Intussusception

Detailed Overview

It is the most common cause of intestinal obstruction in children between 6 and 36 months of age. The invagination drags the mesentery along with it, leading to venous congestion, bowel wall edema, subsequent arterial compromise, and if untreated, bowel necrosis and perforation. The most common site is the ileocecal junction.

Epidemiology & Demographics

Incidence is 1 to 4 in 1,000 live births. Peak age is 5 to 9 months. It is more common in males (ratio 3:1).

Etiological Mechanism

In 90% of pediatric cases, it is idiopathic, commonly associated with hypertrophied Peyer's patches following a viral illness (adenovirus, rotavirus). In adults, a pathological lead point (e.g., tumor, polyp) is found in >90% of cases.

Primary Causes

Idiopathic lymphoid hyperplasia (most common in children)

Meckel's diverticulum

Intestinal polyps or lipomas

Henoch-Schönlein purpura (HSP) bowel hematoma

Malignancy (lymphoma or adenocarcinoma, mostly in adults)

• Age 6 to 36 months: The window of greatest susceptibility to lymphoid hyperplasia.
• Recent viral illness: Particularly gastrointestinal or upper respiratory tract infections.
• Cystic Fibrosis: Thick inspissated stool can act as a lead point.

A 'lead point' (whether hypertrophied lymphoid tissue or a pathological lesion) is caught by peristaltic waves and dragged forward into the distal bowel. The intussusceptum (proximal segment) enters the intussuscipiens (distal segment). This mechanical invagination compresses the trapped mesentery. Initially, lymphatic and venous return is obstructed, causing massive mural edema. This leads to mucosal bleeding ('currant jelly' stool). Eventually, arterial inflow is cut off, causing ischemic necrosis, transmural gangrene, and perforation leading to peritonitis.

Characteristic Clinical Presentation

• Colicky Abdominal Pain: Sudden, severe, intermittent pain. The child typically pulls their knees to their chest and cries inconsolably during episodes.
• Vomiting: Initially non-bilious, progressing to bilious vomiting as obstruction worsens.
• Asymptomatic Intervals: Between pain episodes, the child may appear perfectly normal and playful, or progressively lethargic.
• Lethargy: Profound, shock-like lethargy can be the sole presenting symptom in infants.

Physical Examination Signs

• Palpable 'sausage-shaped' mass in the right upper quadrant or epigastrium
• Dance's sign (empty space in the right lower quadrant due to cecum moving superiorly)
• 'Currant jelly' stools (a mixture of sloughed mucosa, blood, and mucus - a late and ominous sign)
• Signs of peritonitis or shock in late stages (rigid abdomen, tachycardia, hypotension)

• Bowel necrosis: Death of the intestinal tissue requiring surgical resection.
• Bowel perforation: Leading to gross fecal contamination of the abdomen.
• Septic Shock: Secondary to peritonitis, potentially fatal.

Diagnostic Criteria & Guidelines

Clinical picture combined with an ultrasound showing the classic 'target' or 'doughnut' sign, or diagnosis during therapeutic air/contrast enema.

Differential Diagnosis

• Gastroenteritis
• Incarcerated Inguinal Hernia
• Volvulus / Malrotation
• Meckel's Diverticulum bleeding

Laboratory Tests & Biomarkers

• Complete Blood Count (CBC): May show leukocytosis if ischemia or infection is present. Anemia if bleeding is severe.
• Basic Metabolic Panel (BMP): May show electrolyte derangements (hypokalemia, alkalosis) secondary to vomiting.
• Lactic Acid: Elevated in cases of bowel ischemia.

Imaging Modalities & Findings

• Abdominal Ultrasound: Test of choice. Shows a 'Target sign' (transverse view) or 'Pseudokidney sign' (longitudinal view) demonstrating layers of bowel within bowel.
• Abdominal X-Ray: Often normal early on. May show a soft tissue mass, lack of gas in the right colon, or free air (pneumoperitoneum) if perforated.

• Early
  Intermittent pain, reducible by enema. Venous congestion only.
• Late/Complicated
  Arterial ischemia, irreducible, presence of peritonitis or perforation requiring surgery.

Second-Line & Adjunctive Therapy

If non-operative reduction fails, or if there is evidence of peritonitis/perforation: Emergency laparotomy for manual reduction (milking the bowel backwards) or bowel resection with primary anastomosis if tissue is non-viable.

Surgical & Procedural Management

Laparotomy with manual reduction. Resection is mandatory if a pathological lead point is found, if the bowel is gangrenous, or if manual reduction is unsuccessful.

Recommended Lifestyle Changes

• Ensure completion of childhood vaccination schedules (modern rotavirus vaccines have a very low risk of intussusception compared to older versions).
• Monitor closely for recurrence, especially within the first 24-48 hours after reduction.

Patient Counseling & Advice

Inform parents that recurrence happens in about 10% of cases, usually within the first few days, and they must return immediately if symptoms reappear.

Follow-Up & Monitoring Schedule

Admit to the hospital for 12-24 hours post-reduction for observation and rehydration. Tolerate clear liquid diet before discharge.

Preventive Strategies

Prompt management of gastrointestinal illnesses.

Excellent if recognized and reduced early (mortality <1%). Delay in diagnosis rapidly increases the risk of bowel resection and mortality.