management of an incidentally found asymptomatic diverticula. However, it is now generally agreed that it should be removed in patients under the age of 50.²