Intussusception

Overview

Definition

Intussusception is telescoping of the proximal part (intussusceptum) into a distal part (intussuscipiens) of the intestine.

Epidemiology

• Incidence: 26–38 per every 100,000 live births
• Most common cause of bowel obstruction in the 6–36-month age group
• 60% of cases within 1st year of life
• Boys > girls (ratio of 3:2)
• Most prevalent around viral season

Etiology

• Idiopathic (75%–80% of cases) with no identifiable lead point:
  • Most common in children
  • Rare in adults
• Infection (causes Peyer’s patch enlargement):
  • Upper respiratory tract infection (30%)
  • Bacterial enteritis
  • Recent rotavirus immunization or infection
• Underlying pathology:
  • Meckel’s diverticulum (most common)
  • Henoch-Schönlein purpura (causes thickening of the mucosa)
  • Lymphoma
  • Intestinal polyps or tumors

Pathophysiology and Clinical Presentation

Pathophysiology

• Intussusception is considered idiopathic if it does not involve a lead point.
• Idiopathic intussusception is most common in the pediatric population.
• Lead point: a lesion that gets trapped during peristalsis, dragging that segment into the distal part of the intestine:
  • Tumor/polyp
  • Meckel’s diverticulum
  • Duplication cyst
  • Vascular malformation
  • Hematoma
• Pathologic lead point should be suspected if:
  • Multiple episodes of intussusception
  • In adults and children < 6 months or > 3 years of age
• Based on anatomic location, intussusception can be:
  • Ileocecal/ileocolic (most common, accounts for 85%–90% of cases)
  • Ileoileal
  • Ileocolic
  • Jejuno-ileal
  • Jejuno-jejunal
  • Colo-colic
• Telescoping of bowel into itself → obstruction and impaired lymphatic drainage
• Increasing pressure in intussusceptum bowel wall → impairment of venous and lymphatic drainage → vascular compromise
• Ischemia of intussusceptum mucosa → bowel mucosa infarcts and sloughs off → bloody stools
• Transmural necrosis and perforation may occur with prolonged ischemia

Clinical presentation

Toddlers/infants:

• Sudden onset, cramping, severe intermittent abdominal pain
• Drawing up legs toward abdomen
• Inconsolable crying
• Episodes occur every 15–20 minutes and become more frequent over time.
• Vomiting:
  • Non-bilious first
  • After a pain episode
  • Can become bilious as obstruction worsens
• Grossly bloody stool (50% of cases)
• Classic triad (only present in 15% of cases):
  • Abdominal pain
  • Sausage-shaped mass in the RUQ
  • Currant-jelly stool:
    • Blood mixed with mucus
    • Suggests mucosal necrosis and sloughing
    • Late presentation

Adults/older children:

• Intermittent abdominal pain is most common symptom.
• Other symptoms of bowel obstruction may occur:
  • Nausea/vomiting
  • Constipation
• Symptoms of underlying process (e.g., malignancy, infection):
  • Fever
  • Weight loss

Diagnosis

Pediatric intussusception

History:

• Episodes of crying, legs drawn toward abdomen
• Episodes of lethargy
• Bloody stools
• Vomiting
• Fever
• Sick contacts
• Potential food poisoning/toxin exposure

Physical exam:

• General appearance:
  • Pallor
  • Lethargy
• Palpation:
  • Sausage-shaped mass in the RUQ
  • Dance’s sign: scaphoid (empty) RLQ
  • May or may not have focal abdominal tenderness
  • Guarding, rebound: usually late signs associated with bowel ischemia
• Auscultation: high-pitched bowel sounds (indicative of obstruction)

Imaging:

• Abdominal ultrasound:
  • Best initial test
  • Target sign: the invaginated portion of the bowel appears as a ring on a target (outer bowel wall)
  • Pseudokidney sign: the appearance of the intussuscepted segment of bowel, which mimics a kidney
• Abdominal X-ray: 
  • Not very sensitive or specific test
  • Crescent sign: soft-tissue density projecting into colonic lumen
  • Signs of small bowel obstruction:
    • Dilated loop
    • Absence of gas in the colon
  • Pneumoperitoneum if perforation has occurred
• Abdominal CT: 
  • Performed only if other modalities yield unclear diagnosis
  • Usually identifies an underlying pathology (lead point) if present
• Contrast or pneumatic enema:
  • Confirmatory
  • Therapeutic as well as diagnostic for ileocecal intussusception
  • Performed using ultrasound or fluoroscopy
  • Procedure: Air/contrast is injected into the intestines to create pressure, which ejects the trapped part of the bowel out of the distal bowel.

