Meckel's diverticulum

Meckel's diverticulum
Diverticule de Meckel.jpg
Schematic drawing of a Meckel's diverticulum with a part of the small intestine.
SpecialtyMedical genetics Edit this on Wikidata

A Meckel's diverticulum, a true congenital diverticulum, is a slight bulge in the small intestine present at birth and a vestigial remnant of the omphalomesenteric duct (also called the vitelline duct or yolk stalk). It is the most common malformation of the 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 asymptomatic. An asymptomatic Meckel's diverticulum is called a silent Meckel's diverticulum.[4] If symptoms do occur, they typically appear before the age of two years.

The most common presenting symptom is painless rectal bleeding such as melaena-like black offensive stools, followed by intestinal obstruction, volvulus and intussusception. Occasionally, Meckel's diverticulitis may present with all the features of acute appendicitis. Also, severe pain in the epigastric region is experienced by the patient along with bloating in the epigastric and umbilical regions. At times, the symptoms are so painful that they may cause sleepless nights with acute pain felt in the foregut region, specifically in the epigastric and umbilical regions.

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.

Rarely, a Meckel's diverticulum containing ectopic pancreatic tissue can present with abdominal pain and increased serum amylase levels, mimicking acute pancreatitis.[5]

Complications

The lifetime risk for a person with Meckel's diverticulum to develop certain complications is about 4–6%. Gastrointestinal bleeding, peritonitis or intestinal obstruction may occur in 15–30% of symptomatic patients (Table 1). Only 6.4% of all complications requires surgical treatment; and untreated Meckel's diverticulum has a mortality rate of 2.5–15%.[6]

Table 1 – Complications of Meckel's Diverticulum:[7]

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.[8] Symptoms may include bright red blood in stools (hematochezia), weakness, abdominal tenderness or pain, and even anaemia in some cases.[9]

Hemorrhage 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.[10]
  3. Pain, bleeding or perforation of the bowel at the diverticulum may result.
  4. Mechanical stimulation may also cause erosion and ulceration.

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

  • Tarry stools: Alteration of blood produced by slow bowel transit due to minor bleeding in upper gastrointestinal tract
  • Bright red blood stools: Brisk haemorrhage
  • Stools with blood streak: Anal fissure
  • "Currant jelly" stools: Ischaemia of the intestine leads to copious mucus production and may indicate that one part of the bowel invaginates into another intussusception.

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.[12]

Diverticulitis may result from:

  • Association with the mesodiverticular band attaching to the diverticulum tip where torsion has occurred, causing inflammation and ischaemia.[13]
  • 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.[14]
  • Luminal obstruction due to tumors, enterolith, foreign body, causing stasis or bacterial infection.[15]
  • Association with acute appendicitis

Intestinal obstruction

Symptoms: Vomiting, abdominal pain and severe or complete constipation.[16]

  • 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).[15]
  • "Incarceration": when a Meckel's diverticulum is constricted in an inguinal hernia, forming a Littré hernia that obstructs the intestine.[17]
  • 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.[15]
  • 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.[7] 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[9]

Umbilical anomalies

Anomalies between the diverticulum and umbilicus may include the presence of fibrous cord, cyst, fistula or sinus, leading to:[12]

  • 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

Neoplasm

Tumors in Meckel's diverticulum may cause bleeding, acute abdominal pain, gastrointestinal obstruction, perforation or intussusception.[12]

  • Benign tumors:
  1. Leiomyoma
  2. Lipoma
  3. Vascular and neuromuscular hamartoma
  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[7]