Diagnostic utility of abdominal radiography in emergency departments with high guideline compliance: a retrospective cohort study.

PURPOSE: Abdominal radiography (AXR) remains widely used in emergency departments (EDs) despite concerns about diagnostic performance, often attributed to inappropriate use. We evaluated appropriateness, diagnostic yield and 48-hour abdominopelvic CT utilisation in two Scottish EDs with high Royal College of Radiologists (RCR) iRefer adherence. METHODS: Retrospective multi-centre cohort study of 866 adults (median age 65 years, 49.5% female) undergoing AXR during ED attendance at two Scottish acute hospitals in 2024. Requests were classified against RCR iRefer (2017) criteria. Primary outcomes were RCR compliance and CT utilisation within 48 h; secondary outcomes were AXR yield by compliance, CT positivity by AXR result, AXR-CT concordance, and disposition. RESULTS: RCR compliance was 88.3%. Despite this, 67.9% of AXRs were normal and 35.6% of patients underwent CT within 48 h. Among patients proceeding to CT, clinically significant pathology was identified after 80.0% (136/170) of normal and 95.7% (132/138) of abnormal AXRs. Compliant requests had higher AXR yield (33.6% vs. 20.8%, p = 0.01) but compliance did not predict CT utilisation (p = 0.67). CT provided discordant or additive information beyond AXR in 12.7% and 28.6% of paired examinations, respectively. Of patients undergoing CT, 98.1% were admitted irrespective of result. CONCLUSIONS: Exemplary guideline adherence did not overcome AXR's diagnostic limitations. A normal AXR did not exclude significant pathology, and abnormal AXRs frequently required CT for characterisation. These findings support prospective evaluation of direct-to-CT pathways for selected acute abdominal presentations, including patient-safety, workflow and economic outcomes.