Intussusception in adults

History:

• Will reveal symptoms of bowel obstruction
• Can be acute in onset or slow, insidious, and intermittent

Physical exam:

• Abdominal distention
• Focal or diffuse tenderness
• Peritonitis is a late presentation indicative of ischemia/perforation.

Imaging:

• Abdominal X-ray:
  • Nonspecific
  • Can show obstructive pattern:
    • Dilated small bowel loops
    • Paucity of colonic gas
    • Pneumoperitoneum if perforation occurred
• Abdominal CT scan:
  • Small bowel obstruction:
    • Dilated small bowel loops
    • Collapsed distal small bowel and colon
  • Bowel wall thickening
  • Target sign, sausage-shaped mass

Management

Pediatric intussusception

Initial management: 

• Nothing by mouth
• Nasogastric decompression
• Fluid resuscitation

Nonsurgical reduction:

• 1st-line therapy for:
  • Ileocecal intussusception
  • Stable patients without peritonitis/evidence of perforation/ischemia
• Accomplished with contrast or pneumatic enema
• Success rate: 80%–95% in experienced centers
• If reduction is partial, a repeat reduction can be attempted.
• Recurrence rate is 10%–20% (50% of those within first 72 hours).
• A repeat reduction can be performed for a stable patient.

Surgical management:

• Indications:
  • Unstable patient, peritonitis; evidence of perforation/ischemia
  • Completely unsuccessful reduction attempt with enema
  • A persistent filling defect after reduction, suggesting a tumor
  • For a small bowel-to-small bowel intussusception:
    • Some will resolve spontaneously.
    • If intussusception does not resolve, surgery is usually indicated.
    • Reduction with enema is usually unsuccessful.
    • Also, higher probability of a lead point/underlying pathology
• Procedures:
  • Hutchinson maneuver: 
    • Manual reduction of the intussusception
    • Bowel may appear edematous/inflamed, but if viable, does not need to be resected.
    • If there is no lead point identified, only manual reduction is needed.
    • Concomitant appendectomy is sometimes performed.
    • Can be performed open or laparoscopically
  • Bowel resection:
    • For bowel perforation
    • For nonviable bowel: permanent dullness or no detectable pulsation
    • Pathologic lead point identified (Meckel’s diverticulum, tumor)

Adult intussusception

General considerations:

• Asymptomatic intussusception without obstruction:
  • Usually an incidental finding on CT scan
  • Will resolve spontaneously and does not require an intervention
• Intussusception associated with bowel obstruction:
  • Usually associated with pathologic lead point (> 92% of cases)
  • Can involve small bowel or colon
  • Requires surgery
  • General approach is the same as for any bowel obstruction.

Initial/supportive management:

• Nothing by mouth
• Nasogastric decompression
• Intravenous fluids, electrolyte correction

Surgery:

• Procedure depends on underlying cause
• Usually involves bowel/pathologic lead point resection (tumor, Meckel’s diverticulum)

Differential Diagnosis

• Volvulus: small bowel obstruction secondary to intestinal malrotation in children. Patients have a similar presentation to intussusception, with vomiting and drawing in of the knees. Diagnosis can be established with ultrasound or upper GI series. This condition requires emergent surgery for bowel detorsion.
• Strangulated inguinal hernia: a nonreducible inguinal hernia containing a loop of bowel with compromised blood supply. Presents as irreducible inguinal mass that is usually tender and associated with symptoms of small bowel obstruction. Diagnosis is usually established with physical exam. Management involves emergent surgical hernia repair.
• Gastroenteritis: an acute viral infection of the GI tract that presents with diarrhea and abdominal pain. Watery diarrhea is usually a prominent feature, and diagnosis is established clinically. Management is usually supportive and involves oral or intravenous hydration.
• Colic: acute episodes of abdominal pain in infants associated with crying and irritability. Can be confused with intussusception, but the infant is healthy and thriving, with a normal exam.
• Appendicitis: acute inflammation of the appendix. In young children, presents with abdominal pain and crying spells. Right lower quadrant is usually exquisitely tender on physical exam with no palpable mass. Diagnosis is established based on exam and imaging studies, usually ultrasound in children. Management is appendectomy.