Diagnosis and possible complications

How is Kawasaki Disease diagnosed?

There is currently no specific test for Kawasaki Disease and it can be difficult to make a diagnosis, as many symptoms are common to other childhood infections. The diagnosis is made by recognising the symptoms and signs in a child with persistent fever, with no other likely explanation. A test is however being developed and in future this should help families get a rapid diagnosis.

Not all symptoms have to be present for a diagnosis to be made. Kawasaki Disease symptoms can appear one after the other, so may not be present all at the same time. In very young children (babies under one year old) we know that often, there are very few symptoms.

As well as listening to you about your child becoming unwell, and looking at their symptoms, doctors will probably do some blood tests, which might help them decide whether it is Kawasaki Disease making your child unwell, or another illness.

We know that can be distressing and concerning, but until there is a specific test for Kawasaki Disease, we rely on the expertise of doctors and the need to piece together key bits of information to diagnose Kawasaki Disease.

Are there any possible complications?

UK studies have shown that about 1 in 4 children with Kawasaki Disease will develop some heart damage. Some of these will have damage to the blood vessels that supply the heart muscle itself (coronary arteries), resulting from inflammation (swelling). This heart damage is a worry to all parents. It’s important to know though that this damage ranges from mild to severe. For many children, they can recover, but for a few there may be long term damage to their heart.

Problems with the coronary arteries can be detected on a heart scan (an echocardiogram) which your child will have during their stay in hospital. A common type of change which happens in Kawasaki Disease is a swelling of the blood vessels supplying the heart with blood (coronary arteries). This is called a coronary artery aneurysm.

If an aneurysm is found during a heart scan, it might be helpful to know that most of these changes settle over the following two years. This does depend on the nature of any damage caused to a child’s heart by Kawasaki Disease, and of course, how serious the damage is to start with.

But it is important to say that even for those children who do go on to have a long-term problem, whilst they will have to take medication and be monitored closely by doctors, almost all lead a normal life. The diagram over the page explains a bit more about what a coronary artery aneurysm is.

In the months after having Kawasaki Disease, some children can continue to be tired, be ”out of sorts” or moody, have joint pain or tummy upsets that take some time to settle down. All of these issues are known to resolve within a few months but speak to your doctor if you are at all concerned. Societi Foundation also has a leaflet on long term effects experienced by some children, which is available on our website www.societi.org.uk.

What is a coronary artery aneurysm?

The coronary arteries are the blood vessels that supply oxygen and nutrients to the heart muscle. This image represents the human heart and shows the left and the right coronary arteries at a normal size. These arteries can be affected by Kawasaki Disease in some children.

What is an aneurysm?

An aneurysm is a swelling in the artery. This image represents an aneurysm that could be caused by Kawasaki Disease. Aneurysms vary in size and can be a small, medium or large/giant. Doctors use something called a “z score” to help to describe the size of an aneurysm.

What is dilatation?

Sometimes the inflammation of coronary arteries leads to a slight widening of these blood vessels, although they don’t get inflamed enough to cause an aneurysm. Your doctor might describe this change as “dilatation”.  If this happens, your child may have additional scans until their coronary arteries have returned to their normal size.

What is a z score?

A z score allows doctors to understand the size of an aneurysm, relative to the size of the child. This is helpful because a small baby would usually have small blood vessels, but an older child would be bigger and have bigger blood vessels. So, the z score helps doctors to know if the measurements of the blood vessels are healthy for the size of the child or whether there is an aneurysm.

What about blood clots (thrombosis)?

Blood clots can sometimes occur in Kawasaki Disease where coronary artery aneurysms have developed. Their risk is minimised by using medication such as aspirin or clopidogrel, and with ‘blood-thinners’ such as heparin or warfarin.

Can aneurysms rupture?

This is very rare indeed, but very occasionally an aneurysm can rupture. This usually happens early during the disease process.