Post-traumatic acute abdominal pain

A 9-year-old female presented to the emergency department complaining of intense peri-umbilical pain with nausea and vomiting after a road accident. Physical examination revealed abdominal tenderness with a painful well-circumscribed mass in the lower abdomen. The haemodynamic state was stable. Ultrasonography showed a mobile hypoechoic mass with a moderate amount of free intraperitoneal fluid. An abdominal CT scan was performed. Axial images before and after intravenously administered contrast material are shown. What are the abnormalities seen in Figure 1? Figure 1 Abdominal CT scans obtained before and after intravenously administered contrast material. What do you notice in Figure 2? Figure 2 Abdominal CT scan with intravenously administered contrast material at a higher level. What is your diagnosis?