Overview
Intussusception
1. Clinical Overview
Summary
Intussusception is a paediatric surgical emergency where one segment of bowel telescopes (invaginates) into an adjacent segment, causing obstruction and vascular compromise. It is the most common cause of intestinal obstruction in children aged 3 months to 3 years. The classic location is Ileo-Colic (Terminal ileum invaginates into the caecum). In most paediatric cases, the cause is idiopathic, often triggered by lymphoid hyperplasia (e.g., following viral gastroenteritis or recent vaccination). The classical triad is Colicky Abdominal Pain, Vomiting, and Redcurrant Jelly Stool (Blood + Mucus) – though this full triad is present in only ~50% of cases. Diagnosis is by Ultrasound showing the pathognomonic "Target Sign" / "Doughnut Sign". First-line treatment is Non-Operative Air (Pneumatic) Enema Reduction under fluoroscopy or US guidance (>80% success rate). Surgery is required if reduction fails or if there is perforation/peritonitis. A Lead Point (Meckel's diverticulum, Polyp, Lymphoma) should be suspected in children less than 3 months or >5 years. [1,2,3]
Clinical Pearls
"Target Sign / Doughnut Sign": On Ultrasound, the intussusception appears as concentric rings (Inner and outer bowel walls) = Pathognomonic.
"Episodic Pale Child Drawing Legs Up": Classic presentation. Child cries and draws knees to chest during colic, then becomes quiet/pale between episodes.
"Redcurrant Jelly Stool is LATE": Indicates ischaemic bowel. Do NOT wait for this sign – Ultrasound any child with suspicious symptoms early.
"Air Enema First": Non-operative reduction is first-line. >80% success. Avoids laparotomy.
2. Epidemiology
Demographics
| Factor | Notes |
|---|---|
| Age | 3 months to 3 years (Peak: 5-9 months). Rare less than 3 months or >5 years (Consider lead point). |
| Sex | Male > Female (3:2). |
| Incidence | ~1-4 per 1000 live births. Most common cause of bowel obstruction in infants. |
Risk Factors
| Risk Factor | Notes |
|---|---|
| Viral Illness | Preceding URTI or Gastroenteritis → Lymphoid hyperplasia (Peyer's patch hypertrophy) → Lead point. |
| Rotavirus Vaccine (Historical) | Original Rotashield vaccine was withdrawn due to intussusception risk. Current vaccines (Rotarix, RotaTeq) have minimal/no increased risk. |
| Lead Points (Pathological) | Meckel's Diverticulum, Polyps, Lymphoma, Henoch-Schönlein Purpura (GI involvement), Cystic Fibrosis (Inspissated meconium). More common in older children (>5 years). |
3. Pathophysiology
Mechanism of Intussusception
- Intussusceptum: The proximal segment of bowel that invaginates INTO the distal segment.
- Intussuscipiens: The distal segment that receives the intussusceptum.
- Common Type: Ileo-Colic – Terminal ileum (Intussusceptum) invaginates into Caecum (Intussuscipiens).
- Mesentery Dragged In: The mesentery of the intussusceptum is dragged into the intussuscipiens → Venous congestion first, then arterial compromise.
- Ischaemia and Necrosis: If untreated → Bowel wall necrosis → Perforation → Peritonitis.
