A pediatric client is admitted to the unit with failure to thrive. The mother states that the child has been "spitting up" and excessively crying immediately after every bottle. What diagnostic test will the nurse anticipate to confirm a diagnosis?

Upper gastrointestinal series to determine structural abnormalities from gastroesophageal reflux

Biopsy of small intestine mucosa to rule out celiac disease

Ultrasound to assess for presence of pyloric stenosis

Lower gastrointestinal series to assess for an intestinal blockage