I'm new to the board here (just made first post yesterday under "new to board; have question" by spml). I have also had many tests and just wanted you to know that this one is easy! I had the colon transit study about 2 weeks ago now. I think its the same as the one you are talking about, although I haven't heard the term "sitz" before.... only called them "markers" for me. The capsule had 21 markers in it. After swallowing it, on the 3rd and 4th day, xrays were taken to see where they were. On a normal person, they would be gone by then. I had all 21 of them there on the 3rd day, and 6 still present on the 4th day. Anyway, don't worry about this test. The only thing for me is that I was very uncomfortable that week. (no laxatives allowed, obviously!!) Good Luck!