Would you please describe for me some examples of this phenomenon.

I can't bypass this one, cause right up my alley, so to speak. You have spelled this medical condition incorrectly. It is intussusception whereby the intestines invert on themselves. It isn't a phenomenon and is not internal growth. It can be quite painful and not all that rare.

If this is in fact what you meant.

Tick

Do you mean Intussusception? This is a condition, as tickle points out, where part of the intestine prolapses itself. An example would be when one part of the intestine slides into the next, sort of like a collapsible telescope.