Are large intestines needed in order to have an ileostomy reversal? what other requirements would be needed?

It depends on why you had the ileostomy.: The normal anatomy will have food going from the stomach through the small intestine into the large intestine. If you had a blockage, an abscess, a cancer, or some other obstructive phenomena that might not be reversible. If you just had something as a diversion procedure and the rest of the gastrointestinal tract is intact, then you may be able to have everything hooked back up again.