Significant, site-specific swelling can make elbow bursitis easy to identify. Nonetheless, a doctor must rule out other possible elbow problems, such as arthritis, tendinitis, a fracture or tumor, before making a diagnosis of elbow bursitis. To do this, a doctor will use some or all of the following diagnostic approaches:
Patient interview. A doctor will ask a patient about medical history and to describe the onset of his or her symptoms, the pattern of pain and swelling, and how symptoms affect lifestyle.
Physical exam. A doctor will examine the patient’s joint, noting swelling, tenderness and pain points, and range of motion. As inflammation of the elbow bursa is clearly visible and palpable, the physical exam is an important part of the diagnosis.
Aspiration and lab tests. A doctor may perform an aspiration, removing fluid from the bursa with a needle and syringe. In addition to relieving pressure and making the patient more comfortable, aspiration provides a fluid sample that can be tested for infection.
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Common tests for infection include:
- Gram stain. A lab test called a Gram stain is used to determine if specific bacteria are present. Not all bacteria will be found with a gram stain, so even if the test comes back negative, septic bursitis cannot be completely ruled out.
- White blood cell count. An elevated number of white blood cells in the bursa’s synovial fluid indicates an infection.
- Glucose levels test. Glucose levels that are significantly lower than normal may indicate infection.
Occasionally lab tests to detect infection are negative even when an infection is present. Therefore, a doctor who strongly suspects septic bursitis may prescribe antibiotics without definitive positive lab tests.
Testing skin temperature. Skin temperature at the patient’s affected elbow compared to the unaffected elbow may be a fairly effective way to determine if the bursitis is septic or aseptic. In one study, 11 patients with septic elbow bursitis had skin temperature at least 2.2° C warmer (about 4° F warmer) on their affected elbows. In the same study, only 2 out of 35 patients with aseptic elbow bursitis showed such a large temperature differential at their elbows' skin surface.1
Imaging tests such as x-rays, MRIs, ultrasounds. Imaging tests are not usually needed to diagnose elbow bursitis. However, if it is unclear whether symptoms are caused by bursitis or another condition, a doctor may request an imaging test. MRIs are not effective in determining if bursitis is septic or aseptic.2