Here is the design of a clinical trial:

Official Title: Impact of Emergency Physician-Performed Ultrasound for the Evaluation of Patients With Acute Abdominal Pain, Prospective Randomized Dual Centre Study

Included conditions:
- Abdominal Pain

Study Armgroups:
- {'label': 'Intervention', 'type': 'EXPERIMENTAL', 'description': 'Point-of-Care Ultrasound on top of diagnosis work-up', 'interventionNames': ['Diagnostic Test: Point-of-Care Ultrasound']}
- {'label': 'Control', 'type': 'NO_INTERVENTION', 'description': 'Usual diagnosis work-up without Point-of-Care Ultrasound'}

Interventions:
- {'type': 'DIAGNOSTIC_TEST', 'name': 'Point-of-Care Ultrasound', 'description': 'Abdominal clinician-performed Ultrasound', 'armGroupLabels': ['Intervention']}

Primary Outcomes:
- {'measure': 'Exact diagnostic rate', 'description': 'Comparison of the rate of exact diagnostic after clinical exam and biological results with point-of-care ultrasound (interventional arm) or without (control arm) according to the adjudication committee diagnostic (reference diagnosis).', 'timeFrame': "The reference diagnosis will be determined by an adjudication committee on the basis of an exhaustive analysis of the patient's file at Day 28"}

Please estimate the sample size based on the assumption: 
The study assumes a 0.05 alpha risk, 80% power, and a 5% attrition rate.
Sample size calculation
        According to Lindelius [7], a correct diagnosis has been reached in 56.8% of patients consulting to the ED for acute abdominal pain after the clinical exam and biological results. The hypothesis is based on an improvement of 30% of diagnostic accuracy by POCUS. Jang [10] demonstrated an improvement of diagnostic accuracy by 45% while Lindelius by 8% [7, 8]. A correct diagnostic rate of 57% is expected 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. A 5% attrition rate (patients randomized but presenting exclusion criteria) is expected; thus, 256 randomized patients are needed for this study.