Diagnostic performance and clinical applicability of salivary gland ultrasonography in primary Sjögren’s syndrome: a systematic review

Background Primary Sjögren’s syndrome (pSS) is a chronic systemic autoimmune disease characterized by lymphocytic infiltration of exocrine glands, leading to glandular dysfunction and important diagnostic challenges due to its heterogeneous presentation and the absence of a single gold standard test. Salivary gland ultrasonography (SGUS) has emerged as a promising non-invasive imaging modality for evaluating glandular involvement in pSS. Methods A systematic review was conducted to evaluate the diagnostic performance and clinical applicability of SGUS in pSS. A comprehensive search of PubMed/MEDLINE, Scopus, and Web of Science was performed up to March 2026. Original observational and diagnostic accuracy studies evaluating SGUS in patients with suspected or confirmed pSS were included. Two reviewers independently screened studies, extracted data, and assessed methodological quality using the QUADAS-2 tool, with disagreements resolved by consensus. Due to substantial methodological heterogeneity among studies, including variability in scoring systems, reference standards, and reported diagnostic parameters, a qualitative synthesis was performed. Results A total of 38 studies were included in the qualitative synthesis. SGUS demonstrated moderate-to-high diagnostic performance across studies, with improved reproducibility observed in investigations using standardized scoring systems, particularly the Outcome Measures in Rheumatology (OMERACT) definitions. Moderate agreement was observed between SGUS findings and minor salivary gland biopsy, although lower sensitivity was reported in early disease stages. Studies integrating SGUS into classification strategies suggested improved diagnostic accuracy. Emerging ultrasound techniques, including elastography and Doppler imaging, showed potential for enhanced assessment of glandular abnormalities, although evidence remains limited. Conclusions SGUS shows promising diagnostic utility as a non-invasive adjunctive tool in the evaluation of pSS, particularly when standardized scoring systems are applied. However, current evidence remains limited by heterogeneity in study design, scoring methods, and reference standards. SGUS should therefore be interpreted within a multimodal diagnostic framework rather than as a replacement for established diagnostic methods.