Meckel’s Diverticulum

Overview

Definition

A Meckel’s diverticulum is a persistent remnant of the omphalomesenteric duct. A Meckel’s diverticulum is a true diverticulum (contains all layers of the bowel wall), arising from the antimesenteric surface of the middle-to-distal ileum.

Epidemiology

• The most common congenital gastrointestinal (GI) tract anomaly 
• Prevalence: approximately 2% of the population
• Sex: males > females (2:1)
• Most commonly presents with symptoms at 2–4 years of age
• Increased incidence in children with major malformations involving the:
  • Umbilicus
  • GI tract
  • Nervous system Nervous system The nervous system is a small and complex system that consists of an intricate network of neural cells (or neurons) and even more glial cells (for support and insulation). It is divided according to its anatomical components as well as its functional characteristics. The brain and spinal cord are referred to as the central nervous system, and the branches of nerves from these structures are referred to as the peripheral nervous system. General Structure of the Nervous System
  • Heart

Rule of 2(s)

• 2% of population
• 2 times more common in males
• Frequently presents by 2 years of age
• 2% develop symptoms/complications
• 2 inches long
• 2 feet from the ileocecal valve

Etiology

• Omphalomesenteric duct:
  • Connects the midgut to the yolk sac in utero
  • Normally involutes between the 5th and 6th weeks of gestation
• Omphalomesenteric duct that does not fully involute can give rise to:
  • A Meckel’s diverticulum (most common persistent remnant)
  • Omphalomesenteric cysts
  • Omphalomesenteric fistula (drain through umbilicus)
  • Fibrous bands (can cause bowel obstruction)

Pathophysiology and Clinical Presentation

Anatomy

• True diverticulum: contains all histologic layers of the intestinal tract
• Located in the middle to distal ileum (2 feet from the ileocecal valve)  
• Usually arises from the antimesenteric surface
• Mucosal lining:
  • Resembles a normal small intestine Small intestine The small intestine is the longest part of the GI tract, extending from the pyloric orifice of the stomach to the ileocecal junction. The small intestine is the major organ responsible for chemical digestion and absorption of nutrients. It is divided into 3 segments: the duodenum, the jejunum, and the ileum. Small Intestine
  • But may contain ectopic (heterotopic) mucosa (12%–44%):
    • Gastric (most common)
    • Pancreatic
    • Colonic
• Blood supply: vitelline artery (a branch of the superior mesenteric artery)

Pathophysiology

• GI bleeding:
  • Occurs if a Meckel’s diverticulum contains ectopic gastric mucosa
  • Gastric mucosa secretes acid and ulceration occurs → ulceration is downstream or in the adjacent small bowel mucosa → bleeding
• Meckel’s diverticulitis:
  • Acute inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body's defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation of a Meckel’s diverticulum (similar to appendicitis Appendicitis Appendicitis is the acute inflammation of the vermiform appendix and the most common abdominal surgical emergency globally. The condition has a lifetime risk of 8%. Characteristic features include periumbilical abdominal pain that migrates to the right lower quadrant, fever, anorexia, nausea, and vomiting. Appendicitis)
  • Diverticular opening becomes obstructed (fecalith, food, foreign body, tumor), leading to bacterial overgrowth and inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body's defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation.
  • May result in ischemia and perforation in severe cases
• Small bowel obstruction ( SBO SBO Small bowel obstruction (SBO) is an interruption of the flow of the intraluminal contents through the small intestine, and is classified as mechanical (due to physical blockage) or functional (due to disruption of normal motility). The most common cause of SBO in the Western countries is post-surgical adhesions. Small bowel obstruction typically presents with nausea, vomiting, abdominal pain, distention, constipation, and/or obstipation. Small Bowel Obstruction) may result from several mechanisms:
  • Intussusception Intussusception Intussusception occurs when a part of the intestine (intussusceptum) telescopes into another part (intussuscipiens) of the intestine. The condition can cause obstruction and, if untreated, progress to bowel ischemia. Intussusception is most common in the pediatric population, but is occasionally encountered in adults. Intussusception:
    • Part of the bowel telescopes into itself.
    • A Meckel’s diverticulum acts as a lead point.
  • Volvulus Volvulus A volvulus is the twisting or axial rotation of a portion of the bowel around its mesentery. The most common site of volvulus in adults is the colon; most frequently the sigmoid volvulus. Patients typically present with symptoms of bowel obstruction such as abdominal pain, distension, vomiting, and constipation/obstipation. Volvulus:
    • A Meckel’s diverticulum sometimes has fibrous bands connecting to the peritoneum Peritoneum The peritoneum is a serous membrane lining the abdominopelvic cavity. This lining is formed by connective tissue and originates from the mesoderm. The membrane lines both the abdominal walls (as parietal peritoneum) and all of the visceral organs (as visceral peritoneum). Peritoneum and Retroperitoneum/abdominal wall.
    • Intestines can twist around the fibrous bands.
  • Torsion: twisting of the diverticulum itself
  • Meckel’s diverticulitis: Inflammation can narrow the lumen of the adjacent small bowel.
  • Littre’s hernia: The diverticulum becomes incarcerated into a hernia.
  • Inversion: The diverticulum inverts into a bowel lumen and causes intermittent obstruction.