Lead Point
| Definition | In most paediatric cases, no anatomical lead point is found (Idiopathic – ~90%). |
|---|---|
| Pathological Lead Points | Meckel's Diverticulum, Polyp, Duplication cyst, Lymphoma (Burkitt's), HSP, Peutz-Jeghers polyp. |
| When to Suspect | Age less than 3 months or >5 years. Recurrent intussusception. Failure of non-operative reduction. |
4. Differential Diagnosis
| Condition | Key Features |
|---|---|
| Intussusception | Episodic colic, Drawing legs up, Sausage-shaped mass, Target sign on USS. |
| Gastroenteritis | Diarrhoea, Vomiting, Fever, Sick contacts. Often viral. |
| Constipation | Hard stools, Distended abdomen, May have palpable faeces. |
| Malrotation with Volvulus | Neonate, Bilious vomiting, Shock. EMERGENCY. |
| Incarcerated Inguinal Hernia | Groin swelling, Tender, Irreducible lump. Vomiting. |
| Appendicitis | Older children, Right iliac fossa pain, Fever, Guarding. |
| Meckel's Diverticulitis | Similar to appendicitis. May present with painless rectal bleeding. |
| HSP (Henoch-Schönlein Purpura) | Purpuric rash on buttocks/legs, Arthralgia, Abdominal pain (May cause intussusception). |
5. Clinical Presentation
Classic Triad
| Feature | Notes |
|---|---|
| Paroxysmal Colicky Pain | Sudden episodes of severe pain. Child screams, Draws knees up. Then goes quiet/pale between episodes. |
| Vomiting | Initially non-bilious. Bilious if progresses to complete obstruction. |
| Redcurrant Jelly Stool | Mixture of blood and mucus. LATE sign (Indicates ischaemia). Only ~50% have this on presentation. |
Other Features
| Feature | Notes |
|---|---|
| Pallor/Lethargy | Between episodes. Child looks unwell. |
| Refusal of Feeds | Anorexia. |
| Empty Right Iliac Fossa (Dance Sign) | Caecum has moved up with the intussusception. |
| Sausage-Shaped Mass | Palpable in Right Upper Quadrant/Epigastrium. The intussusceptum mass. |
| Shock | Late sign. Indicates severe ischaemia or perforation. |
"Well Between Episodes"
Characteristically, the child appears well and pain-free between colic episodes early in the disease.
Common presentation.
As disease progresses, child becomes increasingly lethargic and pale even between episodes.
Common presentation.
6. Investigations
Imaging
| Modality | Findings |
|---|---|
| Ultrasound Abdomen | Gold Standard. "Target Sign" / "Doughnut Sign" (Cross-section). "Pseudo-Kidney Sign" (Longitudinal). Shows trapped mesentery and lymph nodes. Sensitivity >95%. |
| Abdominal X-Ray | May be normal early. Signs: Small bowel obstruction (Dilated loops, Fluid levels), Soft tissue mass in RUQ, Absent caecal gas. |
| Contrast Enema (Air or Barium) | Diagnostic AND Therapeutic. "Crescent Sign" / "Coiled Spring Sign" (Contrast outlining intussusceptum). Now primarily used for reduction. |
Ultrasound Signs
| Sign | Description |
|---|---|
| Target Sign / Doughnut Sign | Concentric rings of inner and outer bowel walls on transverse view. |
| Pseudo-Kidney Sign | Layers of bowel wall seen on longitudinal view. |
| Trapped Mesentery | Echogenic fat and lymph nodes within the intussusception. |
Blood Tests (If Unwell)
| Test | Rationale |
|---|---|
| FBC, U&Es | Dehydration, Electrolyte disturbance. |
| VBG | Metabolic acidosis (Ischaemia). |
| Group and Save | In case of surgery. |
7. Management
Management Algorithm
SUSPECTED INTUSSUSCEPTION
(Episodic colic, Vomiting, Lethargy, +/- Bloody stool)
↓
RESUSCITATION
- IV Access
- Fluid bolus if shocked (20ml/kg NS)
- NBM
- NG Tube if bilious vomiting/distension
- Analgesia
↓
IMAGING: ULTRASOUND ABDOMEN
- Look for Target Sign / Doughnut Sign
↓
DIAGNOSIS CONFIRMED?
┌────────────────┴────────────────┐
YES NO (But still suspected)
↓ ↓
Proceed to Reduction Consider Contrast Enema
(Diagnostic + Therapeutic)
↓
CONTRAINDICATIONS TO ENEMA REDUCTION?
