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Is a normal ESR enough to rule out septic arthritis?

Three Part Question

In [adults presenting to the ED with an acute hot joint] is a [normal ESR] sensitive enough [to rule out septic arthritis]

Clinical Scenario

A 48 year old with a presents with a one day history of red, swollen right knee. On examination she is febrile, has decreased range of movement and a left knee effusion. You order bloods and the ESR comes back within normal range. You wonder what benefit ESR gives in ruling out SA? [1]

Search Strategy

Multi-file search using OVID – Medline (1950-2008), Embase (1980-2008), CINAL (1982-2008), Cochrane ({[exp Infective Arthritis OR hot OR septic OR septic] AND [ exp Blood Sedimentation OR exp C - reactive protein OR exp laboratory techniques and procedures OR OR OR inflammatory]}) Limited to Humans, English Language and Adults

Search Outcome

The following number of articles were identified from each of the databases: Medline 530 citations, Embase 301 citations, CINHAL 5 citations, Cochrane 7 citations. Duplicates and irrelevant titles removed from 843 articles leaving a total of five relevant articles.


For a test to rule out disease it must be 100% sensitive. The sensitivity of ESR was high in all three studies that documented it but not sufficiently high to rule out SA. [1-3] This was supported by two studies that noted no elevation in ESR in cases of known SA. [2, 7] The positive and negative LR found in two studies were neither high nor low enough respectively to predict disease. [1, 4] In the recent systematic review, “Does the Adult Patient Have Septic Arthritis?” ESR was noted along with WBC to have little diagnostic power for changing the pretest probability for septic arthritis, this being mostly due to its low specificity.[1] However, there may be some use of ESR in combination with WBC and jWBC as their combined sensitivity is 100% . [2] If there is no elevation of these three tests, this may be sufficient to rule out septic arthritis when the clinical picture is uncomplicated. As with the WBC and joint aspirate WBC (j WBC), the value of ESR in the presentation of the acute hot joint is as an adjunct to a clinical suspicion of SA. Synovial Fluid and blood culture analysis should be performed irrespective of inflammatory indices in the case of high clinical suspicion of SA [5].

Clinical Bottom Line

ESR is neither sensitive nor specific enough to rule in/out septic arthritis. *Newman A Classification- diagnosis of SA based on the presence of bacteria on synovial culture **Imperfect Gold Standard –gram stain (sensitivity 29-50%) and culture (sensitive-82%) [1] References 1. Margaretten ME. Does the Adult Patient Have Septic Arthritis? JAMA 2007; 297(13):1478-1488 2. Li SF. Diagnostic utility of laboratory tests in septic arthritis. Emergency Medical Journal. 2007; 24:75-77 3. Li SF. Laboratory Tests in Adults with Monoarticular Arthritis: Can They Rule Out a Septic Joint? Emergency Medical Journal. 2004; 11(3):276-280 4. Peters RHJ. Bacterial Arthritis in a District Hospital. Clinical Rheumatology. 1992; 11(3):351-3555 5. GuptaMN. Sturrock RD, Field M. Prospective comparative study of patients with culture proven and high suspicion of adult onset septic arthritis. Annals of Rheumatological Diseases.2003, 62:327-331 6. Jeng GW, Wang CR, Liu ST, et al. Measurement of synovial tumor necrosis factor-alpha in diagnosing emergency patients with bacterial arthritis. American Journal of Emergency Medicine. 1997;15:626-629 GuptaMN. Sturrock RD, Field M. Prospective comparative study of patients with culture proven and high suspicion of adult onset septic arthritis. Annals of Rheumatological Diseases.2003,62:327-331 7. Soderquist B. Bacterial or Crystal –associated Arthritis? Discriminating Ability of Serum Inflammatory Markers. Scandinavian Journal of Infectious Diseases. 1998;30:591-596