Hi, did the gynae say how many weeks your sis is in? For my case, I went for scanning at about week 5+.. cant see at all. the gynae had to use the viginal scan thing, go in from below to scan for the sac. but still manage to find it in the end.. but took quite some time to locate the sac. perhaps you can ask her go back to the clinic to scan in another 2 weeks time. its still too early to be detected thru the normal ultra scan machine.