In the course of my practice, I have had to see many patients who have rather baffling conditions.

It would take me a while to figure out certain conditions but there are some conditions that have symptoms that do not look familiar to me. I would thus refer patients with these unfamiliar conditions to a specialist in another field.

Recently, I saw a baby with unusual patterning on the skin. The baby was otherwise well without any "red flags": He was feeding well, behaving normally and showing no discomfort at all.

As a paediatrician specialising in allergy, the skin condition I am most familiar with is eczema - a condition where there is dry or red itchy skin that lasts several months.

But this was not eczema.

From textbooks, there was a possible condition called Hypomelanosis of Ito - a rare condition that has implications for the child's future health.

It would have been tempting to succumb to the so-called "rule out" mistake - that is, to think of that condition and order tests to rule it out. This is certain to cause the parents to worry. They would also have to spend their time and money on tests to check for something that is unlikely to be there.

As doctors, we have to make a diagnosis, which is the cause of the patient's condition.

As tempting as it may be to go after the first or most serious diagnosis that comes to mind, no doctor knows everything.

On unfamiliar ground, it may be prudent to pause, reflect, find out more, read up more and, perhaps, seek help.

It can be difficult to profess "I am not the best doctor to help you with this".

However, it would benefit all parties in the long run if the doctor is comfortable with that, and even willing to admit that.

SEEK A SECOND OPINION, BY ALL MEANS

In the case of the child with an unfamiliar skin condition but is otherwise totally well, I knew I needed to get help.

I told the parents that I would need to refer the child to a dermatologist who specialises in seeing children. Simply put, I needed a second opinion from an expert who was far more likely than me to get it right.

The dermatologist said it was a harmless skin patterning. It was what I had originally suspected but neither have the expertise to diagnose, nor the confidence to do so, such that I would not be missing something that is potentially dangerous.

I owed it to the parents to get that second opinion for the sake of their child.

It takes time and money to seek out another doctor, and different opinions may confuse.

If you are doing so because you have doubts, yes. This is because, as I have said, there isn't a doctor who knows everything.

Patients can seek a second opinion if they consult a doctor who realises he is not familiar with the problem, and refers them to a specialist.

Or if they are dissatisfied with the outcome of the initial consultation.

Or if they are in situations where the stakes are very high: This is when the initial diagnosis points towards a severe or terminal illness that requires extensive, expensive treatment.

These are all fine. It gets tricky, though, if dissatisfaction is the reason for getting a second opinion.

BUT THE REASON MUST BE CLEAR

Many patients do have a good basis for being dissatisfied. If the doctor failed to pay attention to the patient's concerns or if the patient feels more can be done, it is completely justifiable to seek a second opinion.

However, this is not so if the patient comes in with a personal opinion and then wants to find a doctor who agrees with it.

And this is despite the doctor providing appropriate care and advice, and having done tests that had consistently proven the patient's opinion may be incorrect.

In this case, it may be prudent to think twice before seeking a second or third opinion.

Again, it is not wrong to seek another opinion if the patient disagrees with the doctor - but if the next doctor also disagrees with the patient, the repeated disagreement is unlikely to be a coincidence. I have seen patients who "doctor-hop", hoping that someone will eventually agree with their opinion and prescribe the treatment they want.

When faced with this situation, I usually make an effort to find out more about the patient's condition. This is because when he has formed an opinion, he may sometimes brush aside bits of the problem that he deems insignificant. This can then lead the next doctor to make the wrong diagnosis, with all of its attendant consequences.

The reverse is also true. Doctors do see patients who have sought them out because the previous doctor appeared to brush aside bits of the problem. This then led to the patient's dissatisfaction as he is concerned that the previous doctor may have made a mistake about his condition.

Patients should not be afraid to seek a second opinion and it may even help to ask their doctor about it. But a second opinion should not be sought just to prove that the patient is right.

•Dr Soh Jian Yi is a consultant at the division of paediatric allergy, immunology and rheumatology at the National University Hospital.