Progression of intussusception.

The position of the apex in intussusception indirectly reflects the length of the intussusceptum in the majority of cases in which the intussusception begins in the region of the terminal ileum. The relationship of the apex to the duration of symptoms and the ease of enema reduction suggests that progression of intussusception occurs rapidly after the onset of symptoms and is normally complete by the time the patient presents to hospital. Further increase in length of the intussusception is probably limited by progressive edema of the intussusceptum and by the length of small bowel mesentery available to it. The position of the apex per se is not a contraindication to attempted enema reduction, although once the apex has reached the rectosigmoid region successful enema reduction is less likely.