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.

Dentists should have a limit on the amount of private work they can do, a think-tank says.

The New Local Government Network, which specialises in public service reform, said imposing a quota would help improve access to NHS dentistry.

It said such a move was justified as it cost £175,000 to train a dentist.

The call comes as the government is reviewing NHS dentistry after heavy criticism of the new contract.

The deal was introduced in 2006 in England - and subsequently adopted in Wales - in a bid to improve access.

But one million fewer patients are actually using NHS services now, compared with when the arrangement started.

Income for dentists is roughly evenly split between private and public patients, but there are signs that younger dentists are more likely to turn their backs on the health service.

In total, there is believed to be 3,000 dentists working solely on private patients, while another 4,000 are spending less than 25% of their time on NHS patients.

To remedy the situation, the think-tank said dentists could be compelled to spend half of their time on NHS patients in return for their training.

Nigel Keohane, from the think-tank, said the government had to adopt a more "nuanced" approach to commissioning dentistry services.

"Dental patients continue to struggle to find NHS practices with capacity to take them," he claimed.

"This limits choice and creates inconvenience for the customer and insufficient supply to meet demand."

It is not the first time the idea of a quota has been floated.

Kevin Barron, chairman of the House of Commons Health Committee, has also supported the move in the past, saying dentists had a "moral obligation" to treat NHS patients.

The government said it was also against a quota, saying it was looking to build on the new contract instead.