Meckel's diverticulum

Source: Wikipedia, the free encyclopedia.
Meckel's diverticulum
Schematic drawing of a Meckel's diverticulum with a part of the small intestine.
SpecialtyMedical genetics Edit this on Wikidata
Named afterJohann Friedrich Meckel

A Meckel's diverticulum, a true

gastrointestinal tract and is present in approximately 2% of the population,[1]
with males more frequently experiencing symptoms.

Meckel's diverticulum was first explained by

Fabricius Hildanus in the sixteenth century and later named after Johann Friedrich Meckel, who described the embryological origin of this type of diverticulum in 1809.[2][3]

Signs and symptoms

The majority of people with a Meckel's diverticulum are

epigastric and umbilical regions.[citation needed] In some cases, bleeding occurs without warning and may stop spontaneously. The symptoms can be extremely painful, often mistaken as just stomach pain resulting from not eating or constipation.[citation needed] Rarely, a Meckel's diverticulum containing ectopic pancreatic tissue can present with abdominal pain and increased serum amylase levels, mimicking acute pancreatitis.[7]

Complications

The lifetime risk for a person with Meckel's diverticulum to develop certain

Littre hernia. Only 6.4% of all complications require surgical treatment, and untreated Meckel's diverticulum has a mortality rate of 2.5–15%.[8]

Table 1 – Complications of Meckel's Diverticulum:[9]

Complications Percentage of symptomatic Meckel's Diverticulum (%)
Haemorrhage
 20–30
Intestinal obstruction
 20–25
Diverticulitis 10–20
Umbilical anomalies ≤10
Neoplasm 0.5-2

Bleeding

Bleeding of the diverticulum is most common in young children, especially in males who are less than 2 years of age.

anaemia in some cases.[11]

Bleeding may be caused by:

  • Ectopic gastric or pancreatic mucosa:
  1. Where diverticulum contains embryonic remnants of mucosa of other tissue types.
  2. Secretion of gastric acid or alkaline pancreatic juice from the ectopic mucosa leads to ulceration in the adjacent ileal mucosa i.e. peptic or pancreatic ulcer.[12]
  3. Pain, bleeding or perforation of the bowel at the diverticulum may result.
  4. Mechanical stimulation may also cause erosion and ulceration.
  • Gastrointestinal bleeding may be self-limiting but chronic bleeding may lead to
    iron deficiency anaemia.[13]

The appearance of stools may indicate the nature of the bleeding:

Diverticulitis

Inflammation of the diverticulum can mimic symptoms of appendicitis, i.e., periumbilical tenderness and intermittent crampy abdominal pain. Perforation of the inflamed diverticulum can result in peritonitis. Diverticulitis can also cause adhesions, leading to intestinal obstruction.[14]

Diverticulitis may result from:

  • Association with the mesodiverticular band attaching to the diverticulum tip where torsion has occurred, causing inflammation and ischaemia.[15]
  • Peptic ulceration resulting from ectopic gastric mucosa of the diverticulum
  • Following perforation by trauma or ingested foreign material e.g. stalk of vegetable, seeds or fish/chicken bone that become lodged in Meckel's diverticulum.[16]
  • Luminal obstruction due to
    tumors, enterolith, foreign body, causing stasis or bacterial infection.[17]
  • Association with acute appendicitis[6]

Intestinal obstruction

Symptoms: Vomiting, abdominal pain and severe or complete constipation.[18]

  • The vitelline vessels remnant that connects the diverticulum to the umbilicus may form a fibrous or twisting band (volvulus), trapping the small intestine and causing obstruction. Localised periumbilical pain may be experienced in the right lower quadrant (like appendicitis).[17]
  • "Incarceration": when a Meckel's diverticulum is constricted in an inguinal hernia, forming a Littré hernia that obstructs the intestine.[19]
  • Chronic diverticulitis causing stricture
  • Strangulation of the diverticulum in the obturator foramen.
  • Tumors e.g. carcinoma: direct spread of an adenocarcinoma arising in the diverticulum may lead to obstruction
  • Lithiasis
    , stones that are formed in Meckel's diverticulum can:
  1. Extrude into the terminal ileum, leading to obstruction
  2. Induce local inflammation and intussusception.[17]
  • The diverticulum itself or tumour within it may cause intussusception. For example, from the ileum to the colon, causing obstruction. Symptoms of this include "currant jelly" stools and a palpable lump in the lower abdomen.[9] This occurs when the diverticulum inverts into the lumen of the ileum, due to either:
  1. An active peristaltic mechanism of the diverticulum that attempts to remove irritating factors
  2. A passive process such as the transit of food[11]

