Twenty five studies (n = 3,838) were included in the review: two were classified as Level 1; five as Level 2; 13 as Level 3; and five as Level 4.
For the identification of haemoperitoneum using FAST protocol (imaging for intra-peritoneal fluid only) the pooled estimate of sensitivity was 80 per cent (95% CI: 76, 84) and specificity 96 per cent (95% CI: 95, 97). The pooled estimate for positive LRs was 22.9 (95% CI: 17.2, 30.5) and for negative LRs was 0.2 (95% CI: 0.16, 0.25).
For the identification of any IAI using FAST protocol (imaging for intra-peritoneal fluid only) the pooled estimate of sensitivity was 66 per cent (95% CI: 60, 71) and specificity was 93 per cent (95% CI: 92, 95). The pooled estimate for positive LRs was 9.8 (95% CI: 7.9, 12.1) and for negative LRs was 0.37 (95% CI: 0.32, 0.43).
For the identification of any IAI using imaging for both intra-peritoneal fluid and solid organs the pooled estimate of sensitivity was 82 per cent (95% CI: 78, 86) and specificity was 97 per cent (95% CI: 96, 97). The pooled estimate for positive LRs was 24.5 (95% CI: 19.0, 31.6) and for negative LRs was 0.18 (95% CI: 0.15, 0.23).
No heterogeneity was identified in any data set for sensitivity and specificity. Heterogeneity was present in all three data sets in both positive and negative LRs.
Sensitivity analyses indicated that test performance decreased when only studies of higher methodological quality were included in analyses.