Overview
Intussusception
1. Clinical Overview
Summary
Intussusception is invagination (telescoping) of a proximal segment of bowel (intussusceptum) into an adjacent distal segment (intussuscipiens). It is the most common cause of intestinal obstruction in infants aged 6-36 months. The classic presentation is intermittent colicky pain, vomiting, and "redcurrant jelly" stool, though the complete triad is present in only 20-30% of cases. Diagnosis is confirmed by ultrasound, and non-operative reduction (air or hydrostatic enema) is the first-line treatment. Surgical intervention is required for failed reduction or complications. [1,2]
Key Facts
- Incidence: 1-4 per 1,000 live births; most common GI emergency in infants. [3]
- Peak Age: 6-36 months (mean 5-9 months).
- Sex: Male greater than Female (2:1).
- Cause: Idiopathic in 90%; pathological lead point in 10% (especially greater than 3 years).
- Location: Ileocolic (most common), ileoileocolic; rarely isolated small bowel.
- Classic Triad: Intermittent colicky pain (85%), vomiting (75%), redcurrant jelly stool (50% - late sign).
- Diagnosis: Ultrasound (target/doughnut sign).
- Treatment: Air enema reduction (90% success); surgery if fails.
Clinical Pearls
The "Dance Sign": Empty right iliac fossa on palpation (bowel has invaginated away) with sausage-shaped mass in right upper quadrant or epigastrium.
Redcurrant Jelly is a LATE Sign: By the time bloody mucoid stool appears, vascular compromise has occurred. Most children with intussusception do not have this classic finding at presentation.
Think of Lead Points in Older Children: In children greater than 3 years, always suspect a pathological lead point (Meckel's diverticulum, polyp, lymphoma, Henoch-Schönlein purpura).
Post-Reduction Monitoring: After successful enema reduction, observe for 24 hours. Recurrence occurs in 10% (mostly within 72 hours). Repeat reduction can be attempted.
2. Epidemiology
Incidence and Demographics
- Overall Incidence: 1-4 per 1,000 live births per year.
- Peak Age: 5-9 months (range: 3 months - 6 years).
- Age Distribution: 60% less than 1 year old; 80% less than 2 years old.
- Sex: Male greater than female (approximately 2:1).
- Seasonal Variation: Slight peak post-viral illness (autumn/winter).
Aetiology
Idiopathic (90%)
- Associated with viral gastroenteritis, upper respiratory infection.
- Hypertrophy of Peyer's patches acts as a "lead point".
- Post-rotavirus vaccination: Very small increased risk (1-2 per 100,000 vaccinated infants).
Pathological Lead Point (10%)
- More likely in children greater than 2-3 years.
- Must be excluded in older children.
| Lead Point | Features |
|---|---|
| Meckel's diverticulum | Most common pathological lead point |
| Polyp | Juvenile polyp, Peutz-Jeghers |
| Lymphoma | Especially Burkitt's in older children |
| Duplication cyst | Cystic mass on imaging |
| Henoch-Schönlein purpura | IgA vasculitis; intramural haematoma |
| Cystic fibrosis | Inspissated faeces |
| Post-operative | Following abdominal surgery |
3. Pathophysiology
Step 1: Initiation
- Hypertrophied Peyer's patch or lead point creates a focal protrusion.
- Irregular peristalsis pushes the protrusion distally.
Step 2: Telescoping
- Proximal segment (intussusceptum) invaginates into distal segment (intussuscipiens).
- Mesentery is dragged along with the bowel.
Step 3: Vascular Compromise
- Venous Congestion: Mesenteric veins compressed first.
- Oedema: Wall becomes oedematous and friable.
- Arterial Compromise (if prolonged): Ischaemia develops.
- Mucosal Sloughing: Produces "redcurrant jelly" stool (blood-stained mucus).
Step 4: Progression
INTUSSUSCEPTION
↓
┌────────────────────────────────────────┐
│ TELESCOPING OF BOWEL │
│ (Proximal into distal) │
└────────────────────────────────────────┘
↓
MESENTERIC DRAGGING
↓
┌────────────────────────────────────────┐
│ VENOUS OBSTRUCTION │
│ → Congestion, oedema │
└────────────────────────────────────────┘
↓
┌───────────┴───────────┐
↓ ↓
SPONTANEOUS PROGRESSIVE
REDUCTION COMPROMISE
(Rare) ↓
┌─────────────┴─────────────┐
↓ ↓
ARTERIAL GANGRENE
ISCHAEMIA ↓
↓ PERFORATION
MUCOSAL NECROSIS ↓
(Redcurrant jelly) PERITONITIS
Step 5: Obstruction
- Complete mechanical bowel obstruction.
- Vomiting becomes bilious.
- Distension develops.
