Meckel's diverticulum

 

Meckel's diverticulum

Meckel diverticulum is the most common congenital anomaly of the GI tract and is caused by the incomplete obliteration of the omphalomesenteric duct during the 7th wk of gestation.

Meckel diverticulum has been conveniently referred to by the “rule of 2s,”:

• Occurs in 2% of the population.
• Appears within 2 feet (50-75 cm) of the ileocecal valve.
• approximately 2 inches in length
• Approximately 2% to 4% of patients develop complications over the course of their lives.
• Typically presents before age 2 years.
• Two-thirds of patients with MD have 2 types of heterotopic mucosa (gastric and pancreatic), although colonic heterotopic mucosa has also been reported.
•  Is twice as likely to be symptomatic in boys than girls

Meckel diverticulum is typically lined by ileal mucosa.

Clinical presentations:

The majority are asymptomatic.

It is often found incidentally on imaging studies.

Hematochezia:

• Cause of bleeding is ectopic gastric mucosa (acid-secreting mucosa)
• Intermittent painless rectal bleeding (hematochezia) occurs suddenly and tends to be massive in younger patients.
• Bleeding occurs without prior warning and usually spontaneously subsides.
• The color of the stool is typically described as brick colored or currant jelly colored.
• Bleeding can cause significant anemia but is usually self-limited (resolves without intervention) because of contraction of the splanchnic vessels, as patients become hypovolemic.
• Bleeding from a Meckel diverticulum can also be less dramatic, with melanotic stools.

It should be suspected in children with recurrent or atypical intussusception, a patient with symptoms of appendicitis after their appendix has been removed, and patients with an unclear source of GI bleeding.

Physical signs:

• Tachycardia is an early clinical sign of hemorrhagic shock when severe bleeding episode occurs.
• Abdominal pain, bilious vomiting, generalized abdominal tenderness, distention, hypoactive or hyperactive bowel sounds, peritoneal signs, and rebound tenderness upon examination when intestinal obstruction occur.
• Signs of acute appendicitis in cases of diverticulitis.

Complications:

 Intestinal obstruction by two mechanisms:

• When the diverticulum acts as the lead point of an intussusception leading to intussusception
• when intraperitoneal bands connecting residual omphalomesenteric duct remnants to the ileum and umbilicus. These bands cause obstruction by internal herniation or volvulus of the small bowel around the band.

Occasionally becomes inflamed (diverticulitis) and manifests similarly to acute appendicitis. These children are older, with a mean of 8 yr of age. Diverticulitis can lead to perforation and peritonitis.

Differential Diagnoses

1.           Colitis

2.           Colonic Vascular Malformations

3.           Gastrointestinal Duplications

4.           Henoch-Schonlein Purpura (IgA Vasculitis)

5.           Intestinal Polyposis Syndromes

6.           Intussusception

7.           Juvenile Polyps

8.           Pediatric Appendicitis

9.           Pediatric Crohn Disease

10.        Pediatric Urolithiasis

11.        Peptic Ulcer Disease

12.        Peutz-Jeghers Syndrome

13.        Postoperative Adhesions

14.        Ulcerative Colitis in Children

15.        Volvulus

Work up:

Confirmation of a Meckel diverticulum can be difficult.

Plain abdominal radiographs are of no value, and routine barium studies rarely fill the diverticulum.

Technetium 99 scan or Meckel scan performed after intravenous infusion of technetium-99m pertechnetate, is the most commonly used modality for detecting heterotopic gastric mucosa associated with MD.

The uptake can be enhanced with various agents, including cimetidine, ranitidine, glucagon, and pentagastrin.

In children, the scan has a sensitivity of 85 percent and a specificity of 95 percent.

Because the Meckel scan is specific for gastric mucosa (ie, in the stomach or ectopic) and not specifically diagnostic of Meckel diverticulum, false-positive results occur whenever ectopic gastric mucosa is present. Duodenal ulcer, small intestinal obstruction, some intestinal duplications, ureteric obstruction, aneurysm, and angiomas of the small intestine have yielded positive results. False-negative results can occur when gastric mucosa is very slight or absent in the diverticulum, if necrosis of the diverticulum has occurred, or if the Meckel diverticulum is superimposed on the bladder.

• If a barium study is indicated, it should never precede the technetium-99m scan, because barium may obscure the hot spot.

Other methods of detection include radiolabeled tagged red blood cell scan (the patient must be actively bleeding).

Additional diagnostic evaluations, such as ultrasonography, computed tomographic scan, Magnetic resonance imaging (MRI) or superior mesenteric angiography may be considered.

Capsule endoscopy is a relatively new technology that assists with imaging in the small intestine. Wireless capsule endoscopy has been successfully used to identify Meckel diverticulum in young children and adolescents.

However, some infants with negative imaging and a high degree of suspicion may require exploratory laparotomy.

Management:

The treatment of a symptomatic Meckel diverticulum is surgical excision.

A diverticulectomy can be performed safely as either a laparoscopic or open procedure, although most continue to be performed as open procedures.

There is significant debate regarding the proper management of an asymptomatic Meckel diverticulum and whether excision vs observation is appropriate.

However, the risk of serious complications does seem to exceed the operative risk in children younger than 8 yr old.

References:

1. Melissa A. Kennedy, Asim Maqbool & Chris A. Liacouras : Remnants of the Omphalomesenteric Duct. In: Kliegman RM , Geme III JWS, Blum NJ, Shah SS,Tasker RC, Wilson KM, Behrman RE, editors. Nelson Textbook of Pediatrics. 21th ed. New Delhi: Elsevier; 2020. Chapter 357.2 ,Meckel Diverticulum and Other Remnants of the Omphalomesenteric Duct; 7763 - 7768.

2. Uppal K, Tubbs RS, Matusz P, Shaffer K, Loukas M. Meckel's diverticulum: a review. Clin Anat. 2011 May;24(4):416-22. 

3.Ruscher KA, Fisher JN, Hughes CD, Neff S, Lerer TJ, Hight DW, Bourque MD, Campbell BT. National trends in the surgical management of Meckel's diverticulum. J Pediatr Surg. 2011 May;46(5):893-6.