Perhaps the most important feature is the variability of the presentation - thus a high index of suspicion is required. Features include the following:
- history of paroxysms of abdominal colic, with screaming and pallor - the child is anxious on examination
- during each bout the infant becomes pale and draws up the legs. Spasms occur at intervals of about ten to 15 minutes, lasting two to three minutes, increasing in frequency.
- vomiting is an early symptom
- passage of blood and/or slime per rectum - this can be quite a late feature
- sausage-shaped mass is palpable in most cases, often in the right upper quadrant, not in the right iliac fossa. A mass is not always palpable in an ileo-ileal intussception, or if it is under the costal margin.
- rectal examination often reveals a mixture of bright red blood and slime descibed as red current jelly on the examining gloved finger. This is a late feature. Rarely the tip of the intussusception can be felt.
If neglected, in less than 24 hours the child may be intensely toxic, have a distended abdomen, and exhibit faeculent vomiting.
Chronic intussusception is rare and presents with much milder features. It may cause failure to thrive.