Epidemiology

Global incidence: The reported global incidence in infants ranges from 34 to 74 cases per 100,000 live births per year. 

Age distribution: Intussusception can occur between 3 months and 3 years; however, most cases occur between 4 and 9 months of age, with a peak incidence around 6 months, which coincides with the period of weaning from breastfeeding.  It is rare in neonates and uncommon after the age of 2.

Sex distribution: Boys are affected more frequently than girls, with a ratio of approximately 3:2.

Etiology

Over 80% of intussusceptions in infants are idiopathic, often associated with hypertrophy of Peyer’s patches following viral infections, such as adenovirus or rotavirus and following introduction of supplementary feeds at 6 months. The enlarged payers patches serve as the lead point in idiopathic intussusceptions. 

A lesser percentage results from the presence of pathological lead points (PLPs), which are usually structural anomalies in the intestines and are found in 5–10% of cases, and are more common in older children. Examples include Meckel’s diverticulum, intestinal polyps, duplication cysts, lymphoma, and Henoch–Schönlein purpura.

Pathophysiology

The lead point acts as a focal traction site during peristalsis, causing the proximal bowel to invaginate into the distal segment. Mesenteric vessels become compressed, leading to ischemia and possible gangrene if untreated. The impaired venous return leads to venous congestion, causing rupture of the veins and bleeding into the lumen of the intussuscipiens. The blood mixed with the mucous produced by the goblet cells causes the red currant jelly stool passed by children with intussusception. 

Clinical Presentation

Classic triad (though seen in <40% of patients):

1. Intermittent colicky abdominal pain: This is usually the first symptom children with intussusception present with. This is typically observed in children as episodes of inconsolable crying, with the child drawing their knees to their chest. 
2. Vomiting: This occurs next and is initially non-bilious, with the child vomiting recently ingested breast milk or food. Vomiting becomes bilious as the pathology progresses. 
3. Bloody “red currant jelly” stools: This is a late sign and an indication of bowel ischemia.

Other symptoms include fever and progressive abdominal distention. Examination findings would include lethargy, dehydration, and shock in advanced cases, palpable sausage-shaped abdominal mass (right upper quadrant), and in advanced cases, the intussusception can be palpated in the rectum.

Diagnosis

Diagnosis is primarily based on clinical suspicion. Any child between 3 months and 3 years who presents with intermittent, inconsolable crying, vomiting, and the passage of red currant jelly stools should be considered to have intussusception until proven otherwise. It is advisable that any child with a history of passing bloody stools be referred promptly to a hospital where comprehensive evaluation and surgical management can be provided, rather than being treated as a case of dysentery. Misdiagnosis of intussusception as dysentery or acute diarrhea has led to significant mortality among affected infants.

Ultrasound (US): This is the gold standard for diagnosing intussusception, with a sensitivity and specificity greater than 95%. It is also cheap, fast to perform, and readily available.  The classic findings include:

1. “Target sign” or “donut sign” in transverse view
2. “Pseudokidney sign” in longitudinal view

Abdominal X-ray: This is not specific for intussusception, as findings are mainly those of intestinal obstruction, such as absent gas in the right lower quadrant, dilated small bowel loops, and multiple air-fluid levels

Contrast enema (air/barium): This procedure is both diagnostic and therapeutic, as barium can be used for hydrostatic reduction of the intussusception; however, it requires fluoroscopy facilities. The classic feature is the coiled spring appearance.

Note that in low-resource settings like Nigeria, when an experienced clinician identifies strong clinical features of intussusception, such as the classic triad of intermittent, inconsolable crying, vomiting, and red currant jelly stools, along with a palpable, sausage-shaped abdominal mass, routine radiologic investigations may not be necessary and may even cause unnecessary delays in surgery. In such circumstances, proceeding directly to surgical intervention without imaging is considered appropriate.

