Paediatricscommon
A 14-year-old boy presents with sudden severe lower abdominal pain that woke him from sleep two hours ago, accompanied by two episodes of vomiting. He is pale and distressed and walks slowly into the cubicle. His temperature is 36.9°C and pulse 104/min. The abdomen is soft with mild suprapubic tenderness, no guarding, and normal bowel sounds. Which one of the following is the most important next step in assessment?