Intussusception is uncommon — somewhere between one and four cases per thousand babies in the UK — but it is one of the conditions paediatric A&E doctors actively keep at the front of their minds when a baby under one year old is having sudden severe colicky pain. The reason it sits there is timing: the bowel can be damaged within a few hours if the obstruction is not relieved, and parents who recognise the pattern and come in early get a much better outcome than those who wait it out.
Healthbooq (healthbooq.com) covers acute and serious childhood health conditions alongside the broader early-years content.
What It Is
Imagine a telescope collapsing into itself. That is what is happening in the bowel: one segment slides inside the next. The most common location is at the junction between the small and large intestine, near the appendix.
Once the bowel has telescoped, two things happen. The gut is mechanically blocked, so nothing can pass through. And the inner segment is now squeezed inside the outer one, which compresses its blood vessels — so the trapped section of bowel begins to lose its blood supply. Left alone, the bowel will eventually infarct (die) and perforate.
The peak age is three to twelve months. Boys are affected slightly more often than girls. The cause is usually unknown in this age group. Sometimes a piece of swollen lymph tissue or thickened bowel wall after a viral illness acts as a "lead point" that the bowel telescopes around — which may be why cases occasionally cluster after a stomach bug.
What It Looks Like
The classic story unfolds in three acts.
Act one: sudden, intense colicky pain. A baby who was completely fine ten minutes ago is suddenly inconsolable. They scream, draw their knees up to their chest, sometimes go pale and sweaty. The episode lasts a couple of minutes — feels much longer to whoever is holding the baby — and then it passes.
Act two: the deceptive gap. Between episodes the baby can look almost normal. They might even take a feed or smile. This is the part that misleads parents and sometimes clinicians. The baby looks well, so it must have been a one-off bit of wind. It was not. The bowel obstruction has not gone anywhere; the gut is just intermittently spasming around it.
Act three: it comes back. Fifteen to twenty minutes later, another episode. Then another. Vomiting often appears around this stage — at first just possetting, but later bile-stained (greenish-yellow), which is a hard sign of bowel obstruction in any baby and always warrants the same evening's A&E.
The famous late sign is "redcurrant jelly stool" — a small amount of blood mixed with mucus in the nappy, named for the way it looks. It does not always appear, and when it does, it tells you the bowel mucosa has already been damaged. Do not wait for it. The aim is to make the diagnosis before the redcurrant jelly stage.
A small but important atypical version: some babies do not show the classic episodic pain at all. Instead they go uncharacteristically floppy, drowsy, and unresponsive between episodes — almost as if they are exhausted. A baby who is unusually limp and pale and not feeding properly should be assessed urgently even if there is no obvious abdominal pain.
What Happens at the Hospital
The diagnostic test is an abdominal ultrasound, which shows a characteristic "target" or "doughnut" sign on the screen — concentric rings of bowel inside bowel. It is fast, painless, and usually conclusive. Plain X-rays may show signs of obstruction but cannot diagnose intussusception on their own.
Treatment, in most cases, is non-surgical. A radiologist or surgeon passes a tube into the rectum and uses gentle, controlled pressure of air (pneumatic enema) or contrast fluid (hydrostatic enema) to push the telescoped bowel back out. The whole thing is done under imaging guidance and usually takes minutes.
When the bowel has not yet been damaged and the diagnosis is made within roughly 24 hours of symptoms starting, this works in around 70 to 80% of cases.
Surgery becomes necessary if:
- The enema does not reduce the intussusception
- There are signs the bowel has perforated or there is peritonitis
- The bowel has been compromised long enough that part of it has died and needs to be removed
Most babies who need surgery still recover well, but the recovery is longer than after an enema reduction.
After successful treatment, around 10% of babies have a recurrence — usually within the first 24 to 72 hours, sometimes later. Parents are sent home knowing exactly what to look for, and any return of the same pattern means straight back to A&E.
When to Get Help
Go to A&E now — not the GP tomorrow, not the out-of-hours service in the morning — if your baby has:
- Episodes of sudden severe pain with screaming and drawing up the knees, separated by gaps where they seem oddly settled
- Especially if those episodes are coming back every 15 to 20 minutes
- Vomiting alongside the pain — particularly any green or yellow vomit
- Any blood or mucus in the nappy
- Sudden unexplained floppiness or unusual drowsiness, even without obvious pain
The single biggest preventable problem with intussusception is delay. The condition is uncommon, but the cost of waiting "to see if it settles" is real. If the pattern fits, take them in.
Key Takeaways
Intussusception is a bowel emergency in which one section of intestine slides into the next like a telescope, blocking the gut and cutting off its blood supply. The classic story in a baby aged three to twelve months is sudden episodes of inconsolable screaming, knees drawn up, going pale, lasting a couple of minutes then passing — and the gaps between are deceptive, the baby can look almost normal. The 'redcurrant jelly' nappy is a late sign and you do not want to wait for it. A&E now, not GP tomorrow.
