Heartbeat

I went to the ER for cramping wednesday....I been Cramping throughout the day since july 8th and they were getting pretty bad. I finally broke down and took tylenol and even with that they were still uncomfortable so I decided to go to the ER to make sure everything was okay...after 8 hrs. They told me my HCG levels were 31,000 and they could see/hear a faint heartbeat. The only reason why it was faint was because the baby was still so small....is it really possible to see or hear a heartbeat at 5 wks and 3 days?