Intussusception

Intussusception is a diagnosis I always worry about missing. I've seen it a few times - thankfully when I've been in a centre with paediatric surgery on site. There doesn't seem to be a big tip about how to diagnose it - except to always think of it as a differential. The few cases I've seen have presented with inconsolable abdominal pain with lots and lots of crying - and that has been the predominant symptom.

Epidemiology
- Happens mostly between 3months to 6 years
- Most common 3-12 months but can happen in elderly and adult patients
- 60% of cases are <1 year, 90% <2 years
- Boys: girls 3:2

Patho-physiology
A part of the bowel is pulled into the distal lumen, and peristalsed forward. The bit that is pulled (the prolapsed part) is called the intussusceptum. The bit of bowel that receives the intussusceptum is called the intussuscipiens. This process is likened to a piece of bowel telescoping in on itself.
Venous return gets compromised causing swelling, and restricted blood flow. Eventually arterial supply to the bowel is interrupted and ischaemia and necrosis happens.

This can occur anywhere:
ileocolic - most common (75-95%)
ileoileocolic - second most common
There is often a "lead point" that causes the intusussception - maybe a hypertrophied Peyer’s Patch. In adults a lesion is more likely. It is a complication of HSP in 2-6% of cases - generally in children >2yrs of age. HSP related intussusception is more likely to be ileocolic.

Clinical Features
- Episodes of abdominal pain - often 15- 20 minutes apart.
- Frequency and severity increase as intestinal oedema increases.
- Vomiting happens in some children. It may be billious.
- There is blood in the stools. In 75% of people with non visible blood stools, occult blood is positve. Jelly stools only happen in 50% of cases.
- Diarrhoea
- The classic triad of colicky abdominal pain, vomiting and redcurrent jelly stools - in 21% of cases only

InvestigationsAbdominal x-rays may demonstrate a soft tissue mass (typically in the right upper quadrant in children) with a bowel obstruction proximal to it. They are negative in 20% of cases! Some suggest if there is no air in the caecum, intusussception is more likely.

Abdominal ultrasound in comparison has 98–100% sensitivity and 88% specificity with a negative predictive value of 100%

Treatment
Air enema
More likely to need operative intervention if:
  Intussusception present >48 hours
  Age <3 months
  Age >5 years (higher likelihood of pathologic lead point)
Even after successful nonoperative reduction the recurrence risk is 10%.

http://pedemmorsels.com/intussusception/
http://www.bestbets.org/bets/bet.php?id=00388
http://bestbets.org/bets/bet.php?id=2372
http://empem.org/2011/09/intussusception/
http://pedemmorsels.com/hsp-and-intussusception/
http://www.pemcincinnati.com/blog/briefs-thoughts-about-abdominal-x-rays-in-intussusception/
http://emj.bmj.com/content/12/3/182.abstract
http://empem.org/2011/10/intussusception-rotavirus-vaccine-risk/
http://westjem.com/images/intussusception-status-post-roux-en-y-gastric-bypass.html
http://radiopaedia.org/articles/intussusception
http://pedemmorsels.com/intussusception/
http://www.pemcincinnati.com/blog/intussusception-1/
http://www.pemcincinnati.com/blog/intussusception-2/
http://www.pemcincinnati.com/blog/intussusception-3/
http://emupdates.com/2009/04/01/intussusception-ssx-dx-rx/
https://www.emrap.org/episode/2008/october/pediatric