Earliest sign of pregnancy on TVS is?

Ans. is 'a' i.e., Gestational sac "The first definitive Sonographic finding to suggest early pregnancy is visualization of gestational sac" - Callen 4th/e p. 114* The gestational sac can be visualized as early 4Vi weeks of gestation and the yolk sac at about five weeks.* The gestational sac can be visualized as early as 4Vi weeks by transvaginal USG and 5 weeks by transabdominal USG.* Fetal heart rate can be detected by TVS at 5-6 weeks.