My 4 year old son was in a pool of cold water. he has been shivering for 1 hour. his lips have gone blue and his entire body has turned bluish. he has no chd. what is the diagnosis and prevention/treatment? should i get an echodone?

Unlikely anything: If your son is growing healthy, meeting his milestones for height/weight/learning, then it is likely because kids will often completely ignore physiologic warning signals (like freezing) to continue play--as long as color returned to normal with rewarming (over 20-30 minutes), then this is likely all it is. If color changes at other (non-cold-exposure) times, definitely see pediatrician.

Hypothermia: Anyone can become hypothermic in a pool. Our body temperature is 98.6 deg f, so any water (or air) below that cools the body. It is worse in water, because it is a good conductor of heat. You describe in the expected reaction the body does to increase core body temperature - decrease blood to the limbs (turn blue) and shiver (to make heat) less pool time, inc pool temp. If repeat, see doc.

Acrocyanosis: A 4 year old will not typically present with heart disease after being in a pool. Acrocyanosis is when a patient appears blue in the extremities, often after being in cold environments. If it resolves and the child is otherwise fine, i would bring it up with the pediatrician, but otherwise not necessarily do anything else. If other problems occur, then please discuss with the pediatrician.