HCG Trigger Shot/IUI Timing

Hello! I have a question regarding the timing of my IUI and would appreciate any input.

This month I took 50 mg of clomid days 3-7, and went in on Monday, Dec. 24, cycle day 12 for an ultrasound which showed two follicles each at 24mm. So the nurse told me to give myself the trigger shot between 9-10pm and come in on Wed. at 10am for my IUI. Tuesday was Christmas so they had to do it on Wed. The question I have is regarding my temperatures post shot.

I have been charting my cycles for the past 1 1/2 years since trying to conceive and whenever my temperature rises above 98.0 I have ovulated. This was true last month with my IUI as well. However, Monday when I took my temperature it was 97.6 and Tuesday had gone up to 98.3 and Wednesday even higher to 98.4. I am worried I either ovulated before the shot or right after.  The nurse at my RE's office said they do not go by temperatures but did say the shot does not usually increase temperatures that much. They did not do an ultrasound before the IUI to make sure I had not already ovulated. If I did ovulate Monday night would that make the IUI on Wed. at all likely to succeed? I know there is nothing I can do this cycle but I want to be prepared next cycle. Should I insist on an ultrasound before the IUI if my temperature seems suspicous of ovulation or just stop temping and go only on what my nurse tells me to do.  Sorry this is so long but I would really appreciate any advice for how to proceed in the future. Thank you.

[Forum-M.D.-SP]

It is unlikely that you ovulated before the IUI. Usually ovulation occurs 36h after the HCG. I would not rely on temperature elevation to accurately time ovulation. By the time temperature is clearly elevated, you are actually past the stage of peak fertility. There was a study done several years ago in which several infertility specialists were asked to pinpoint the time of ovulation based on temperature charts, compared with accurate timing base on detecting an LH surge, and the study proved how inaccurate temp charting is. Your IUI was timed exactly how I would do so in my practice, regardless of Christmas, etc. Hope things work out for you this month!