A 14-year- old girl presents with lower abdominal pain which developed suddenly a day ago. The pain is over the whole lower abdomen but worse on the right. It was intermittent at first but is now constant and very severe. She feels unwell in herself with no appetite and vomiting. She now feels sweaty as well. She says her bowels opened normally the day before and they are normally regular. She has never had any previous episode of pain like this.

Her last menstrual period started 2 weeks ago and she has a slightly irregular cycle. She has never had any gynaecological or other medical problems in the past. Examination: On examination, she looks in pain and seems to find it difficult to get comfortable. Her temperature is 37.9°C, pulse 112/min and blood pressure 116/74 mmHg. She feels warm and well perfused. The abdomen is distended symmetrically with generalized tenderness, maximal in…