Hope this isn't too dumb a question. We're not doing IUI (yet), but I have been doing Femara with u/s monitoring and trigger and TI.
Long story short(ish), I got a +OPK and have two follies that showed on u/s: 13 mm and 17 mm. The doctor wants me to come in for b/w to confirm the LH surge and probably trigger Saturday. I don't understand why I need a trigger shot if I'm already surging. What good that would do anyway? I need to decide like five minutes ago anyway, so it may be a moot point.
TIA for helping me understand.

15 treatment cycles: four early m/c
Moving forward with domestic infant adoption!
Home study approved 5/13, now just waiting...
Re: Why do you trigger?
just a few down.
The trigger mimicks your LH surge and maturates your follicles. It's generally done for IUI and IVF so that the procedures can be scheduled accordingly.
Yes, antagonists or agonist drugs will prevent you from triggering, but you can still use a trigger for cycles where these meds are not used.
The trigger will force ovulation. Especially helpful when you're going to go through a procedure and the RE wants you to get the timing correct for optimal results and if you have multiple follicles that need that extra push.