My SIL had this happen. One twin was ectopic and they didn't know it until her Fallopian tube ruptured and she hemorrhaged at 10 weeks. The other twin, my nephew, survived. Scary ordeal.
They only saw one at 6 weeks and we saw the second at 10 weeks. They were in the same placenta which is, I think, what made it easier to miss so early on.
At my 5 and 6 week ultrasounds, they only saw one sac. We saw two sacs and babies at my 7 week ultrasound.
After 2 years of trying with PCOS, 7 rounds of Clomid/Femara, and 2 early miscarriages, we finally found success. Due on April 24, 2013!
Beta 1 (16 dpo): 477, Beta 2 (19 dpo): 1568, Beta 3 (21 dpo): 3560
Aug 24 - 5w ultrasound - 1 8mm gestational sac
Aug 31 - 6w ultrasound - 1 empty 15 mm gestational sac - possible blighted ovum - Beta 41,716
Sept 7 - 7w ultrasound - 2 sacs, heart beats, and fetal poles - TWINS!!
Baby A measuring 6w4d, Baby B measuring 6w6d
I know someone who it happened to, but it was about 15 years ago. I'm guessing technology has gotten a lot better since then.
I'm not sure what the exact week was, but she was about halfway through her pregnancy. During an ultrasound the tech simply said "hey, you didn't tell me you were having twins!" Her DH literally fell out of his chair.
They were identical, sharing a placenta.
Married07.07.07.Mom to 3:Ruby 11/08and Oliver & Austin12/11
Re: missed twin?
Lost our first little peanut on 1/17/2012 at 9 weeks and 5 days. We miss you little blessing, but we know you were too perfect for this world.
My multiples/parenting/pregnancy/miscarriage blog
I know someone who it happened to, but it was about 15 years ago. I'm guessing technology has gotten a lot better since then.
I'm not sure what the exact week was, but she was about halfway through her pregnancy. During an ultrasound the tech simply said "hey, you didn't tell me you were having twins!" Her DH literally fell out of his chair.
They were identical, sharing a placenta.