Not sure what your diagnosis is or symptoms are, but here is my story. I've had 2 colonoscopies and 2 upper endoscopies. I had both procedures at once in December 2011, post-POTS diagnosis. It took 6 months for all the docs to sign off on the procedure because my HR was too high (before we started the meds to get the HR down for the procedure, my resting HR was 110+). Fortunately, I had a GI doc who knew a little bit about POTS and was very cautious of the high HR. Usually in these minor procedures, you have the option of an anesthesiologist (or their nurse) to be in the room monitoring you through the procedure...I would highly recommend this, even though it's an additional expense. Make sure when you go in for pre-op testing you TELL them everything (don't rely on them to read the piece of paper you fill out in the waiting room). In my case, neither one of the pre-op anesthesiologists I saw knew a thing about POTS (not surprised), but at least they recognized an excessive HR as an issue. The first time I went to get the pre-op clearance, they requested test results from various docs and concluded that I needed to see a cardiologist who would need to evaluate me and sign off. On to the cardiologist, who started me on metoprolol, and after a few adjustment (and 6 months later) I was cleared for the procedure by the cardiologist, as long as I took the metoprolol before the procedure. Back to pre-op for clearance, and it was almost halted. They eventually signed off, but stipulated that if my HR was too high at the time of the procedure, they would cancel it (this is not something you want to hear when you have to "prep" (aka, clean out your system) the night before and it is not a pleasant process. Fortunately, I had had both procedures done in the past, so I knew it was no big deal. Wake up, go home, good to go. Knowing that helped me remain calm before the procedure, which ultimately kept my HR low enough for them to proceed. But, I also had to make sure I was laying down for awhile before the procedure (I asked to come in early to do this...it's the only way I can get my HR down and stabalized) and had to stay cool (I was given ice packs). For me, the colonoscopy is more of a nuisance because of the prep. The procedure itself is relatively quick and painless. I don't remember how I felt after the first one (back in 2004), but this last time, I was just a little sore for a few days, kind of like having menstrual cramps. The moral of the story is, make sure you tell the pre-op anesthesiologist about your condition and any symptoms (HR, BP issues, etc.) so they can determine how best to handle the situation and determine if you need to take some of your meds the day of the procedure (or even come off some meds at some point before the procedure). Also tell them of any problems you may have had with anesthesia in the past (I used to have a hard time waking up, but ever since I started mentioning this to them, I usually wake up feeling pretty good). You may want to also get advice from the doc(s) who are treating your condition. Hope this helps, and best wishes! And in case you're interested in the outcome, they found remnants of internal hemorrhoids (which explained my bleeding), as well as gastritis and something else in the upper realm that I can't remember.