[La Profe_1]

When I traveled with a young Dominicana who needed surgery and received it in the US, Immigration stapled a white form at the back of her passport.

That white form was collected at the gate as she boarded the plane.

As a Dominicana, she obviously needed a visa to enter the US. I am not sure how it works with Schengen visas, but you would know if the form was placed in the passport and subsequently collected.