Fibroid blocking heartbeat???

Asking for my SIL. She went to her first transvaginal ultrasound at 7 weeks 1 day, doc saw sac and fetal pole measuring 7 weeks 4 days(her cycles are shorter than 28 days), as of Thursday past her hcg was 112,000(2 days before it was 99,000) but doc could not find the heartbeat. Doc said the fibroid could be blocking the heartbeat from being found. Asked her to come back in two weeks. Anyone have something similar happen or have any experience as to if this is possible? I know not having a heartbeat this far along is not good but Is there a chance the heartbeat could still be there? I know nothing about fibroids so was hoping someone had some incite.