- Perforation / Peritonitis
- Haemodynamic instability / Shock
- Prolonged symptoms (Relative: >48 hours)
┌────────────────┴────────────────┐
NO Contraindications CONTRAINDICATIONS PRESENT
↓ ↓
**NON-OPERATIVE REDUCTION** **SURGICAL REDUCTION**
↓ ↓
Non-Operative Reduction (Air Enema)
| Method | Notes |
|---|---|
| Pneumatic (Air) Enema | Preferred method. Performed under fluoroscopy. Air insufflated rectally. Reduces intussusception by hydrostatic pressure. |
| Hydrostatic (Barium/Saline) Enema | Alternative. Saline can be US-guided. Barium under fluoroscopy. |
| Success Rate | >80% for uncomplicated intussusception. |
| Criteria for Success | Reflux of air/contrast into terminal ileum. Resolution of mass on USS. Clinical improvement. |
| Post-Reduction | Observe 12-24 hours. Clear fluids → Diet advance. Watch for recurrence (~5-10%). |
Surgical Management
| Indication | Notes |
|---|---|
| Failed Enema Reduction | Proceed to laparotomy/laparoscopy. |
| Perforation / Peritonitis | CONTRAINDICATION to enema. Straight to surgery. |
| Shock / Haemodynamic Instability | Stabilise then surgery. |
| Lead Point Suspected (Older child, Recurrence) | May need surgical exploration to excise lead point. |
| Surgical Options | Manual reduction (Squeeze from distal to proximal – NOT pulling). Resection if gangrenous bowel or lead point. |
8. Complications
| Complication | Notes |
|---|---|
| Recurrence | ~5-10% after enema reduction. Usually within 72 hours. May have second enema attempt. |
| Bowel Necrosis / Perforation | If delayed treatment. Requires resection. |
| Peritonitis / Sepsis | From perforation. High morbidity/mortality. |
| Short Bowel Syndrome | If significant resection required. Rare. |
| Enema Complications | Perforation during reduction (~0.5-1%). |
9. Prognosis and Outcomes
| Factor | Notes |
|---|---|
| Prompt Treatment | Excellent prognosis. Mortality less than 1% with timely diagnosis and treatment. |
| Delayed Treatment | Risk of bowel necrosis, Resection, Significant morbidity. |
| Recurrence | ~5-10%. Usually responds to repeat enema. |
| Lead Points | Requires surgical excision. Prognosis depends on underlying pathology (Lymphoma vs Meckel's). |
10. Evidence and Guidelines
Key Guidelines
| Guideline | Organisation | Key Recommendations |
|---|---|---|
| Intussusception | APSA / BAPS | USS for diagnosis. Air enema first-line reduction. Surgery for failed reduction or perforation. |
| Acute Abdominal Pain in Children | NICE | USS for suspected intussusception. |
Evidence Points
- Air vs Hydrostatic Enema: Air enema has slightly higher success rate and lower perforation risk.
- US-Guided Saline Reduction: Alternative avoiding radiation. Increasingly used.
11. Patient and Layperson Explanation
What is Intussusception?
Part of the bowel has slid inside another section (Like a telescope). This can block the bowel and cut off the blood supply if not treated quickly.
What are the symptoms?
- Episodes of severe tummy pain – The child screams, Brings knees to chest.
- Between episodes, the child may seem fine but tired/pale.
- Vomiting.
- Blood in the nappy (Looks like redcurrant jam) – This is a later sign.
How is it treated?
- Air Enema: Usually the first treatment. Air is gently blown into the bowel via the bottom. This often pushes the bowel back into place without needing an operation.
- Surgery: If the air enema doesn't work, or if the bowel is damaged, an operation is needed.
Is it serious?
Yes. Without treatment, the trapped bowel can lose its blood supply and die. But with quick treatment, most children recover fully.
Will it happen again?
There is about a 5-10% chance it can come back, usually within the first few days. If it happens again, we can try another air enema.
12. References
Primary Sources
- Stringer DA, et al. Intussusception in children. BMJ. 1992;305(6865):1383-1387. PMID: 1486316.
- Gray MP, et al. Ultrasound diagnosis of intussusception. Am J Emerg Med. 2016;34(1):14-18. PMID: 26560746.
- Beasley SW, et al. Intussusception: Current management and outcomes. Pediatr Surg Int. 2018;34(3):209-215. PMID: 29260295.
13. Examination Focus
Common Exam Questions
- Classic Presentation: "Describe the classic presentation of intussusception."
- Answer: Episodic colicky pain (Drawing knees up), Vomiting, Redcurrant Jelly Stool, Pallor between episodes.
- Ultrasound Sign: "What is the pathognomonic ultrasound finding?"
- Answer: Target Sign / Doughnut Sign (Concentric rings).
- First-Line Treatment: "What is the first-line treatment for uncomplicated intussusception?"
- Answer: Air (Pneumatic) Enema Reduction.
- Lead Point Age: "In which age groups should you suspect a pathological lead point?"
- Answer: less than 3 months or >5 years.
Viva Points
- Ileo-Colic: Most common type. Terminal ileum into caecum.
- Dance Sign: Empty Right Iliac Fossa (Caecum is no longer there).
- Contraindications to Enema: Perforation, Peritonitis, Shock.
- HSP and Intussusception: HSP can cause ileo-ileal intussusception (Due to bowel wall oedema).
Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists.