IUI/trigger shot question

Hello, I did my trigger shot on Saturday 1/28 and then IUI the next day on 1/29. I was wondering for those that have had a successful IUI, when did the HCG from the trigger shot leave your system or what were your tests looking like? Did the test line fade completely then get positive again when you were actually pregnant? Or did a line remain and just got darker when you were actually pregnant? Thank you!