4. Clinical Presentation
Classic Triad (Present in 20-30%)
- Intermittent colicky abdominal pain - 85%.
- Vomiting - 75% (initially non-bilious, later bilious).
- Redcurrant jelly stool - 50% (blood-stained mucus; late sign).
Symptoms by Frequency
| Symptom | Frequency | Description |
|---|---|---|
| Colicky pain | 85% | Episodic (every 15-20 min); child draws legs up, inconsolable |
| Vomiting | 75% | Initially non-bilious; becomes bilious with obstruction |
| Lethargy | 60-70% | May be only presenting sign in young infants |
| Pallor | 50% | During pain episode |
| Redcurrant jelly stool | 50% | Blood and mucus; indicates ischaemia (late) |
| Refusal to eat | 40% | Non-specific |
| Diarrhoea | 20% | May precede; viral prodrome |
| Normal stool | 30-40% | Early in presentation |
Pain Characteristics
Atypical Presentations
Physical Signs
| Sign | Frequency | Description |
|---|---|---|
| Sausage-shaped mass | 60-70% | Right upper quadrant or epigastric |
| Dance's sign | 50% | Empty right iliac fossa |
| Distension | 50% | Late; indicates obstruction |
| Dehydration | 30-40% | From vomiting |
| Shocked appearance | 20% | Pallor, tachycardia, delayed cap refill |
| Rectal blood on PR | 40-50% | Frank blood or blood-stained mucus |
| Peritonism | 10% | Late; indicates perforation |
Red Flags - "The Don't Miss" Signs
- Peritonitis (rigid abdomen, guarding) → Perforation; emergency surgery.
- Shock (pallor, tachycardia, hypotension) → Aggressive resuscitation.
- Prolonged symptoms greater than 48 hours → Higher risk of ischaemia/perforation.
- Significant rectal bleeding → Vascular compromise.
- Age greater than 3 years → Suspect pathological lead point.
- Bilious vomiting → Mechanical obstruction.
Paroxysmal
Comes and goes every 10-20 minutes.
Severe
Baby screams, draws knees to chest.
Pain-Free Intervals
Child may appear well between episodes.
Progression
Intervals shorten; pain becomes continuous with complications.
5. Clinical Examination
General Assessment
- Level of alertness (lethargy may be prominent).
- Signs of dehydration (dry mucous membranes, sunken fontanelle, reduced skin turgor).
- Vital signs (tachycardia, hypotension = shock).
- Temperature (fever suggests necrosis/perforation).
Abdominal Examination
Inspection
- Distension (late sign).
- Visible peristalsis (if obstructed).
Palpation
- Sausage-shaped mass: Usually RUQ or epigastric; curved, mobile.
- Dance's sign: Emptiness in right iliac fossa.
- Tenderness: Generalised or localised.
- Guarding/Rigidity: Indicates peritonitis (surgical emergency).
Auscultation
- High-pitched bowel sounds (early obstruction).
- Absent bowel sounds (late; ileus or perforation).
Per Rectal Examination
- May reveal blood-stained mucus ("redcurrant jelly").
- May feel apex of intussusceptum (rare).
- Frankly bloody stool suggests ischaemia.
Examination Between Episodes
- Child may appear completely well.
- Mass may still be palpable.
- High index of suspicion required.
6. Investigations
Abdominal Ultrasound (Investigation of Choice)
Gold Standard for Diagnosis
- Non-invasive, no radiation, readily available.
- Sensitivity greater than 98%; Specificity greater than 98%. [4]
Classic Ultrasound Findings
| Finding | View | Description |
|---|---|---|
| Target sign (Doughnut sign) | Transverse | Concentric rings of bowel wall |
| Pseudokidney sign | Longitudinal | Kidney-shaped soft tissue mass |
| Crescent-in-doughnut | Transverse | Mesentery entrapped |
| Trapped fluid | Transverse | Fluid between layers |
| Doppler | Any | Absent flow = ischaemia |
Plain Abdominal X-Ray
Less Sensitive Than Ultrasound
| Finding | Significance |
|---|---|
| Soft tissue mass | RUQ mass; absence of caecal gas |
| Meniscus sign | Crescent of gas at apex of intussusceptum |
| Obstruction pattern | Dilated small bowel loops |
| Paucity of gas in RLQ | Absence of normal caecum |
| Free air | Perforation (rare; urgent surgical indication) |
Contrast/Air Enema
- Diagnostic AND Therapeutic.
- Air enema (pneumatic reduction) or contrast enema (hydrostatic reduction).
- See characteristic "claw sign" or "coiled spring" on fluoroscopy.
Blood Tests
- FBC: Leucocytosis (especially with necrosis/perforation).
- U&E: Dehydration assessment; electrolyte imbalance.
- CRP: Elevated with complications.
- Lactate: Elevated in ischaemia.
