Intussusception is the invagination of one part of the bowel into another, resulting in obstruction.
The most common site is the terminal ileum invaginating into the caecum. Its incidence rise from 2 to 3 months, peaking at 4 to 9 months of age, and then declining at 18 months.
Intussusception occurs more frequently in boys than in girls, with a ratio of approximately 3:1
Nausea and vomiting, which may be bile stained, are early symptoms of intussusception. Children are in extreme pain, will cry inconsolably, and draw their knees to their chest. Pain may be intermittent because the affected bowel segment may stop contacting. Rectal bleeding, producing the characteristic red currant jelly as blood is mixed with mucous, and lethargy are later symptoms. A sausage shaped mass may be felt on palpation of the abdomen.
Fever is not due to intussusception, but may be caused by ischaemia and subsequent necrosis, leading to perforation, sepsis and fever.
Target sign on ultrasound is confirmatory.
Intussusception may be suspected from the history and examination. Dance’s sign is where the right iliac fossa is retracted in intussusception. Imaging is necessary to confirm diagnosis, usually ultrasound. If gas is visible on an abdominal X-ray it may be indicative of perforation.
- Gastroenteritis – which is consistent with pain, vomiting, mucous stool. Diarrhoea is the most prominent symptom in gastroenteritis.
- Rectal prolapse – similar symptoms but with mucosa projecting from the anus.
Intussusception is treated with an enema – barium, water or air – but surgical reduction may be necessary if the bowel is damaged. There is an excellent prognosis if treated early, but delayed treatment can lead to death.
Peristaltic action pulls the proximal part of the bowel into the distal part. In 10% there may be an anatomical lead point drawing the intussusception and in some cases may follow infection, and there is an association of intussusception following vaccination.
Intussusception may cause ischaemia and damage of the bowel mucosa – if not necrosis of the bowel itself. The damage to the mucosa results in sloughing and mucous in the stool.