Intussusception occurs when part of the intestine invaginates into its own lumen for a variable distance, rather like a telescope folding closed. Intussusception may be ileo-ileal, ileo-colic or ileo-ileo-colic. Very rarely the colonic intussusception can even prolapse through the rectum. However, it most commonly involves terminal ileum 'telescoping' into caecum/colon through the ileocaecal valve. The invagination is caused by peristalsis and it is the most common cause of obstruction in infants (but not in neonates).
Mostly occurs in infants between the ages of 3 - 18 months, and although it can occur at any age it is a lot less common.
It most commonly occurs when the ileum passes through the ileocaecal valve into the caecum and colon. Peristalsis acting on a hypertrophied Peyer's patch and Meckel's diverticulum are recognised causes. There is often no cause found though.
- Colicky, severe to begin with.
- Becomes constant and stopping abruptly, then returning with increasing frequency and intensity.
- Child may appear to be "climbing" person cuddling them, unable to stay still. The opposite of peritonitis.
- May be projectile.
- Possibly bile stained.
REDCURRENT JELLY' STOOL*
- Blood stained mucus.
- May be present in nappy or on PR examination.
- Tends to be a late sign.
- Only happens if bowels are opened.
- *Classic MCQ question!
FEATURES OF SHOCK
- decreased urine output
- Sausage shaped mass sometimes palpable.
- >40% of children.
- Hypotensive (late sign).
Occasionally used, may show distended bowel and free gas if bowel has perforated. Some radiologists may insist on this before air enema, but not essential.
Most popular, shows target appearance of intussusception, otherwise known as the "doughnut" or "pseudo-kidney" sign. Can also be used to visualise reduction.
- Remember SHOCK KILLS!
- Manage in surgical centre
- NB IV fluids - immediately to avoid hypovolaemic shock as fluid pools in the gut. Can need upto 40 ml/kg.
- Insufflation: Also known as 'air enema'; successful in 80% of cases; air is pumped into the bowel to reduce the intussusception, with or without balloon inflation, sedation and antibiotics, depending on the person carrying out the proceedure. A pressure of 120mmHg is sustained for over a minute, with at least three attempts if no forward movement. Progress is screened usually with fluoroscopy, or sometimes ultrasound, looking for reduction but also the complication of perforation. The risk of this is <5% in good centres. This is less likely to work when the history is longer or when the child is older. Some centres will not consider this beyond 18 months because a pathological lead point is likely to be responsible and may need resection.If there has been progress but not resolution, it is acceptable to wait a few hours, or even overnight, and then try again.
- Surgery: Only used when less invasive methods fail, when there are signs of peritonitis, if there are multiple recurrences or if the child is older. It may simply reduce with general anaesthetics and not need ressection, but if there is a pathological lead point, damaged bowel or if it is irreducable, the intussusception will need to be ressected. Some surgeons take lymph node biopsies but this just shows inflammatory changes.
Prognosis is excellent. These is around a 5% rate of recurrence, which is higher in those who have air enema reduction, but lower in those who have surgery. Without prompt treatement this condition can lead to bowel necrosis, perforation of the bowel and even death.