Clinical presentation

• Frequently clinically silent
• 25%–50% of symptomatic patients are < 10 years of age.
• In adults (especially < 40 years of age): A Meckel’s diverticulum is suspected if there is no identifiable source of GI bleeding.
• Presentation similar in children and adults: 
  • Painless lower GI bleeding (most common):
    • Acute (massive hematochezia)
    • Chronic/slow (melena; currant jelly or maroon stools in children)
  • SBO SBO Small bowel obstruction (SBO) is an interruption of the flow of the intraluminal contents through the small intestine, and is classified as mechanical (due to physical blockage) or functional (due to disruption of normal motility). The most common cause of SBO in the Western countries is post-surgical adhesions. Small bowel obstruction typically presents with nausea, vomiting, abdominal pain, distention, constipation, and/or obstipation. Small Bowel Obstruction:
    • Nausea/vomiting
    • Cramping abdominal pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain
    • Abdominal distention
    • In children: most commonly in the form of recurrent intussusception
  • Meckel’s diverticulitis:
    • Symptoms similar to acute appendicitis Appendicitis Appendicitis is the acute inflammation of the vermiform appendix and the most common abdominal surgical emergency globally. The condition has a lifetime risk of 8%. Characteristic features include periumbilical abdominal pain that migrates to the right lower quadrant, fever, anorexia, nausea, and vomiting. Appendicitis
    • With signs of peritoneal irritation if perforated
    • Abdominal tenderness is usually more midline.

Diagnosis

Tests for GI bleeding

• Radiology:
  • Meckel’s scan:
    • Used as a 1st-line test in hemodynamically stable patients and if suspicion is high (usually children)
    • Nuclear medicine scan utilizing radioactively labeled technetium that binds to gastric mucosa
    • Ectopic gastric mucosa is identified on scintigraphy.
  • Arteriography:
    • If the bleeding is brisk enough to necessitate blood transfusion
    • An anomalous branch of the superior mesenteric artery feeding the Meckel’s diverticulum can be identified.
    • Invasive test
  • Computed tomography (CT) angiography:
    • More sensitive than arteriography for less-brisk hemorrhage
    • Detects slow bleeding (0.3 mL/min)
• Endoscopy:
  • Capsule endoscopy: can visualize a normal, bleeding, inverted, and ulcerated Meckel’s diverticulum
  • Double-balloon enteroscopy:
    • Confirms diagnosis and complications by visualization
    • Enteroscope can be passed via the mouth into the small bowel, or by retrograde fashion, through the colon Colon The large intestines constitute the last portion of the digestive system. The large intestine consists of the cecum, appendix, colon (with ascending, transverse, descending, and sigmoid segments), rectum, and anal canal. The primary function of the colon is to remove water and compact the stool prior to expulsion from the body via the rectum and anal canal. Colon, Cecum, and Appendix.
    • Requires specialized skills and longer time

Tests for SBO SBO Small bowel obstruction (SBO) is an interruption of the flow of the intraluminal contents through the small intestine, and is classified as mechanical (due to physical blockage) or functional (due to disruption of normal motility). The most common cause of SBO in the Western countries is post-surgical adhesions. Small bowel obstruction typically presents with nausea, vomiting, abdominal pain, distention, constipation, and/or obstipation. Small Bowel Obstruction and diverticulitis

• CT scan:
  • Will identify SBO SBO Small bowel obstruction (SBO) is an interruption of the flow of the intraluminal contents through the small intestine, and is classified as mechanical (due to physical blockage) or functional (due to disruption of normal motility). The most common cause of SBO in the Western countries is post-surgical adhesions. Small bowel obstruction typically presents with nausea, vomiting, abdominal pain, distention, constipation, and/or obstipation. Small Bowel Obstruction, inflammatory changes, perforation
  • A Meckel’s diverticulum itself is diagnosed correctly in about 50%.
• Diagnostic laparoscopy Laparoscopy Laparoscopy is surgical exploration and interventions performed through small incisions with a camera and long instruments. Laparotomy and Laparoscopy:
  • Performed if imaging studies are equivocal (difficult to distinguish an inflamed diverticulum from appendicitis Appendicitis Appendicitis is the acute inflammation of the vermiform appendix and the most common abdominal surgical emergency globally. The condition has a lifetime risk of 8%. Characteristic features include periumbilical abdominal pain that migrates to the right lower quadrant, fever, anorexia, nausea, and vomiting. Appendicitis on imaging)
  • Can be therapeutic as well as diagnostic

Management

Asymptomatic

• A Meckel’s diverticulum incidentally found on imaging: no treatment necessary
• A Meckel’s diverticulum found during surgery (for another condition):
  • Considerations:
    • Clinical status (higher perioperative risk in older patients)
    • Life-long risk of complications (higher in children)
    • Diverticular abnormalities or features (that increase the risk of complications)
  • Resection recommended:
    • In children 
    • In healthy (< 50 years of age) adults: if a Meckel’s diverticulum is > 2 cm long or palpable abnormalities/fibrous bands are noted
    • In patients > 50 years of age or with comorbidities: if there is a palpable abnormality (heterotopic mucosa, possible tumor, fibrous bands)
  • No resection recommended: if patient is > 50 years of age and there is no palpable abnormality
• Counseling should be provided regarding possible future symptoms.

