Impact of emergency physician-performed ultrasound for the evaluation of patients with acute abdominal pain, prospective randomized dual Centre study: study protocol for a diagnostic trial

Background Abdominal pain is frequent in patients consulting in emergency departments. The aim of this study is to determine the diagnosis efficacy of point-of-care ultrasound (POCUS) in patients consulting in the ED for acute abdominal pain by comparing the rate of exact diagnostic between the two arms (with or without POCUS), according to the index diagnostic established by an adjudication committee. Methods It is a randomized, controlled, open and interventional study in two emergency departments. The included patients will be adults admitted for acute abdominal pain. Exclusion criteria will be a documented end-of-life, an immediate need of life-support therapy and pregnant or breast-feeding women. Patients will be randomized in intervention (POCUS) or control groups. POCUS will only be performed by trained physicians and will be added to the diagnosis procedure in the intervention group. In the control group, the diagnosis will be established after clinical examination and reception of biological analysis results. In the interventional group, the diagnosis will be established after a clinical exam, biological analysis reception and POCUS. An adjudication committee will review all data from case report forms and will determine the index diagnosis which will be used for the analysis. The primary endpoint will be the comparison of the rate of exact diagnostic between the two arms according to the adjudication committee diagnostic. Secondary endpoints will be the comparison between the two groups for diagnostic delay, duration of ED stay, diagnostic performances for non-specific abdominal pain and hospitalization rate. The primary endpoint will be compared between the two groups using a mixed model taking into account the recruiting centre. Delays will be compared by a mixed linear generalized model. Diagnostic performances will be estimated with their 95% confidence intervals. For a correct diagnostic rate of 57% in the control group and 74% in the intervention group with a 0.05 alpha risk and a 80% power, 244 patients will be required. Discussion POCUS diagnostic abilities have been mainly demonstrated in monocentric studies but the level of evidence of its diagnostic efficacy remains controversial in particular in Europe. The aim of this study is to address this question with a rigorous methodology. Trial registration ClinicalTrials.gov NCT04912206. Registered on June 3, 2021.