The stiff shoulder that turned out to be Parkinson's Disease. The women told their period pains were all in the mind - but who years later discovered they had endometriosis, which rendered them infertile. Serious medical mistakes - with potentially disastrous consequences.

Of all complaints received by the Care Quality Commission in 2008, 36 per cent related to misdiagnosis or delays in diagnoses by GPs.

In one study, which looked at 1,000 claims brought against GPs, two-thirds involved a delayed or wrong diagnosis, including misdiagnosing serious conditions such as heart disease and cancer.

Katherine Murphy, director of the Patients' Association, said there is nothing worse for patients than a late or wrong diagnosis.

'When it goes wrong, the consequences are obvious, but the illness may not have been that difficult to diagnose,' she says.

'As gatekeepers to the rest of the NHS, a GP's duty to be up-to-date is absolute. The pressure on them is increasing: patients live longer and can have more done for them, but the standard consultation time is still only a few minutes.'

So, what might your doctor be missing? Here are seven conditions that are routinely misdiagnosed, and the red flag symptoms to look for.