Rheumatic fever - Diagnosing rheumatic fever
NHS Choices Medical Reference
As rheumatic fever can cause so many different symptoms, a type of checklist known as the 'Jones Criteria' is used to help in the diagnosis process.
The Jones Criteria involves checking whether you have certain signs and symptoms strongly associated with rheumatic fevers. These signs and symptoms are collectively known as criteria.
There are two types of criteria:
major criteria, which are signs and symptoms strongly associated with rheumatic fever, and
minor criteria, which are signs and symptoms moderately associated with rheumatic fever.
The criteria are listed below:
Carditis: inflammation of the heart.
Polyarthritis: where several joints become stiff, painful and swollen.
Chorea: jerky involuntary body movements.
Erythema marginatum: red or pink rash on the skin.
Subcutaneous nodules: small lumps under the skin that tend appear on the elbows, knees, ankles and knuckles.
Arthralgia: joint pain, but less severe than arthritis joint pain.
Fever: usually over 39ºC (102ºF).
Elevated ESR or CRP: erythrocyte sedimentation rate (ESR) and C reactive protein (CRP) are both types of blood tests that can detect inflammatory conditions (see blood tests below).
Prolonged PR interval: irregular heart rhythm.
A confident diagnosis of rheumatic fever can be made if you have at least two major criteria or one major and two minor criteria.
While some of the criteria listed above can be assessed by a physical examination and asking you (or your child) about your symptoms, others, such as inflammation of the heart, will require testing to confirm. Tests used in the diagnosis of rheumatic fever are outlined below.
To help confirm a diagnosis of rheumatic fever, you will usually be required to have an electrocardiogram (ECG). During an ECG up to 12 adhesive electrodes are attached to certain areas of the body, such as the arms, legs and chest. A machine will then measure the electrical activity of your heart, so that your doctor can check for any abnormal heart rhythms. Inflammation of the heart is a common complication of rheumatic fever, and so it is important that any abnormal heart rhythms are detected early on so that prompt treatment can be given.
A number of different blood tests may be used to look for indications of rheumatic fever. The first tests the level of C reactive protein in your blood. CRP is produced by the liver. If there is more CRP in the blood than usual then this means there is inflammation in the body.
Another blood test is known as erythrocyte sedimentation rate (ESR). In an ESR test a sample of your red blood cells are placed into a test tube of liquid. They are then timed to see how fast they fall to the bottom of the tube. If they are sinking faster than usual, this could mean that you have an inflammatory condition such as rheumatic fever.