Intussusception is one of the conditions paediatric emergency doctors think about first when a baby under one year has sudden severe colicky pain. The pattern is distinctive enough that parents who know to look for it can recognise it and get help quickly, which matters because the bowel can be damaged within hours if the obstruction is not relieved.
It is not common: around 1 to 4 cases per thousand children, mainly in the first year of life. But the consequences of delayed diagnosis are serious enough that it is worth every parent knowing the warning signs.
Healthbooq (healthbooq.com) covers acute and serious childhood health conditions alongside the broader early years content.
What It Is
Intussusception occurs when one segment of bowel slides into the adjacent segment, like a telescope collapsing. The most common site is the junction between the small and large intestine. The invaginated bowel cuts off its own blood supply and that of the surrounding bowel. Without treatment, the bowel will infarct.
It affects around 1 to 4 children per thousand in developed countries. The peak age is three to twelve months, though it can occur in older children. Boys are more affected than girls.
The cause is unknown in most cases. In older children and adults it is often associated with a lead point (a polyp, lymph node, or other structure that the bowel telescopes around), but in infants this is less common. Enlarged lymph nodes following a viral illness can act as a lead point and may explain why cases sometimes cluster after viral infections, including rotavirus.
The Clinical Picture
The classic presentation involves three features in sequence. The first is sudden onset of severe colicky pain. The infant screams intensely, draws the knees up to the chest, and may go pale and sweaty. Then, just as suddenly, the pain passes and the infant seems normal or even briefly cheerful.
These episodes recur every 15 to 20 minutes. Between episodes, the child may be quite well-looking, which can mislead parents into thinking the problem is resolving. It is not: the bowel obstruction is ongoing.
Vomiting develops as the obstruction progresses. Initially it may be posseted milk; later it may become bilious (bile-stained, greenish-yellow), indicating a more complete obstruction.
The classic late sign is redcurrant jelly stool: blood and mucus mixed together to resemble redcurrant jelly. This sign indicates that the bowel mucosa is already being damaged. It is a late sign, and ideally the diagnosis is made and treatment begun before this appears.
Some children present atypically with lethargy alone, without the classic episodic pain. An infant who is unusually floppy and unresponsive should be assessed urgently even without obvious abdominal symptoms.
Diagnosis and Treatment
Diagnosis is by ultrasound, which shows the characteristic target sign of one bowel wall nested inside another. Plain abdominal X-ray may show signs of obstruction but is not diagnostic. If the clinical picture strongly suggests intussusception, the child should be referred to a paediatric surgical centre for assessment, not sent home to be observed.
Treatment is by pneumatic (air) or hydrostatic (contrast) enema. Guided by imaging, a tube is inserted via the rectum and gentle pressure is used to push the telescoped bowel back out. This is successful in around 70 to 80 per cent of cases when there is no bowel damage and the obstruction is not too long-standing.
If enema reduction fails, or if there are signs of bowel perforation or peritonitis, surgery is required. Surgeons reduce the intussusception manually and may need to resect (remove) a section of bowel if it has been damaged.
Recurrence occurs in around 10 per cent of cases after successful enema reduction and parents are warned to watch for the same symptoms. Recurrence is less common after surgical reduction.
When to Seek Help
Go to A&E immediately if a baby or young child has episodes of sudden severe colicky pain (crying, drawing up the knees) separated by periods of being well, particularly if vomiting is developing or there is blood or mucus in the nappy.
Do not wait to see if it settles. Delays in treatment significantly worsen outcomes.
Key Takeaways
Intussusception is a medical emergency in which one part of the bowel telescopes into an adjacent section, causing obstruction. It most commonly affects infants between three and twelve months. The classic presentation is episodes of severe colicky pain causing the infant to draw up the knees and cry intensely, separated by periods when the child appears well, followed by vomiting and later the passage of redcurrant jelly stool (blood and mucus). Diagnosis is by ultrasound. Treatment is by air or contrast enema to push the bowel back out; if this fails or if the bowel has been damaged, surgery is required. Early diagnosis significantly improves outcomes.
