6 week abdominal scan

Hey ladies! Just had my 6 week abdominal scan ..doc said everything is progressing well however he said to come back after a week as they didn't detect a heartbeat yet. He said at 6 weeks u generally require an internal scan for heartbeat detection. Have been asked to come back in my 7th week for scan again. Just wanted to know about ur experiences of early scan and if heartbeat is detected at this early stage in an abdominal scan??