Several years ago, one of my DDs had lower abdominal pain on one side which my OH, a doctor, feared might be an ectopic pregnancy - a very dangerous condition if not diagnosed properly. To cut a long story short, 4 doctors dismissed it; and she took herself off to a private hospital for a scan, from whence she was shipped instantly to the local hospital for immediate surgery with a diagnosis of ectopic pregnancy.
A friend's DD has just had precisely the same thing happen to her. The fourth doctor who saw her did at least do a pregnancy test, which was of course positive, but told her that she just had "normal pregnancy pains" - whatever those might be. The proper diagnosis was made at a private scan, again self-initiated, in spite of the fact that she has been in pain for two weeks and had expressed her concern that it might be an ectopic at every consultation.
Worrying - the end result of these two cases could have been tragic if they had not taken it upon themselves to do something about it.