The acute and the less frequent chronic intussusception occurs at any age, but the idiopathic type is mainly observed between the 3rd and the 12th month of infancy.

1. Intussusception has a significant morbidity if diagnosed too late, and even deaths may occur.
2. With increasing age the number of children with a recognizable cause of intussusception becomes larger.
3. Some of the children with idiopathic intussusception may be treated by hydrostatic reduction. Nevertheless, the attendance of a pediatric radiologist and a pediatric surgeon is necessary during this maneuver.

In case of idiopathic intussusception a combination of hyperperistalsis with a swelling of the intestinal lymphatic structures following a viral infection is discussed. In intussusception with recognizable cause (symptomatic type) the following lesions may be observed: congenital anomalies such as Meckel's diverticulum; intestinal duplications; malignancies (e. g. non-Hodgkin lymphoma) and invaginations following surgery or trauma.

In contrast to the acute intussusception with an almost complete stop, some passage of the abdominal content may be possible in chronic types of intussusception. Except for the postoperative and the chronic types which remain within the small intestine, the usual intussusception proceeds into the colon for a variable distance.
The intussusception may exclude the cecum and the appendix (ileocolic intussusception), or include it (ileocecal intussusception).

Sudden onset with colicly, severe and intermittent abdominal pain, in infants intermittent crying and tucking up of the legs, paleness and vomiting. The passage of raspberry jelly-like stool due to fresh blood mixed up with mucus does not always occur, and is usually an intermediate sign in the course of the disease; in a later development signs of an obstructive ileus appear. At the beginning of the disease a mass in the right middle or upper part of the abdomen is palpable (intussusception tumor) and it can be felt in case of advanced disease on rectal examination, the latter examination may also produce the passage of blood and mucus. The clinical presentation in postoperative or chronic intussusception is less obvious.

Depending on the time of recognition of the disease the presenting signs and symptoms differ. Spontaneous reductions in the early stage or cure in the late stage by repulsion of the necrotic leading point are anecdotally described. This should not be considered for a wait and see policy or for unusual treatments.

The differential diagnosis includes all causes of surgical abdominal emergencies and of lower gastrointestinal bleeding in childhood.

Ultrasound by a pediatric radiologist. In case of suspected obstructive ileus abdominal radiographs in supine and upright position.
In suspected postoperative or chronic type of intussusception gastrointestinal study with contrast, or CT/MRI with contrast.

In early diagnosed idiopathic intussusception hydrostatic reduction with contrast or air. Surgical treatment in advanced cases or in suspected symptomatic intussusception. If manual reduction is not possible and/or in case of irreversible damage to the intestine resection of the involved part of small intestine.

Recurrences following operative reduction a few percent; following hydrostatic reduction recurrence rate a little more frequent, therefore in the latter treatment close follow-up during 24 hours.
Postoperative obstruction due to adhesions is possible.