Hello. Thank you for contacting HCM. I have gone through your question and I understand your concern. Blighted Ovum is basically a pregnancy in which the gestational sac forms without any embryo present in it. It usually passes out with cramping and mild to moderate bleeding in the early weeks of pregnancy with the symptoms of pregnancy also subsiding. As it is very small in size due to early gestational age it is quite possible that is not picked up by naked eye. I would recommend you consult your local obstetrician for detailed clinical evaluation, a repeat pelvic ultrasound and further management accordingly. I hope this answers your question. Please feel free to contact HCM again if you have any concerns. Wishing you good health.