Umbilical anomalies

Anomalies between the diverticulum and umbilicus may include the presence of fibrous cord, cyst, fistula, or sinus, leading to:[14]

  • Infection or excoriation of periumbilical skin, resulting in a discharging sinus
  • Recurrent infection and healing of sinus
  • Abscess formation in the abdominal wall
  • Fibrous cord increases the risk of volvulus formation and internal herniation

Tumors

Neoplasms (tumors) in Meckel's diverticulum may cause bleeding, acute abdominal pain, gastrointestinal obstruction, perforation or intussusception. They may be benign or malignant.[14]

  • Benign tumors:
  1. Leiomyoma
  2. Lipoma
  3. Vascular and
    neuromuscular hamartoma
  • Malignant tumors:
  1. Carcinoids: most common, 44%
  2. Mesenchymal tumors: Leiomyosarcoma, peripheral nerve sheath and gastrointestinal stromal tumors
    , 35%
  3. Adenocarcinoma, 16%
  4. Desmoplastic
    small round cell tumor

Other complications

  • A diverticulum inside a Meckel's diverticulum (daughter diverticula)
  • Stones and phytobezoar (a bezoar of vegetable fibers) in Meckel's diverticulum
  • Vesicodiverticular fistula[9]

Pathophysiology

Meckel's diverticulum surgical specimen

The omphalomesenteric duct (omphaloenteric duct, vitelline duct, or yolk stalk) normally connects the embryonic midgut to the yolk sac ventrally, providing nutrients to the midgut during embryonic development. The vitelline duct narrows progressively and disappears between the 5th and 8th weeks of gestation.[citation needed]

In Meckel's diverticulum, the proximal part of vitelline duct fails to regress and involute, which remains as a remnant of variable length and location.[16] The solitary diverticulum lies on the antimesenteric border of the ileum (opposite to the mesenteric attachment) and extends into the umbilical cord of the embryo.[8] The left and right vitelline arteries originate from the primitive dorsal aorta, and travel with the vitelline duct. The right becomes the superior mesenteric artery that supplies a terminal branch to the diverticulum, while the left involutes.[17] Having its own blood supply, Meckel's diverticulum is susceptible to obstruction or infection.

Meckel's diverticulum is located in the

muscularis propria.[17]

As the vitelline duct is made up of

pancreatic tissue are seen in 60% and 6% of cases respectively. Heterotopic means the displacement of an organ from its normal anatomic location.[21] Inflammation of this Meckel's diverticulum may mimic appendicitis. Therefore, during appendectomy, ileum should be checked for the presence of Meckel's diverticulum, if it is found to be present it should be removed along with appendix.[citation needed
]

A memory aid is the rule of 2s:[22]

  • 2% (of the population)
  • 2 feet (proximal to the ileocecal valve)
  • 2 inches (in length)
  • 2 types of common ectopic tissue (gastric and pancreatic)
  • 2 years is the most common age at clinical presentation
  • 2:1 male:female ratio

However, the exact values for the above criteria range from 0.2–5 (for example, prevalence is probably 0.2–4%).[citation needed]

It can also be present as an indirect hernia, typically on the right side, where it is known as a "Hernia of Littré". A case report of strangulated umbilical hernia with Meckel's diverticulum has also been published in the literature.[23] Furthermore, it can be attached to the umbilical region by the vitelline ligament, with the possibility of vitelline cysts, or even a patent vitelline canal forming a vitelline fistula when the umbilical cord is cut. Torsions of intestine around the intestinal stalk may also occur, leading to obstruction, ischemia, and necrosis.

Diagnosis

Technetium-99m Pertechnetate Scan with a Meckel's Diverticulum.

A

noninvasive, with 95% specificity and 85% sensitivity;[17] however, in adults the test is only 9% specific and 62% sensitive.[25] This scan is more accurate in children because gastric mucosa is found in 90% of bleeding diverticula; which is the most common symptom in children, not adults. [26]

Patients with these misplaced gastric cells may experience

bleeding disorders should be performed, and angiography can assist in determining the location and severity of bleeding. Colonoscopy might be helpful to rule out other sources of bleeding but it is not used as an identification tool.[citation needed]

Angiography of a Meckel's diverticulum that presented with bleeding.

