how many weeks can a yolk sac be seen on ultrasound
Concerns Regarding Early Fetal Development Gestational Age Week 5 (Fetal Age: Week 3) Development. Around 5 weeks, the gestational sac is often the first thing that most transvaginal ultrasounds can detect. This is seen before a recognizable embryo can be seen. Within this time period, a yolk sac can be seen inside the gestational sac.