- Blood Gas: Metabolic acidosis with shock.
7. Management
Management Algorithm
SUSPECTED INTUSSUSCEPTION
(Colicky pain, vomiting ± mass)
↓
┌──────────────────────────────────────────┐
│ INITIAL ASSESSMENT │
│ - ABC, IV access, fluid resuscitation │
│ - NBM │
│ - Analgesia │
│ - NG tube if vomiting │
└──────────────────────────────────────────┘
↓
ABDOMINAL ULTRASOUND
↓
┌─────────────┴─────────────┐
↓ ↓
CONFIRMED NOT CONFIRMED
↓ ↓
ASSESS FOR Consider alternative
CONTRAINDICATIONS diagnosis; observe or
TO ENEMA discharge if well
↓
┌────┴────────────────────────┐
↓ ↓
CONTRAINDICATIONS PRESENT NO CONTRAINDICATIONS
(Peritonitis, perforation, ↓
shock, prolonged) AIR/HYDROSTATIC ENEMA
↓ ↓
EMERGENCY ┌────────┴────────┐
SURGERY ↓ ↓
(Laparotomy) SUCCESSFUL UNSUCCESSFUL
↓ ↓
24h OBSERVATION SURGERY
(monitor for (manual reduction
recurrence) ± resection)
Initial Management
- NPO (Nil by mouth).
- IV Access: Fluid resuscitation (bolus 20mL/kg if shocked).
- Nasogastric Tube: If vomiting/distension.
- Analgesia: Morphine or fentanyl.
- Antibiotics: If peritonitis or sepsis suspected (broad-spectrum).
Non-Operative Reduction (First-Line)
Air Enema (Pneumatic Reduction)
- Performed under fluoroscopic or ultrasound guidance.
- Air insufflated into rectum under pressure (max 120mmHg).
- Success Rate: 80-95% in uncomplicated cases. [5]
Hydrostatic Reduction (Contrast Enema)
- Barium or water-soluble contrast under hydrostatic pressure.
- Similar success rates to air enema.
- Air enema now preferred (safer if perforation occurs).
Contraindications to Enema Reduction
- Peritonitis (rigid abdomen, diffuse guarding).
- Free intraperitoneal air (perforation).
- Profound shock not responding to resuscitation.
- Symptoms greater than 48-72 hours (relative).
Signs of Successful Reduction
- Sudden reflux of air/contrast into terminal ileum.
- Resolution of ultrasound findings.
- Passage of flatus/stool.
- Clinical improvement.
Post-Reduction Care
- NPO for 4-6 hours, then clear fluids.
- Observation for 24 hours.
- Watch for recurrence (10%).
Surgical Management
Indications
- Failed enema reduction.
- Perforation or peritonitis.
- Profound shock.
- Recurrent intussusception (especially third recurrence).
- Suspected pathological lead point (consider in greater than 3 years).
- Prolonged symptoms (greater than 48-72 hours).
Surgical Options
- Manual Reduction: Gentle retrograde pressure ("milking" the intussusceptum out).
- Resection: If bowel non-viable, perforation, or lead point found.
- Primary Anastomosis: After resection in most cases.
- Stoma: Rarely required; contamination or unstable patient.
Approach
- Laparoscopic reduction increasingly used.
- Open laparotomy (right transverse or midline incision).
Recurrent Intussusception
- Occurs in 5-15% (most within 72 hours).
- First recurrence: Repeat enema reduction.
- Second recurrence: Consider repeat enema or surgery depending on circumstances.
- Third recurrence: Surgery recommended to exclude lead point.
8. Complications
Complications of Disease
| Complication | Incidence | Features | Management |
|---|---|---|---|
| Bowel ischaemia | 20-30% (if delayed) | Redcurrant jelly, metabolic acidosis | Urgent reduction/surgery |
| Gangrene | 5-10% | Perforation risk, shock | Surgical resection |
| Perforation | 3-5% | Peritonitis, free air | Emergency surgery |
| Sepsis | Variable | With necrosis/perforation | Antibiotics, resuscitation |
| Short bowel | Post-resection | If extensive resection | Nutritional support |
Complications of Treatment
| Complication | Incidence | Prevention/Management |
|---|---|---|
| Recurrence | 5-15% | Monitor 24h; may re-attempt reduction |
| Perforation during enema | less than 1% | Air safer than barium; early surgical backup |
| Incomplete reduction | 5% | Repeat enema or surgery |
| Anastomotic leak | 1-2% (post-resection) | Surgical technique; early detection |
9. Prognosis and Outcomes
Prognosis
- Excellent if diagnosed and treated early.
- Mortality: less than 1% in developed countries with prompt treatment.
- Higher morbidity/mortality with delayed presentation, perforation.