Angiography might identify brisk bleeding in patients with Meckel's diverticulum.[17]

Computed tomography (CT scan) might be a useful tool to demonstrate a blind ended and inflamed structure in the mid-abdominal cavity, which is not an appendix.[17]

In asymptomatic patients, Meckel's diverticulum is often diagnosed as an incidental finding during laparoscopy or laparotomy.[citation needed]

Treatment

Treatment is surgical, potentially with a laparoscopic

diverticulectomy.[17]

With regards to asymptomatic Meckel's diverticulum, some recommend that a search for Meckel's diverticulum should be conducted in every case of appendectomy/laparotomy done for acute abdomen, and if found, Meckel's diverticulectomy or resection should be performed to avoid secondary complications arising from it.[28]

Epidemiology

Meckel's diverticulum occurs in about 2% of the population.[21] Prevalence in males is 3–5 times higher than in females.[20] Only 2% of cases are symptomatic, which usually presents among children at the age of 2.[8]

Most cases of Meckel's diverticulum are diagnosed when complications manifest or incidentally in unrelated conditions such as laparotomy, laparoscopy or contrast study of the small intestine. Classic presentation in adults includes intestinal obstruction and inflammation of the diverticulum (diverticulitis). Painless rectal bleeding most commonly occurs in toddlers.[5]

Inflammation in the ileal diverticulum has symptoms that mimic appendicitis, therefore its diagnosis is of clinical importance. Detailed knowledge of the pathophysiological properties is essential in dealing with the life-threatening complications of Meckel's diverticulum.[17]

References

  1. S2CID 45677981
    .
  2. Who Named It?
  3. ^ J. F. Meckel. Über die Divertikel am Darmkanal. Archiv für die Physiologie, Halle, 1809, 9: 421–453.
  4. PMID 19103339
    .
  5. ^ a b "Meckel's Diverticulum". The Lecturio Medical Concept Library. Retrieved 10 August 2021.
  6. ^ a b "Appendicitis (Differential Diagnosis)". The Lecturio Medical Concept Library. Retrieved 1 July 2021.
  7. ^ Darlington CD, Anitha GF. Meckel's diverticulitis masquerading as acute pancreatitis: A diagnostic dilemma. Archived 2018-06-02 at the Wayback Machine Indian Journal of Critical Care Medicine 2017; 21:789‑92.
  8. ^ a b c Schoenwolf, G. C., & Larsen, W. J. (2009). Larsen's human embryology (4th ed.). Philadelphia: Churchill Livingstone/Elsevier.
  9. ^
    S2CID 29734423
    .
  10. PMID 17021300
    .
  11. ^
    S2CID 33255331
    .
  12. PMID 11813588
    .
  13. PMID 12424418
    .
  14. ^
    PMID 18700974
    .
  15. ^ Tan, Y. M., & Zheng, Z. X. (2005). Recurrent torsion of a giant Meckel's diverticulum. Digestive Diseases and Sciences, 50(7), 1285–1287.
  16. ^ a b Drake, R. L., Vogl, W., Mitchell, A. W. M., Gray, H., & Gray, H. (2010). Gray's anatomy for students (2nd ed.). Philadelphia, PA: Churchill Livingstone/Elsevier.
  17. ^ a b c d e f g h i j k l Mattei, P. (2011). Fundamentals of Pediatric Surgery. New York, NY: Springer Science+Business Media, LLC.
  18. ^ Pariza, G., Mavrodin, C. I., & Ciurea, M. (2009). Complicated meckel's diverticulum in adult pathology. [Diverticulul Meckel complicat in patologia adultului] Chirurgia (Bucharest, Romania : 1990), 104(6), 745–748.
  19. ^ Martin, E. (2010). Concise colour medical dictionary (5th ed.) Oxford University Press.
  20. ^ a b Moore, K. L., Persaud, T. V. N., & Torchia, M. G. (2013). The developing human: Clinically oriented embryology (9th ed.). Philadelphia: Elsevier/Saunders.
  21. ^ a b Robbins, S. L., Kumar, V., & Cotran, R. S. (2010). Robbins and Cotran pathologic basis of disease (8th ed.). Philadelphia, PA: Saunders/Elsevier
  22. ^ F. Charles Brunicardi, Dana K. Anderson, Timothy R. Billiar, et al. Small Intestine. In: Ali Tavakkoli, Stanley W. Ashley, Michael J. Zinner: Schwartz's Principles of Surgery. 10 ed. United states: McGraw-Hill;2015
  23. PMID 16807577
    .
  24. PMID 10706156. Archived from the original
    on 2011-06-06. Retrieved 2009-03-03.
  25. S2CID 41285839
    .
  26. ^ Malik AA; Shams-ul-Bari, Wani KA, Khaja AR. Meckel's diverticulum-Revisited. Saudi J Gastroenterol. 2010 Jan-Mar;16(1):3-7. doi: 10.4103/1319-3767.58760. PMID: 20065566; PMCID: PMC3023098.
  27. PMID 22764670
    .
  28. PMID 20616416
    .

External links
Wikimedia Commons has media related to Meckel's diverticulum.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Meckel%27s_diverticulum&oldid=1216709156"