IUI -- Determining how many follicles released?

How do they determine post IUI via ultrasound how many follicles released?

I have not been able to find any information explaining this on the net.

I had one at 24mm and one at 13.2mm.  I know that the follicle (Clomid 50mg) can grow 1-2 mm between trigger shot and IUI.  

I went in and had ultrasound post IUI to confirm I ovulated.  I did and they said that I for certain released one follicle.  What about the other one that could have possibly been mature enough to release?

Thanks

[BeeHappy76]

My doctor basically told me that they released when they were "gone" on the next u/s. I don't know if there is a more high tech way than that - maybe he was just simplifying the explanation for me.

I also had one at 13 mm before trigger and my doctor said that it would be too small to catch up in time. I think they need to be at least 18 by the time they release. My smaller ones were also "gone" by the next u/s, so I'm not sure if that means they released and were just too small to be fertilized, or what exactly happened to them.

Best of luck to you! When I got pg I only had 1 mature follicle - that is all you need!

[CCP2727]

Thanks very much!  Crossing my fingers!

The thing that confused me was that they made a point to explain to me that at 13.2 it could catch up to 15mm by IUI. They were basically making sure I was aware there was a possiblity - however remote -- of twins.  I guess anything could happen, and probably has...so they still cover all their bases.  It is funny because at the piuiu/s they were like, yay, it was too small anyway?  I have read that with certain shots or certain mg-s of shots that only eggs similar in size will release.  That makes sense...the 24 and 13 were definitely not close in size by any means.

Thanks again, I appreciate your response!