Contents
Introduction
- Usually a piece of proximal bowel passes inside a more distal piece
- Most commonly, the distal ileum passing through the ielocaecal valve into the colon
- Intussusception requires urgent treatment – most cases do not resolve spontaneously and it can lead to bowel necrosis, peritonitis, sepsis and death if left untreated
It classically presents with intermittent abdominal pain – with periods of acute severe pain and an inconsolable child, interspersed with periods where the child appears completely well.
The classical sign is “redcurrant jelly” stool caused by bleeding of the affected part of bowel.
Imaging may be with x-ray, USS or barium enema – with USS becoming the more preferred first option.
Treatment of choice is “insufflation” whereby gas is blown up the anus to inflate and stretch out the bowel. This is usually done with USS monitoring to confirm resolution. This is successful in 75% of cases. The remainder require surgery
Epidemiology and aetiology
- Usually occurs between 3 months and 3 years
- 65% of cases occur <1 year
- Usually idiopathic
- The most common cause of intestinal obstruction after the neonatal period
Risk factors
There is a very long list of factors that are though to precipitate intussusception although in many cases no obvious cause can be found. Most causes are thought to be related to some sort of mass around which the intussusception can start (the “lead site”). For example, in inflammatory causes (e.g. recent gastroenteritis) there is thought to be a lump of inflamed lymphoid tissue on the mucosa called a Peyer’s patch. Or, after blunt trauma there may be a haematoma, or in appendicitis there is an inflamed appendix.
Some causes that are thought to be more common include:
- Recent episode of gastroenteritis
- Recent rotavirus immunisation
- This is usually an oral vaccine given twice to babies under 6 months of age
- Risk of intussusception between 1 and 6 per 100 000
- Recent surgery
- CF
- Blunt trauma
- Appendicitis
- Henoch Schonlein Purpura (HSP)
- Some sort of intestinal mass, e.g.:
- Polyp
- Lymphoma
- Meckel’s diverticulum – a congenital diverticulum present in the distal ileus in 2% of children. Only 2% of those cases are symptomatic, and this is not always intussusception (e.g. could be rectal bleeding, or obstruction instead).
- Foreign body or “fur ball” (trichobezoar)
Pathophysiology
- The most common location is where the terminal ileum “telescopes” inside the colon
- Can sometimes be so large that it traverses the entire colon and there is a rectal prolapse of the ileum
- Intussusception causes venous obstruction of the bowel – which leads to oedema and mucosal bleeding which causes the classical “redcurrant jelly” stool sign
- This typically occurs about 24 hours after the onset of symptoms
- In the vast majority of cases it does not spontaneously resolve – although it is possible
Presentation
- Abdo pain – colicky periodic severe pain. During the periods of pain, the child is often pale, and may curl up into a ball.
- Examination – a sausage shaped mass is often palpable
- Redcurrant jelly stools – very characteristic, blood-stained mucus in the stool. Usually occurs late in the presentation, and more likely to be passed after a PR exam.
- Abdominal distension
- Shock
- Peritonitis – may occur if there is perforation. Signs include: tenderness, guarding and rigidity
Diagnosis
- Abdominal X-ray – may show distended small bowel ± absence of gas in large bowel – but these are late signs. Rarely, the actual intussusception itself may be visible
- Ultrasound scan (USS) – diagnostic in >90% of cases. Colour flow doppler performed with the USS may also be able to identify areas of ischaemia – evidence of which should prompt urgent surgical intervention due to risk of impending perforation
- Often performed with insufflation as treatment
- Barium enema – previously the gold standard – it is also successful at reducing the the intussusception in up to 70% of cases. Should be avoided if there are signs of systemic illness
Treatment
- The first attempted treatment if peritonitis is not present
- Air is pumped into the anus, in an attempt to stretch the walls of the bowel and reduce the intussusception
- Often conducted under USS guidance to view if the technique is being successful
- This is successful in 75% of patients
- Before insufflation – make sure the surgical team are aware of the patient and on standby for surgery should there be any complication or the procedure is ineffective
- Prophylactic antibiotics to cover gut flora should be given before the procedure
- If intussusception recurs then repeat insufflation procedures are appropriate and can be performed
- Recurrence occurs in 4-10% of cases, usually within 24 hours
The medium used for “insufflation” appears to be not important. Previously barium enema was used, but air or saline are just as effective. The pressure is what is important. 60mmHg will reduce most cases and 100mmHg is considered a definitive reduction. Pressures of 120mmHg or higher are associated with increased perforation risk.
Surgery
- The remaining 25% will require surgery, wither as insufflation is not effective, or peritonitis is present
- If peritonitis is present, patients will also require antibiotic therapy (a broad spec, usually gentamicin, ampicillin or clindamycin)
- Recurrence is 5-10%, slightly higher in non-operative treatments
