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I Am On Clomid: What Cycle Day Should The IUI Be Done?

Dear Doctor,

I am on clomid and doing intra uterine insemination. On Cd 5-9, I ovulated. On Cd 18-20 I had an u/s (ultrasound) and cd 13 follies were 8,13,20,20,21. Uterine lining was 6. Will my lining thicken until I ovulate? Should I have an u/s on cd17 instead of cd13? Basically I want to know if cd13 is optimal because typical ovulation is cd14, or is it just the only day to judge?

Thank you! J. from N. Dakota


Hello J.,

The purpose of the ultrasound is to determine

(1) if you are responding to that dose of Clomid,

(2) how many follicles are present and

(3) when to trigger ovulation.

It is not based on a specific time in the cycle. It needs to be done early enough to detect the follicles before they get too big or ovulate spontaneously.  In your case, your lead follicles were 21, 20 and 20 mms on CD#13 so these sizes were appropriate for ovulation. You should have been triggered on that day with HCG and begun intercourse the next day or had your IUI’s.  There would be no reason to wait any further.  In fact, if you allow the follicles to grow past 24 mms, the eggs will be overmatured and not viable.

In terms of your lining, it is thin because it should be 9 mms.  There is a possibility that it can reach the appropriate thickness but not likely once the trigger is given (or the LH surge).  I would have given extra estrogen vaginally to try to thicken the lining.  I would recommend that you look this page on my website where I describe Clomid cycles in detail “Ovulation Induction Cycle“.

Good Luck,

Dr. Edward J. Ramirez, M.D., FACOG

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