Meckel Diverticula in Adults

Meckel? Meckel‘s? Diverticula vs Diverticulum?
Let’s cover the easy part first – a diverticulUM is one single outpouching of a structure through its wall, a diverticulA is multiple diverticulum. On to the Meckel part: These diverticula were described by Johann Friedrich Meckel back in the 1800s. But possessive eponyms are falling out of favor for a number of reasons (check out this great article on EMRA).^​1​ We will be sticking to the style described in that article for the rest of this post and dropping the apostrophe and ‘s’ – Meckel diverticula.

The first time I learned about Meckel diverticula, they were just an interesting anecdote during an embryology lecture. This may be the first thing you think of when you hear the term, bringing up something about painless GI bleeding in children from the deep in your memory. I certainly wasn’t expecting to come across it, or a clinically significant complication from it in an an adult patient, but with more than 2% of the population affected, there are a few clinical contexts in which you should consider Meckel.

Background

Meckel diverticula are the most common congenital GI tract abnormality and are estimated to effect around 2% of the population.^​2–4​ They are a remnant of the omphalomesenteric duct which connects the yolk sack to the primitive gut in the developing embryo. In the usual embryonic development process, the duct will regress around week 5-7.^​5​ A Meckel’s diverticulum is a true diverticulum meaning it contains all layers of the bowel wall (mucosa, submucosa, muscularis and serosa). As a result of the development process, the mucosal cells in a Meckel diverticulum are pluripotent and can develop into a variety of different types of GI mucosa.^​5​ In around 50% of cases this is gastric mucosa, with pancreatic as the next most common, and colonic and other GI tissue types also possible.^​2,6​

Rule of 2’s and Complications

When learning about Meckel diverticula the “Rule of 2s” frequently come up – the diverticula are typically 2 inches long, 2 feet from the ileocecal valve, effect 2% of the population, and about 2% will become symptomatic.^​3,7​ Of this 2% that develop symptoms, around 50% will present before two years of age. Classically Meckel diverticula present as painless rectal bleeding in a young child. The bleeding results from acid production by heterotopic gastric mucosa. While this is the most common presentation in young children, there are several other potential complications of Meckel diverticula to be aware of that can occur at any age. The heterotopic mucosa can lead to ulceration and perforation. The diverticula can serve as a lead point for volvulus leading to intestinal obstruction; they can also involute on themselves and cause intussusception. Similar to an appendix, Meckel diverticula are blind ending pouches and have the potential to become blocked by enteroliths, leading to Meckel diverticulitis – inflammation and infection of these diverticula. Less common complications include malignant transformation of heterotopic tissue and herniation of the diverticulum (called a Littre hernia). If any adhesion remains from the diverticula to the abdominal wall, there are additional pathologies possible.^​7​

A number of risk factors have been identified for symptomatic Meckel diverticula and complications:

• Male sex
• Age > 50
• Diverticulum length >2 cm
• Presence of heterotopic mucosa

These risk factors are additive, with some studies citing up to 70% risk of complication for those with all four factors present.^​2​ Despite this risk, there is no consensus on whether or not incidentally found diverticula should be resected. 

Diagnostic Imaging

When a Meckel diverticulum is suspected there are two main imaging modalities that can be used:

• Techetium-99m scan
  • Use in the case of classic presentation (rectal bleeding in a child)/suspected heterotopic acid secretion
  • ~90% accurate
• CT scan
  • Use when presenting complication is obstruction/infection (differentiate appendicitis from Meckel diverticulitis)

Clinical Correlate

So, what happened with the Meckel case I encountered and did he read the textbook?

My patient was a 50s year old male who presented with right lower quadrant that was associated with fevers, chills, nausea and vomiting. CT imaging showed a 2 cm diverticulum with an enterolith and  surrounding inflammation located on the small bowel as well as a normal appendix. The patient initially opted for non-operative management but as his symptoms worsened, he agreed to undergo laparoscopic resection. The pathology report showed a perforated and inflamed diverticulum with heterotopic gastric mucosa. The patient did well post operatively and made a full recovery without complications. With 3 out of 4 risk factors present, this patient was truly a quintessential presentation of a Meckel diverticulum complication. 

Cite this post: Amelia Bryan, MD. “Meckel Diverticula in Adults”. GW EM Blog. 12/10/2024. Available at: https://gwemblog.com/meckel-diverticula-in-adults/

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