Diagnostic performance of Doppler ultrasound for acute appendicitis: A systematic review and diagnostic test accuracy meta-analysis.

This systematic review and meta-analysis of diagnostic test accuracy evaluated the performance of Doppler ultrasound (DUS) in diagnosing acute appendicitis (AA) and its ability to distinguish complicated appendicitis (CAA) from non-complicated acute appendicitis (NCAA). The review was prospectively registered in PROSPERO (CRD42025641841), and a comprehensive search was conducted across PubMed, Web of Science, Scopus, and Ovid. Twenty-one studies were included. Study quality was assessed using the QUADAS-2 tool. Continuous quantitative parameters were synthesized using random-effects models (REML) while diagnostic performance data were analyzed through hierarchical models. For diagnosing AA, Spectral Doppler (SD) peak systolic velocity (PSV) showed a pooled sensitivity of 94 % [89-97] and specificity of 87 % [71-95], while SD resistive index (RI) showed a pooled sensitivity of 81 % [68-89] and specificity of 88 % [73-95]. Color Doppler (CD) achieved a pooled sensitivity of 82 % [70-90], specificity of 97 % [92-99], and AUC of 0.97 [0.95-0.98], with borderline evidence of small-study effects (Deeks' test p = 0.08). By contrast, evidence for discriminating CAA from NCAA was limited and heterogeneous, precluding reliable conclusions. DUS-particularly CD and SD-shows high accuracy when the appendix is visualized. Yet, because most studies excluded non-visualized cases, these estimates are inflated by spectrum bias and cannot be generalized to unselected populations. CD's high specificity (97 %) supports its role as a reliable rule-in tool in selected patients, but its true performance in routine practice remains unknown and requires prospective validation.