I had it done during my treatment. Be lucky that you are getting sedated, I had it performed while awake and it is not comfortable at all but you can live through it (I did) if you want to avoid anesthesia. It does last for 10-15 minutes and those were the longest 10-15 minutes in my life hahaha…
Advice on the preparation part. They will give you a protocol to follow before the procedure and most likely it involves cleansing your colon and not eating for a day or so. There are most likely lots of laxatives involved in the cleanse. Don’t miss your probiotics! I skipped antifungals but kept the vitamins. Also, make sure that you take in a lot of liquids to stay hydrated and have your meat day just before and after the procedure. I cooked up a large chicken leg (it contains more fat than chicken breast) with tons of veggies (cabbage, kale, onion, garlic, celery root, celery stalks, carrot – you don’t eat it, potato – you don’t eat it, and anything else that comes to mind) in at least 2 quarts of water and then you strain it. Eat the chicken and any of the allowed veggies day before and then drink this stock on the day you cannot eat (add sea salt in it and that’s it). It will give you nutrients you need so you don’t feel like passing out. I did the same again after the procedure but I ate the chicken and veggies and drunk the stock instead of water to recover faster. I was great those two days, the stock kept me from being hungry and weak.