An infant male is presented on the second day of life with a large bilious emesis. He had been "spitty" for a day and had yielded 15 ml of greenish gastric aspirate at birth. He had not passed meconium for the first 36 hours of life. He was born at term weighing 3.5 kg. Physical Exam: VS T 37.2 (rectal), P 125, R 30, BP 75/55, weight 3.4 kg. He is an active hungry infant with a moderately distended abdomen. Bowel sounds are very active but not obstructive in nature.
No organs or abdominal masses are appreciated and no herniae are present. His anus is patent. An abdominal series revealed large dilated loops of bowel but no air in the rectum. What tests are recommended further? What can be the diagnosis?
