Final answer:
A volvulus on abdominal series or barium enema appears as a twisted and elongated section of the intestine, creating a 'whirl' or 'bird's beak' appearance on imaging studies.
Step-by-step explanation:
The classic appearance of a volvulus on abdominal series or barium enema is a twisted and elongated section of the intestine. This occurs when a segment of the intestine twists around itself, leading to a complete or partial obstruction. Visually, a volvulus appears as a 'whirl' or 'bird's beak' appearance on imaging studies.