<prompt> Transvaginal USG can detect fetal cardiac activity in:6 weeks7 weeks8 weeks10 weeks  <response>: Ans. is a i.e. 6 weeks Embryonic investigations suggest that cardiac contractions begin in fetus at 36 days gestational age.deg This is evident on : Transvaginal USG At 6 weeks of gestational age corresponding to 13 - 18mm of MSD Transabdominal USG At 8 weeks of gestational age corresponding to 25 mm of MSD. Note : MSD is mean Sac diameter According to Williams Obs 23e p 200 Using real time sunography with a vaginal transducer fetal cardiac activity -?0 hs seen as early as 5th menstrual week 