How should an abdominal mass in a neonate be evaluated?

Supine and upright or decubitus abdominal radiographs should be obtained. If the images show obstruction, an upper gastrointestinal series or a barium enema should be performed. If the images are negative, an ultrasound should be performed to identify the organ of origin or confirm hydronephrosis. A CT may be indicated in the case of a solid mass.