Intussusception

What happens in intussusception

The intestines move food along with waves of muscle contraction called peristalsis. If a segment of bowel becomes thicker at one point, the waves can grab that point and pull it into the bowel just ahead, so the bowel folds into itself.

In children, about 90% of cases are ileocolic: the end of the small intestine (ileum) telescopes into the start of the large intestine (colon). The trapped bowel is squeezed, its veins are compressed and it swells. This causes:

1. Blockage: food and fluid cannot pass, causing vomiting and swelling, as in any bowel obstruction.
2. Reduced blood flow: the bowel lining leaks blood and mucus, producing currant jelly stools.
3. Bowel death and perforation: if untreated for long enough, the bowel can die and burst, causing peritonitis and shock.

Symptoms of intussusception in babies and children

• Sudden episodes of severe abdominal pain: a baby screams inconsolably, goes pale and pulls the knees up to the chest. Episodes last a few minutes and recur every 15 to 20 minutes, becoming more frequent.
• Calm between episodes: the child may seem fine, or increasingly tired.
• Vomiting: at first stomach contents, later green bile.
• Currant jelly stools: a mix of blood and mucus, usually a later sign. Many children do not have it at diagnosis.
• A sausage-shaped lump in the belly that a doctor may feel.
• Lethargy: some babies, especially younger ones, present mainly with floppiness and sleepiness rather than obvious pain.
• Fever and a swollen belly as the illness progresses.

Only about a quarter of children have the classic trio of pain, a lump and bloody stools, so doctors rely on suspicion and an ultrasound.

Causes and risk factors

In children

Most cases have no single clear cause. Swollen lymph tissue (Peyer's patches) in the bowel wall, after a viral infection such as a cold or gastroenteritis, is thought to act as the leading point. This explains why intussusception is more common in spring and autumn.

A lead point (a structure that the bowel pulls along) is found in about 5 to 10% of children, more often in those over 3 or under 3 months:

• Meckel's diverticulum, a small pouch present from birth
• polyps, duplication cysts or lymphoma
• bleeding into the bowel wall from IgA vasculitis (Henoch-Schönlein purpura)
• thick stool in cystic fibrosis

Rotavirus vaccine

Rotavirus vaccines carry a very small increased risk of intussusception, mostly in the week after the first dose, estimated at roughly 1 to 6 extra cases per 100,000 vaccinated infants. Health authorities including the CDC conclude that the protection against severe rotavirus diarrhea far outweighs this risk. Watch for the warning signs after vaccination.

In adults

Intussusception is uncommon in adults, and around 9 in 10 cases have an identifiable cause, often a tumor (benign or cancerous), polyp, scar tissue from surgery, or a feeding tube. Symptoms are usually vaguer: crampy pain that comes and goes for weeks, nausea and bloating. Brief, small-bowel intussusceptions without a lead point are sometimes seen on CT scans and often resolve on their own.

How it is diagnosed

• Examination: the doctor looks for dehydration, a mass in the belly, and blood on a rectal exam.
• Ultrasound: the first-choice test in children. Intussusception appears as a "target" or "doughnut" of bowel layers in cross-section. In experienced hands it is highly accurate and uses no radiation.
• X-ray: may show blockage or free air from a perforation but cannot rule intussusception out.
• CT scan: usually used in adults, where it also shows the lead point.

Treatment

Enema reduction

In a stable child, a radiologist inserts a soft tube into the rectum and gently pushes air or liquid contrast into the colon under X-ray or ultrasound guidance. The pressure pushes the telescoped bowel back into place. This works in about 80 to 90% of children. The risk of perforating the bowel is about 1%, so a surgical team is kept available.

Children are watched for some hours afterward and often go home the same day or the next. Intravenous fluids and pain relief are given before and during treatment.

Surgery

Surgery is needed when:

• the enema does not work
• the child is in shock or has signs of perforation or peritonitis
• a lead point needs removing

The surgeon gently squeezes the bowel back into place. If a segment has died or there is a lead point, that part is removed and the ends rejoined. Surgery is often done by keyhole (laparoscopy).

Adults usually need surgery, because a tumor is often the cause.

Complications

• Recurrence: about 1 in 10 children has another episode, most within the first few days or months. It is usually treated with another enema.
• Bowel death and perforation if diagnosis is delayed
• Dehydration and sepsis

Outlook

With treatment in the first 24 hours, nearly all children recover fully, with no long-term effects. Delays increase the risk of bowel damage, need for surgery and complications. In adults, the outlook depends on the underlying cause.

Frequently asked questions

What are the first signs of intussusception in a baby?

The first sign is usually sudden, intense crying in short bursts, with the baby going pale and drawing the knees up, every 15 to 20 minutes. Vomiting often follows. Between attacks the baby may seem normal or very sleepy. Bloody, jelly-like stools come later, so do not wait for them.

What does currant jelly stool look like?

It is stool mixed with dark red blood and mucus, giving it a glistening, jelly-like look similar to red currant jelly. It shows that the bowel lining is losing blood supply. In a baby or toddler it needs emergency assessment, though many children with intussusception never have it.

Can intussusception fix itself?

Short episodes, especially in the small intestine, sometimes undo themselves, and these are occasionally seen on scans in adults. In children with symptoms you cannot rely on this. Intussusception needs urgent medical treatment because the trapped bowel can lose its blood supply within hours.

Is intussusception in adults serious?

Yes, usually. In adults, intussusception is rare and most cases are caused by a growth in the bowel, which can be a cancer. Treatment is generally surgery to remove the affected segment, and the tissue is examined to find the cause.

Can the rotavirus vaccine cause intussusception?

There is a very small increased risk in the week after the first dose, around a few extra cases per 100,000 babies. Rotavirus itself causes far more hospital stays, so the vaccine is still recommended. Seek urgent care if your baby has crying spells, vomiting or bloody stools after vaccination.

How long does recovery take after intussusception?

After a successful enema, most children eat normally within a day and go home within 24 to 48 hours. After surgery, recovery in hospital takes a few days to a week, depending on whether any bowel was removed. Watch for symptoms returning in the following days.