how early can a fetus be seen on ultrasound
The first part of the pregnancy that can be seen is the gestational sac. The gestational sac can be seen around cycle days 32-35 (4w+3d-5w+0d), about 18-21 days after ovulation/fertilization, though it sometimes can take a couple of days longer to see the gestational sac on transvaginal ultrasound. On an abdominal ultrasound, the sac can be seen several days later.