contextual clues lead us to assume that the operation that the American refers to is-what? in the story Hills Like White Elephants by Ernest Hemingway

One of the
most telling clues that the operation is an abortion comes toward the end when the man
says,

"You've got to realize that I don't want you to
do it if you don't want to.  I'm perfectly willing to go through with it [the pregnancy] if it
means anything to you."

And later he says,

"But I don't want anybody but you.  I don't want any one else. 
And I know it's perfectly simple."

The setting
itself also gives clues that the couple is talking about a decision between productivity and
barreness.  On one side of the train station are fields of...