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 100 cm of the ileocecal valve.¹

Epidemiology

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

Presentation³

Asymptomatic

Meckel's diverticulum 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 more common in children younger than 2 years and in males.The patient usually reports bright red blood in the stools. The amount may vary from minimal recurrent episodes to a large shock-producing haemorrhage. Meckel's diverticulum 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 right iliac fossa can mimic appendicitis ('Meckel's diverticulitis'). Various mechanisms produce the obstruction, including a fibrotic band attaching the diverticula to the abdominal wall 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 or 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).

Diverticular inflammation sometimes occurs (10-20% of symptomatic patients), particularly in the elderly . Such diverticulitis can lead to diarrhoea, abdominal cramps and periumbilical tenderness.

Investigations³

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 preoperatively. If an enterolith is present in the diverticulum it can sometimes be detected on plain abdominal X-ray. Meckel's diverticulum 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.

One study reported the use of wireless capsule endoscopy to detect Meckel's diverticulum in children.⁶

Management³

Complications such as haemorrhage, diverticulitis, intestinal obstruction and umbilico-ileal fistulas are absolute indications for resection.

In asymptomatic individuals, resection of a diverticulum discovered incidentally should be considered for:

• Patients aged younger than 40.
• Diverticula longer than 2 cm.
• Diverticula with narrow necks.
• Diverticula with fibrous bands.
• Suspected ectopic gastric tissue.
• Inflamed, thickened diverticula.

For a symptomatic Meckel's diverticulum, laparoscopic resection has been shown to be safer, less invasive and more cost-effective than laparotomy.⁵

Postoperative complications

These are not uncommon. 10-12% of asymptomatic patients develop early complications such as ileus, suture line or intestinal anastomotic leak, intra-abdominal abscess or pulmonary embolism.

Late postoperative complications (6-8% of patients) develop intestinal adhesions leading to small bowel obstruction.

Prognosis³

One study found that the lifetime risk of complications from Meckel's diverticulum is 4.2%. The mortality rate for symptomatic patients treated surgically is 2-5%.

History^3,7

In 1809, Johann Friedrich Meckel published a paper concerning a diverticular remnant of the omphalomesenteric duct sited at the ileum. The document was quite detailed and included a description of the anatomy and embryonic origin. It thus came to be known by his name, although it was first described as an unusual diverticulum of the small intestine by Fabricius Hildanus in 1598.

Document references

1. Diagram of Meckel's Diverticulum; Health.allrefer.com
2. McKay R; High incidence of symptomatic Meckel's diverticulum in patients less than fifty years of age: an indication for resection. Am Surg. 2007 Mar;73(3):271-5. [abstract]
3. Kuwajerwala NK; Meckel Diverticulum, eMedicine, Aug 2008
4. Alenizi EK, Alfeeli MA; Intestinal duplication mimicking meckel diverticulum. Clin Nucl Med. 2008 Mar;33(3):189-90. [abstract]
5. Levy AD, Hobbs CM; From the archives of the AFIP. Meckel diverticulum: radiologic features with pathologic Correlation. Radiographics. 2004 Mar-Apr;24(2):565-87. [abstract]
6. Fritscher-Ravens A, Scherbakov P, Bufler P, et al; The feasibility of wireless capsule endoscopy in detecting small intestinal Gut. 2009 Nov;58(11):1467-72. Epub 2009 Jul 21. [abstract]
7. Meckel's diverticulum; whonamedit.com 2010

Internet and further reading

• Malik AA, Wani KA, Khaja AR; Meckel's diverticulum-Revisited. Saudi J Gastroenterol. 2010 Jan-Mar;16(1):3-7. [abstract]

Acknowledgements