Abdominal Swelling in a Teenaged Girl

A 16-year-old girl presents to the local health department with 3months of abdominal pain and swelling that increase in intensity after meals, with early satiety and bloating. She also has had a recent increase in urinary frequency, with a need to get up once at night. She denies polydipsia, dysuria, or flank pain. She continues to have a healthy diet and soft stools twice daily. She has gained 4.5 kg in the previous 4 months without trying to do so; she does not mind the weight gain but is concerned that it is all around her abdomen