An ultrasound can confirm pregnancy as early as 4 to 5 weeks following the last menstrual period (LMP). At this stage, a gestational sac might be seen in the uterus and followed by yolk sac at 5 – 5.5 weeks. Fetal heartbeat may be visible at 5.5 – 6 weeks through transvaginal scan and 7 weeks from transabdominal scan. However, it might differ from each case.