Home for the holidays, you made plans to have dinner at a friends' house. They are proud new parents and want you to meet their son, who was born in September. When you arrive for dinner, your friends are in a panic. The baby is crying and there is green vomit on the living room carpet. They explain that their son was just lying on the floor when he suddenly vomited and began crying. He had been fed a couple of hours ago and appeared to be fine. As the parents are removing their son's soiled clothes, they comment that the baby's abdomen looks larger than it did in the morning and that there are loud high-pitched sounds comming from the abdomen co-incident with the bouts of crying. You also notice a swelling in the left lower quadrant extending from above the middle of the inguinal ligament down to the upper left portion of the scrotum. You point this out to the mother. She reports that the swelling is warm to the touch and when she presses on it, the baby begins screaming in obvious pain.