Early Pregnancy Concerns: Understanding Empty Sacs & Delayed Period

Question
I am 36 and found out, unexpectedly, that I am pregnant with #3 (Son- 4, daughter- 19 months). I stopped nursing my daughter 4 months ago and my periods are ranging anywhere between 30-45 days.  My LMP was 10/23 (+/- I did not write it down).  I had a +HPT on Dec 3rd.  I went to the Dr and they did an u/s to determine edd and there were 2 empty sacs.  The u/s tech said I was measuring smaller than my LMP calculated edd.  The Dr sat down and the first thing out of her mouth was that, "This is not a viable pregnancy".  Now that it has been a couple of days I have questions.  I am scheduled to go back for another u/s in a week.  At the time of the u/s I could have been only 5 weeks along.  What is the latest that the fetal pole is visible?

Answer
Since your period ranges between 30-45 days (from the first day of your period until the first day of your next period), it is difficult to determine when, exactly, you conceived. You may have ovulated much later than you thought. On sonogram, only an empty gestational sac would be seen if you were only 5 weeks pregnant. After 6 weeks gestation, we usually can see a fetal pole and a fetal heartbeat. I would repeat the sonogram in one week. If there is no further growth or if you do not see a fetal pole in the two sacs, I'm afraid that your doctor is correct. Remember, in a 45 day cycle, ovulation occurs on cycle day #31 and you may have conceived as late as November 22, so you may only be 3-4 weeks post ovlation.