<prompt> Yolk sac is seen earliest at what stage of gestational age-5 .5 weeks7.5 weeks10 weeks12.5 weeks  <response>: Ans. is 4a i.e., 5?5 weeks o Using transvaginal sonography, yolk sac always visible at 5?5 weeks gestational age. when mean sac diameter- 5 - 8 mm.o Using transabdominal approach, yolk sac should be evident by 7 weeks gestation, when mean sac diameter is 20 mmo Cardiac activity should be detected at 6 - 6-5 weeks gestation by TVS and 8 weeks by using TAS. 