DIAGNOSTIC YIELD OF LABORATORY AND IMAGING INVESTIGATIONS IN FEBRILE CHILDREN: IMPLICATIONS FOR RESOURCE USE

Background: Fever is one of the most common presenting symptoms to the District General Hospital (DGH) Paediatric Assessment Unit (PAU) and a frequent reason for hospital admission, yet the diagnostic yield of many investigations is low, particularly in viral illnesses. NICE NG143 recommends targeted testing based on risk stratification. Inflammatory markers can be useful for identifying serious infections in ambulatory settings, whereas white blood cell counts are less reliable for ruling in or out serious infection; different cut-off values are recommended depending on clinical intent. Blood cultures done beyond 48 hours of persistent fever without new clinical instability have limited diagnostic yield, with a substantial proportion being false positives. Chest X-ray (CXR) in febrile infants without respiratory symptoms rarely detects pathology, suggesting potential overuse. Rapid viral testing in the emergency department has also been associated with reduced use of unnecessary imaging. These low-yield investigations consume considerable hospital resources, including staff time for performing and reviewing tests, consumables, and bed occupancy while awaiting results, in addition to increasing patient discomfort and potentially delaying care. We audited the diagnostic yield of laboratory and imaging investigations in febrile children presenting to a DGH PAU. Method: We retrospectively reviewed all febrile presentations to PAU over a 2-month period. Data collected included demographics, NICE stratification, investigations performed, and results (FBC, CRP, blood/urine cultures, CXR, LP, viral swabs). The diagnostic yield (proportion of positive results) was calculated for each test. Results: 144 children were included. Blood tests were done in 30.6% of children: elevated CRP in 47.7%, elevated WBC in 34.1%, and positive blood cultures in 6.8%. Urine testing was performed in 18.1%, positive in 11.5%. CXR was performed in 16%, with no findings of pneumonia. LP was performed in 2.8%, with no positive results. Viral swabs were performed in 59%, with 51.8% positive. Overall, the majority of laboratory and imaging investigations did not yield clinically actionable results. For example, 23 CXRs were performed without detecting a single pneumonia. This highlights substantial resource use, including staff time, consumables, and potential delays, relative to the diagnostic benefit. Conclusion: The audit shows that many investigations in febrile children have low diagnostic yield, representing potentially inefficient use of hospital resources. Targeted testing based on NICE NG143 risk stratification could reduce unnecessary investigations, improve patient experience, and optimize resource use. Reinforcing guidelines and education, followed by a re-audit, is recommended to assess impact.