Why is napkin ring stricture called so?

The term "napkin ring stricture" refers to a specific type of narrowing in the gastrointestinal tract, often seen in conditions like cancer. It is called "napkin ring" because the shape of the constriction resembles that of a ring used to hold a napkin in place. This visual analogy highlights how the stricture encircles the intestinal lumen, leading to obstruction. The name helps clinicians easily identify and communicate about this particular presentation.