Incidence of intra-abdominal injury after blunt abdominal trauma with negative CT scan: a systematic review and meta-analysis

BACKGROUND: Missed intra-abdominal injuries (IAI) after blunt abdominal trauma (BAT) with a negative CT scan are rare, but incidence estimates vary across populations and over time, leading to heterogeneous practices regarding observation and discharge. The aim of this study is to synthesize available evidence to estimate the incidence of IAI among patients with BAT and a negative CT scan and to examine how different characteristics influence this risk. METHODS: Systematic searches were conducted in MEDLINE, EMBASE, CENTRAL, and LILACS from inception to May 12, 2025, without language restrictions, and supplemented with WoS, trial registries and grey literature sources. Eligible studies included cohort, cross-sectional, case-control studies, or randomized trials evaluating patients of any age with BAT who underwent CT with negative findings for IAI. Emergent procedures and hemodynamic instability were exclusion criteria. Screening and study selection were performed independently by two reviewers. Duplicate and independent data extraction was conducted. Reporting followed PRISMA guidelines and quality was assessed using the Joanna Briggs Institute tool. Pooled incidences were estimated using random-effects meta-analysis. The primary outcome was the incidence of IAI in patients with negative CT scans, and subgroup and sensitivity analyses were performed to assess heterogeneity and robustness. RESULTS: = 62.8%) and largely explained by patient characteristics and CT technology. Subgroups with high-risk clinical features had a higher incidence (1.03%; 95% CI, 0.31-2.12%) than unselected trauma cohorts (0.22%; 95% CI, 0.12-0.35%, p = 0.01). Older CT technology showed a higher incidence (0.69%; 95% CI, 0.25-1.33%, compared with MDCT (0.26%; 95% CI 0.14-0.42%, p = 0.05). Sensitivity analyses with GLMM confirmed the robustness of our findings. CONCLUSIONS: In patients with blunt abdominal trauma and a negative CT scan, the incidence of intra-abdominal injury is exceedingly low (0.34%). These findings provide robust, contemporary evidence to inform clinical decisions regarding the need for in-hospital observation and support consideration of early discharge in most patients, while recognizing that individuals with high-risk clinical features may warrant closer monitoring.