Outcomes by Timing
| Presentation | Reduction Success | Bowel Resection |
|---|---|---|
| Less than 24 hours | 90-95% | 5% |
| 24-48 hours | 75-85% | 10-15% |
| Greater than 48 hours | 50-60% | 30-40% |
Recurrence
- After Enema Reduction: 10% (most within 72 hours).
- After Surgical Reduction: 2-5%.
- With Lead Point Excision: less than 1%.
Long-Term Outcomes
- Most children have no long-term sequelae.
- Normal growth and development.
- Rare: Short bowel syndrome (if extensive resection).
Follow-Up
- Clinical review in 1-2 weeks.
- Parent education on recurrence signs.
- Investigate for lead point if recurrent or atypical (greater than 3 years).
10. Evidence and Guidelines
Key Guidelines
| Guideline | Organisation | Key Recommendations |
|---|---|---|
| BAPS/GAPS Guidelines | UK | Ultrasound diagnosis, air enema first-line |
| AAP Committee | USA | Management algorithm |
| APSA Guidelines | USA | Surgical indications |
Landmark Studies
1. Del-Pozo et al. Ultrasound Accuracy (1999)
- Question: How accurate is ultrasound for diagnosis?
- Result: Sensitivity 98.5%, Specificity 100%.
- Impact: Established ultrasound as investigation of choice.
- PMID: 10487587.
2. Kaiser et al. Air vs Hydrostatic Reduction (2007) [5]
- Question: Is air enema superior to hydrostatic?
- N: Meta-analysis; 6 RCTs.
- Result: Air enema slightly higher success rate (91% vs 87%).
- Impact: Air enema preferred where available.
- PMID: 17591558.
3. Jiang et al. Management Review (2013) [1]
- Question: Optimal management strategy?
- N: Systematic review.
- Result: Confirmed enema reduction as safe and effective first-line.
- Impact: Reinforced non-operative approach.
- PMID: 24114913.
4. Buettcher et al. Vaccine-Related Intussusception (2007)
- Question: Does rotavirus vaccine increase risk?
- Result: Small risk (1-2 per 100,000); benefits far outweigh risk.
- Impact: Continued vaccine recommendation with monitoring.
- PMID: 17326826.
11. Patient and Layperson Explanation
What is Intussusception?
Intussusception is a condition where one part of the bowel (intestine) slides inside another part, like a telescope folding in on itself. This blocks the bowel and can cut off the blood supply.
Who Gets It?
- Most common in babies aged 6 months to 3 years.
- Boys are slightly more affected than girls.
- Often happens after a tummy bug or cold.
What Are the Warning Signs?
Classic Signs
- Severe tummy pain: Comes and goes; baby draws legs up and screams during pain, then relaxes between episodes.
- Vomiting: May become green (bile).
- Pale, floppy, or sleepy: Baby may seem very unwell.
- Blood in stool: May look like "redcurrant jelly" (blood and mucus) - this is a late sign.
Take Your Child to Hospital Urgently if:
- Severe cramping pain with pale spells.
- Blood in nappies.
- Vomiting (especially green).
- Very drowsy or floppy.
- Not improving.
How is it Diagnosed?
- Ultrasound scan: A safe scan of the tummy that shows the telescoped bowel very clearly.
- Sometimes an X-ray is done too.
How is it Treated?
Non-Surgical (Enema)
- Air or liquid is gently pumped into the bottom to push the bowel back into place.
- This works in about 9 out of 10 babies.
- Done by doctors in the X-ray or ultrasound department.
Surgery
- If the enema doesn't work, or if there are signs of serious problems, surgery is needed.
- The surgeon opens the tummy and gently pushes the bowel back into place.
- If part of the bowel is damaged, it may need to be removed and the healthy ends joined together.
What Happens Afterwards?
- Most babies recover fully and go home within a few days.
- There is about a 1 in 10 chance it will happen again (usually within a few days).
- If it happens again, it can often be treated with another enema.
When to Seek Help After Discharge
- Return to hospital if:
- Pain, vomiting, or blood returns.
- Not feeding or very sleepy.
- Any concerns.
12. References
Primary Sources
- Jiang J, et al. Childhood intussusception: a literature review. PLoS One. 2013;8:e68482. PMID: 24114913.
- Mandeville K, et al. Intussusception: clinical presentations and imaging characteristics. Pediatr Emerg Care. 2012;28:842-844. PMID: 22929139.
- Waseem M, Rosenberg HK. Intussusception. Pediatr Emerg Care. 2008;24:793-800. PMID: 19018226.
- Del-Pozo G, et al. Intussusception in children: current concepts in diagnosis and enema reduction. Radiographics. 1999;19:299-319. PMID: 10487587.
- Kaiser AD, et al. Hydrostatic versus pneumatic reduction of intussusception. Cochrane Database Syst Rev. 2007;CD006609. PMID: 17591558.
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