Diagnosis of arthritis should be done as early as possible as the joints bear more and more irreparable damage with time. This is true for all the types of arthritis. Septic arthritis, which is a type of arthritis, also is not an exception to this.

Septic arthritis is a type of arthritis in which infection attacks the joints and gives rise to the symptoms.  When the symptoms of arthritis occur in the patient, he should consult a rheumatologist. Two types of tests are capable of detecting septic arthritis. They are the laboratory tests and the radiological tests.

For the laboratory test would include studying the sample of synovial fluid from the affected joint. Different aspects of synovial fluid are tested. Some of the prominent ones are leukocyte count, presence of gram stain, polarization of synovial fluid, whether some other abnormalities are present in it, etc.

Among these, the tests as the gram stain test and polarization are very fast and therefore they are done first among the laboratory tests. They are accurate most of the times; however, they are not useful when the infection is in the primary stage.

Culture of the synovial fluid also is among the important tests done for diagnosis of arthritis in case of septic arthritis. The synovial fluid from the affected joint is cultured for some time. If the infection is present, it will grow and therefore will be easily detectable. This method is useful in case of the initial stages or the other laboratory tests do not work.

These are the generally laboratory tests. However, septic arthritis can be caused by a number of different types of microorganisms. Therefore, sometimes some different tests, which can detect them, are used.

The radiological images are not useful for detecting the infection itself. However, in the later stages when the tissues present in the joints are affected the changes can be detected by the radiological images. Therefore, these radiological images are used to study the effects on the joints and therefore the damage occurred and the severity of the septic arthritis can be known.

Some of those things in detected by the radiological images are swelling or any abnormality in the soft tissues, occurrence of deposit of some material, effusions abscesses, etc. but as these things occur only during the later stage it can be useful for diagnosis of arthritis only then.