Intussusception is the telescoping of the bowel into itself. It mainly is in the ileocolonic region where the terminal ileum invaginate into the caecum through the caecal valve.
The proximal portion of the bowel that invaginates is known as the intussusceptum while the distal portion that receives the invaginating bowel is known as the intussuscipiens (the recipient).
It is more common in boys and most commonly occurs between 5-7 months old and rarely occurs after 2 years old.
Pathophysiology
For us to understand intussusception, we need to first understand the concept of a lead point. A lead point is a variation of the bowel that is trapped by peristalsis. This may refer to a polyp, tumour, haematoma, Meckel’s diverticulum, haematoma or simply an enlarged lymph node. This lead point is the initiating point for the invagination. Simply put, it is the underlying cause or trigger.
As mentioned earlier, intussusception rarely occurs after 2 years old. In these patients it is almost always due to some pathological cause. In children, it is idiopathic most commonly.
The aetiology behind idiopathic intussusception is hyperplasia of Peyer’s patches. Peyer’s patches are groups of lymphoid follicles in the lamina propria of the small intestine that play a role as the first defence against ingested microbes and antigens. An enlarged Peyer’s patch serves as the point in which the bowel can telescope to initiate intussusception. When the bowel telescopes, it drags the mesentery along with it which can impede venous return and also arterial supply which can lead to oedema, mucosal bleeding, ischaemia, necrosis and perforation of the bowel.
Rotavirus and the rotavirus vaccine have been linked to intussusception and the vaccine is contraindicated in patients who have a history of intussusception.
⚠️ Risk factors
Around 75% of caes are idiopathic. The other causes are due to underlying pathology which is especially true in older patients.
- Meckel’s diverticulum
- Lymphoma
- Polyps
- Cystic fibrosis
- Henoch-Schonlein Pupura
- Surgery (post-operatively)
- Viral gastroenteritis
- Rotavirus vaccine
😷 Presentation
- Paroxysmal severe colicky pain - the pain may result in the child drawing up their legs.
- Inconsolable crying
- Lethargy and decreased activity in between the pain episodes.
- Refusing feeding
- Redcurrant jelly stool - this is essentially blood-stained mucus.
- Sausage-shaped mass (on palpation of the abdomen).
- Signs indicative of intestinal obstruction:
- Abdominal distension
- Vomiting
- Absolute constipation
💡 Often children will have a history of a respiratory viral infection preceding the illness followed by features of intestinal obstruction.
🔍 Investigations
- Abdominal examination
- Distension
- Sausage shaped mass
- Peritonism
- Check for signs of dehydration or shock
- 🥇 Abdominal ultrasound - this is the first-line examination of choice. It classically shows the target sign or doughnut sign. It may also show free abdominal air or gangrene in later stages.
- 🏆 Contrast enema - this is contraindicated in cases of peritonitis or perforation. If the contrast media fails to pass through the obstruction then it confirms the diagnosis. It may also prove therapeutic as the contrast may reverse the invagination.
- Abdominal X-ray - may also confirm the diagnosis but has a low sensitivity.
🧰 Management
Initial management of the child includes fluid resuscitation (if there are signs of shock or dehydration). A nasogastric tube may also help decompress the obstructed bowel. We can then look at non-surgical and surgical means for reduction of the intussusception.
This is done in a child who is stable and has no complications or contraindications.
- 🥇 Air insufflation (air enema)
- 🥈 Barium contrast enema
This is done if:
- Non-surgical reduction has failed
- Contraindications present (such as peritonitis, gangrene, perforation)
- Haemodynamically unstable
Surgical management includes manual reduction of the intussusception. If there is necrosed bowel then resection of the bowel is also required.
It is also important to identify and treat any lead point present.
🚨 Complications
- Intestinal obstruction
- Perforation
- Shock