Value of ultrasound-guided synovial biopsy for the diagnosis of infectious arthritis.

To determine the value of ultrasound (US)-guided synovial biopsy for the diagnosis of infectious arthritis that could not be detected by other modalities.This descriptive study was conducted among 37 patients with arthritis (3 with shoulder arthritis, 2 with elbow arthritis, 7 with wrist arthritis, 15 with hip arthritis, 4 with knee arthritis, and 5 with ankle arthritis) who underwent US-guided synovial biopsy at Hanoi Medical University Hospital for the diagnosis of infec-tious arthritis that could not be detected by infection laboratory tests, imaging, and/or joint fluid culture. The results of US-guided synovial biopsy were positive for infectious arthritis when those of pathologi-cal analyses, bacterial cultures, and/or polymerase chain reaction test for tuberculosis were positive. The final diagnosis established when the patients were discharged from the hospital was compared with the US-guided synovial biopsy results to calculate the sensitivity and specificity for the diagnosis of infectious arthritis.The median age of the patients was 60 years (range: 22-79 years), and two thirds were women. Infectious arthritis was determined as the final diagnosis in 18 patients. There was no significant difference in the infection laboratory test results, synovial thickness, or magnetic resonance imaging features apart from soft tissue abscess between the infectious and non-infectious arthritis groups (P > 0.05). The US-guided synovial biopsy results were positive in 17 patients. Compared with the sensitivity and specificity of the final diagnosis, those of the US-guided synovial biopsy results for the diagnosis of infectious arthritis were 94.4% and 100%, respectively. The Numerical Rating Scale score was ≤3 in most patients. There were neither vascular nor neurologic complications among the patients.Imaging features and laboratory test results are non-specific for infectious arthritis. US-guided synovial biopsy is a well-tolerated, safe method that has a high value for the diagnosis of infectious arthritis. This modality should then be recommended for patients with unclassified arthritis.