Intussusception
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Direct answer
Intussusception is telescoping of one bowel segment into the adjacent lumen, most often ileocolic, and it is the commonest cause of intestinal obstruction in children aged about 6 months to 3 years. The classic picture is intermittent colicky pain with drawn-up legs, vomiting and redcurrant jelly stool. Ultrasound showing a target sign confirms it, and a stable child without peritonitis is usually treated by non-operative reduction.
What you must remember
- Age and type: the commonest age is between about 6 months and 3 years, and ileocolic is the most common type.
- Classic triad: intermittent colicky pain with drawn-up legs, vomiting and redcurrant jelly stool; the stool sign is a late feature.
- Lethargy: pallor and lethargy between colicky episodes suggest bowel compromise and need urgent review.
- Abdominal mass: a sausage-shaped mass, often felt in the right upper quadrant, is not always present.
- Ultrasound: the target sign on transverse section and the pseudokidney appearance on longitudinal section form the diagnostic pattern.
- Air enema: first-line non-operative reduction in a stable child without peritonitis or perforation, performed under radiological or ultrasound guidance.
- Lead points: Peyer patch hyperplasia after viral infection is typical in young children; Meckel diverticulum, polyps and lymphoma are sought in older children and in recurrence.
- Surgery: indicated for failed reduction, peritonitis or perforation, and perforation is an absolute indication.
Managing a suspected intussusception
An 18-month-old boy has episodes of screaming with his legs drawn up, pallor, and bloody mucus stool after a viral illness. The steps below move from resuscitation to the search for a cause, in the order most emergency teams follow.
- Resuscitate. Establish intravenous access, correct dehydration and keep the child nil by mouth.
- Image. Ultrasound confirms the target sign and shows free fluid or other complications.
- Assess stability. Absence of peritonitis, shock and signs of perforation allows a non-operative attempt.
- Reduce. Perform air enema under radiological or ultrasound guidance, with monitored pressure and repeated checks.
- Recheck. Repeat abdominal imaging after reduction, since a minority recur and some need surgery later.
- Operate if needed. Failed reduction, peritonitis or perforation requires surgical reduction and assessment of bowel viability.
- Search for a lead point. Recurrence or an older child warrants evaluation for Meckel diverticulum, polyps or lymphoma.
The pathway is a race against bowel ischaemia, so delay in recognition raises the chance that surgery will be needed. Recording the time of each step helps the team judge when a non-operative attempt has failed.
Where the exam tries to catch you
Intussusception questions usually test timing: which sign is early, which is late, and when the enema is contraindicated.
- Trap: waiting for redcurrant jelly stool before ordering ultrasound. Correct: that stool is a late sign, and colic with vomiting in this age group is enough to image.
- Trap: attempting air enema in a child with peritonitis. Correct: peritonitis and perforation are contraindications, and surgery is required.
- Trap: treating episodic colic with vomiting in a well-looking infant as gastroenteritis. Correct: intermittent colic with vomiting at this age is intussusception until proven otherwise.
- Trap: assuming a recurrent intussusception needs no further work-up. Correct: recurrence or an older child should prompt a search for a lead point such as Meckel diverticulum or lymphoma.
Frequently asked questions
Which segment is most commonly involved in intussusception in children?
Ileocolic intussusception, in which the ileum telescopes through the ileocaecal valve into the colon, is the most common form in children. Ileo-ileal and colo-colic types are less frequent and are seen in different clinical settings.
Which ultrasound finding confirms intussusception?
The target sign, seen as concentric rings on transverse imaging, confirms intussusception in a child with colic and vomiting. The pseudokidney appearance on longitudinal imaging supports the same diagnosis, and reduced wall blood flow on Doppler raises concern for ischaemia.
Why is air enema reduction preferred for intussusception in a stable child?
Air enema reduction is preferred in a stable child without peritonitis or perforation because it is both diagnostic and therapeutic, and it avoids surgery in many cases. It is performed under fluoroscopic or ultrasound guidance with monitored pressure, and the child is observed afterwards for recurrence.
What are the common lead points in older children with intussusception?
In older children, Meckel diverticulum, intestinal polyps and lymphoma are the usual lead points that cause intussusception. Their presence should be sought when intussusception recurs or occurs beyond early childhood, because they may need surgical treatment.