Background

Meckel diverticulum is a congenital abnormality of the small intestine and is the most common cause of significant lower gastrointestinal bleeding in children. It arises from incomplete involution of the vitelline duct during embryonic development, typically occurring by the 7th week of gestation. It is characterized by a blind-ending true diverticulum that contains all the layers found in the ileum.

Courtesy of Emma Gevorgyan, Radiopaedia.org, rID: 158581

Especially relevant to Board exams – Meckel’s Diverticulum follows the rule of 2’s:

  • It affects approximately 2% of the population
  • It is located about 2 feet from the ileocecal valve
  • It is usually around 2 inches long
  • About 2% of cases become symptomatic
  • It is most commonly diagnosed by the age of 2 years, with 45% of symptomatic cases occurring in this age group
  • It is twice as common in boys
  • There are two types of epithelium found in Meckel’s diverticulum – gastric and pancreatic

Presentation

The clinical presentation of Meckel’s diverticulum can vary depending on the complications that arise. The most common presentation in children under 5 years of age is rectal bleeding, which may be intermittent or massive. The bleeding is usually painless. Other complications include obstruction due to intussusception or volvulus, leading to bowel ischemia and shock. Diverticulitis and umbilical fistula can also occur. In approximately one-third of cases, Meckel’s diverticulum may perforate, and traumatic rupture can occur following blunt trauma.

Differential Diagnosis

The differential diagnosis for lower gastrointestinal bleeding includes:

  • Upper gastrointestinal bleeding
    • Generally lower GI bleeding is bright red (hematochezia) upper is melon (dark maroon to black) but very brisk upper GI bleeding can still be red
  • Diverticular disease (diverticulosis and diverticulitis) – which is rare in children
  • Vascular ectasia or angiodysplasia
  • Inflammatory bowel disease
  • Infectious colitis
  • Mesenteric ischemia or ischemic colitis
  • Colorectal cancer or polyps
  • Hemorrhoids (internal or external)
  • Aortoenteric fistula – rare in children, can be a complication of inflammatory bowel disease or previous vascular surgery
  • Rectal foreign body
  • Rectal ulcer (associated with HIV, syphilis, or STIs)
  • Anal fissure

Diagnosis

The Meckel’s scan – a technetium-99m pertechnetate scan, is the classic test of choice for diagnosis. This nuclear medicine scan utilizes a radioactive tracer that is taken up by the gastric mucosa in Meckel’s diverticulum, thereby helping to identify its presence. The sensitivity is reported to be about 60% in adults but 85-90% in children. The uptake of the dye can be increased by giving cimetidine or glucagon. The feeding artery of the Meckel diverticulum is an anomalous superior mesenteric artery branch. It has a long and non-branching course and ends toward the right lower quadrant. Ultrasound and CT may not differentiate it from normal bowel.

Case courtesy of Yusra Sheikh, Radiopaedia.org, rID: 44734

Management

In the ED the following steps should be taken:

  • Insertion of a nasogastric tube (NGT) for decompression if the patient has signs of obstruction
  • Administration of broad-spectrum antibiotics to cover potential bacterial infection
  • Intravenous fluids (IVF) to maintain hydration and electrolyte balance or to resuscitate
  • Order a CBC and Type and Screen
  • Packed red blood cells (pRBCs) as needed to address significant bleeding
  • Consultation with a surgical specialist to evaluate the need for surgical intervention

In cases of symptomatic Meckel’s diverticulum with complications such as significant bleeding, bowel obstruction, or perforation, emergent surgical removal of the diverticulum is typically warranted. This can be done via a laparoscopic or open approach.

“Clinically, Meckel diverticulum should be suspected in any child younger than 2 years of age with painless rectal bleeding.
It accounts for approximately 50% of all lower GI bleeding in children younger than 2 years of age.”

An et. al., STAT Pearls, 2023

Wrap Up

Meckel diverticulum is a congenital anomaly of the small intestine that can present with various clinical manifestations, including rectal bleeding and obstruction. Recognizing the characteristic features and understanding the differential diagnosis is crucial in managing patients with lower gastrointestinal bleeding. The Meckel’s scan is the preferred diagnostic modality, and prompt surgical consultation may be necessary for symptomatic cases.

References

Dixon P & Nolan D. The Diagnosis of Meckel’s Diverticulum: A Continuing Challenge. Clin Radiol. 1987;38(6):615-9

Ghahremani G. Radiology of Meckel’s Diverticulum. Crit Rev Diagn Imaging. 1986;26(1):1-43

Weerakkody Y, Ranchod A, Yap J, et al. Meckel diverticulum. Reference article, Radiopaedia.org (Accessed on 26 Oct 2023) https://doi.org/10.53347/rID-17174

Sagar J, Kumar V, Shah DK. Meckel’s diverticulum: a systematic review. J R Soc Med. 2006 Oct;99(10):501-5.

An J, Zabbo CP. Meckel Diverticulum. [Updated 2023 Jan 30]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK499960/#