Gestational sac is seen on TVS as early as :
An intrauterine gestational sac is visualised with transvaginal sonography by 5 weeks of gestation, and an embryo with cardiac activity by 6 weeks. The embryo should be visible transvaginally once the mean sac diameter has reached 20mm.Cardiac motion is usually visible with transvaginal imaging when the embryo is 5mm. Reference: william's Textbook of obstetrics 24th edition page no 196.
18 days from LMP
21 days from LMP
35 days from LMP
42 days from LMP
General obstetrics