Symptomatic

• Supportive:
  • Intravenous hydration and resuscitation
  • Blood transfusion if necessary (for GI bleeding)
  • Bowel rest, nasogastric decompression (for SBO SBO Small bowel obstruction (SBO) is an interruption of the flow of the intraluminal contents through the small intestine, and is classified as mechanical (due to physical blockage) or functional (due to disruption of normal motility). The most common cause of SBO in the Western countries is post-surgical adhesions. Small bowel obstruction typically presents with nausea, vomiting, abdominal pain, distention, constipation, and/or obstipation. Small Bowel Obstruction)
  • Intravenous antibiotics (for Meckel’s diverticulitis)
• Surgery (definitive treatment):
  • Emergent if signs of sepsis Sepsis Organ dysfunction resulting from a dysregulated systemic host response to infection separates sepsis from uncomplicated infection. The etiology is mainly bacterial and pneumonia is the most common known source. Patients commonly present with fever, tachycardia, tachypnea, hypotension, and/or altered mentation. Sepsis and Septic Shock, peritonitis, perforation
  • Resection of a Meckel’s diverticulum
  • Segmental small bowel resection (including a Meckel’s diverticulum):
    • To include ulcerated bleeding mucosa
    • If the adjacent small bowel is severely inflamed/ischemic

Differential Diagnosis

• Acute appendicitis Appendicitis Appendicitis is the acute inflammation of the vermiform appendix and the most common abdominal surgical emergency globally. The condition has a lifetime risk of 8%. Characteristic features include periumbilical abdominal pain that migrates to the right lower quadrant, fever, anorexia, nausea, and vomiting. Appendicitis: presents with abdominal pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain and tenderness mostly in the right lower quadrant. A CT scan can help differentiate between a Meckel’s diverticulum and appendicitis Appendicitis Appendicitis is the acute inflammation of the vermiform appendix and the most common abdominal surgical emergency globally. The condition has a lifetime risk of 8%. Characteristic features include periumbilical abdominal pain that migrates to the right lower quadrant, fever, anorexia, nausea, and vomiting. Appendicitis, but not with 100% accuracy. Sometimes the definitive diagnosis is only made at surgery.
• Intussusception Intussusception Intussusception occurs when a part of the intestine (intussusceptum) telescopes into another part (intussuscipiens) of the intestine. The condition can cause obstruction and, if untreated, progress to bowel ischemia. Intussusception is most common in the pediatric population, but is occasionally encountered in adults. Intussusception due to other causes: in infants and toddlers, classically presents as intermittent colicky abdominal pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain with currant jelly stools. Adults and older children present with symptoms of bowel obstruction. Intussusception Intussusception Intussusception occurs when a part of the intestine (intussusceptum) telescopes into another part (intussuscipiens) of the intestine. The condition can cause obstruction and, if untreated, progress to bowel ischemia. Intussusception is most common in the pediatric population, but is occasionally encountered in adults. Intussusception in young children is often idiopathic, but in adults, intussusception is frequently associated with tumors.
• Volvulus Volvulus A volvulus is the twisting or axial rotation of a portion of the bowel around its mesentery. The most common site of volvulus in adults is the colon; most frequently the sigmoid volvulus. Patients typically present with symptoms of bowel obstruction such as abdominal pain, distension, vomiting, and constipation/obstipation. Volvulus (due to malrotation): congenital condition that usually manifests in infancy, but sometimes not until adulthood. Twisting of the mesentery results in intestinal ischemia Intestinal ischemia Intestinal ischemia occurs when perfusion fails to meet the demands of the intestines, resulting in ischemic tissue injury that can be life-threatening if bowel necrosis and/or perforation occurs. Symptoms can range from mild indigestion or diarrhea to severe abdominal pain. Intestinal Ischemia. A volvulus presents with severe abdominal pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain and bloody stools in advanced cases. A volvulus requires emergent surgery.
• Colonic diverticulosis and arteriovenous (AV) malformations: most common causes of painless lower GI bleeding in older adults. Colonic diverticulosis and AV malformations can present with acute (hematochezia) or chronic slow bleeding (melena). Diagnosis is usually established by colonoscopy or angiography (in actively bleeding AV malformations).