Per AMBOSS, Bowel obstruction → Diagnostics → Acute abdominal series
“A series of radiographs of the abdomen and chest used to detect pneumoperitoneum and/or bowel obstruction in patients with acute abdominal pain. Consists of two abdominal x-rays (in supine position and upright position) and a chest x-ray (in upright position).”
I would change upright KUB to “acute abdominal series” which hyperlinks to the AMBOSS add-on. I would also add in the Extra field: “Acute abdominal series = 3 x-rays; upright CXR, upright ABD, and supine ABD”