No Heartbeat - Help

I have a friend who has been struggling with fertility for a couple years. She has gone through her first round of IVF. (I, too, am TTC, but I haven’t been trying long enough for my doctor to entertain any fertility treatments. Please forgive my ignorance of the process. I’m learning.) She got a positive, and went to her f/u appt today where they didn’t find a heartbeat. She’s 5-6 weeks. I have heard stories of women who have an US, and a sac isn’t found at 5-8 weeks, but later - after 12 weeks - a sac can been seen via US. Does “not finding a heartbeat” mean that there wasn’t a heartbeat there, or does it mean the the tech/dr just didn’t find it? She has a D&C scheduled for Wed. I want this for her so badly and am holding out hope that there is still a chance a heartbeat can be found if they check next week. Does anyone have any suggestions or similar experience? Please help.