Resuscitation 

Resuscitation should be performed simultaneously with clinical evaluation and in a stepwise manner:

1. Establish intravascular access: Insert two appropriately sized intravenous cannulas. While securing the lines, collect blood samples for:

• Full blood count
• Serum electrolytes, urea, and creatinine
• Blood grouping and cross-matching

2. Fluid resuscitation: Administer normal saline at 20 ml/kg rapidly over 30 minutes to 1 hour

3. Monitor urine output: Insert an appropriately sized urinary catheter. If unavailable, a size 6 feeding tube may be used.

• Normal urine output in children is 1–2 ml/kg/hour.
• If urine output is inadequate, repeat the fluid bolus (20 ml/kg) while monitoring for signs of fluid overload, such as peri-orbital edema or bibasal crepitations on auscultation of the chest

4. Gastric decompression: Insert a nasogastric tube (minimum size 12) to decompress the stomach.

• Measure the volume of effluent drained and administer an equivalent volume of normal saline intravenously to replace the fluid loss

5. Oxygen therapy: Administer supplemental oxygen if oxygen saturation is low.

6. Antibiotic therapy: Initiate broad-spectrum antibiotics:

• Ceftriaxone 50–100 mg/kg/day
• Metronidazole 7.5–10 mg/kg every 8 hours

7. Correct electrolyte imbalances as indicated by laboratory results.

8. Blood transfusion: Transfuse packed cells or whole blood if the child is anemic.

9. Monitoring:

• Check vital signs and urine output hourly.
• Maintain accurate fluid input and output charts.

Note: In facilities where definitive surgical intervention is not available, resuscitation should be performed before referring the child to a center capable of providing expert surgical care. If appropriate resources are not available, the child should be referred immediately without delay.

Definitive treatment 

1.Non-operative management

Non-surgical management is considered for children who present early, within hours of the onset of symptoms, are stable, and have no signs of peritonitis, in facilities equipped with the technical expertise and equipment necessary for non-operative reduction of intussusception. The two main approaches are:

• Hydrostatic reduction: Performed using saline or barium enema under ultrasound guidance.
• Pneumatic reduction: Performed using air insufflation under fluoroscopy or ultrasound guidance.

Outcomes: Success rates range from 70% to 95% in high-income countries. Recurrence occurs in approximately 5–10% of cases

2. Operative management

 Indications for laparotomy include

• Failed non-surgical reduction.
• Signs of peritonitis, perforation, or shock.
• Unavailability of radiologic reduction facilities.
• Resection may be required if gangrene is present.

In LMICs, surgery remains the primary treatment option due to limited resources and late presentations with associated bowel gangrene and peritonitis. 

Intussusception: clinical importance and challenges in LMICs

Intussusception remains a critical pediatric emergency and a leading cause of intestinal obstruction in young children. In well-resourced settings, early recognition and prompt non-surgical reduction utilizing hydrostatic or pneumatic techniques are the standard of care, yielding high success rates and low morbidity.

However, in low- and middle-income countries (LMICs), the management of intussusception is often complicated by multiple systemic and clinical challenges.

Diagnosis in LMICs is complicated by:

• Limited access to imaging: Ultrasound, the gold standard for diagnosis, is often unavailable outside tertiary centers. 
• Late presentation: Delays in seeking care due to long distances from health facilities, poor referral systems, and reliance on traditional healers often result in children presenting with advanced disease, including bowel necrosis and perforation.
• Lack of awareness: Non-specific early symptoms such as diarrhea, vomiting, and fever frequently overlap with infectious gastroenteritis, leading to misdiagnosis.
• Misdiagnosis as dysentery or diarrhea: This frequently results in delayed surgical treatment and contributes to increased morbidity and mortality.

These factors contribute to a higher reliance on surgical intervention, delayed treatment, and consequently, worse outcomes.

Conclusion

Timely referral of children presenting with bloody stools or other signs suggestive of intussusception to facilities capable of definitive surgical intervention is crucial. Early access to appropriate care, combined with rapid resuscitation and skilled management, can substantially reduce the complications and mortality associated with intussusception in resource-limited settings.