<prompt> Most impoant investigation for ectopic pregnancy:Serial f3-hCG levelsTransvaginal USGProgesterone measurementCuldocentesis  <response>: If TVS reveals an intrauterine gestational sac,the diagnosis of ectopic can usually be ruled out .sometimes a psuedosac may be seen in an ectopic due to bleeding produced by separation of a decidual cast.refer pgno:159 sheila 2 nd edition 