Specific Rules #3 for Edition (required) for the Volume for Individual Volumes With a Separate Title and Separate Authors/Editors Vancouver Style: First editions

If a book does not carry any statement of edition, assume it is the first or only edition.

Use 1st ed. only when you know that subsequent editions have been published and you are citing the earlier one.

Según:

Citing Medicine: The NLM Style Guide for Authors, Editors, and Publishers [Internet]. 2nd edition. Chapter 2: Books

Related:

General Rules for Edition (required) for the Volume for Individual Volumes With a Separate Title and Separate Authors/Editors Vancouver Style

Specific Rules #1 for Edition (required) for the Volume for Individual Volumes With a Separate Title and Separate Authors/Editors Vancouver Style: Abbreviation rules for editions

Specific Rules #2 for Edition (required) for the Volume for Individual Volumes With a Separate Title and Separate Authors/Editors Vancouver Style: Non-English words for editions

Specific Rules #3 for Edition (required) for the Volume for Individual Volumes With a Separate Title and Separate Authors/Editors Vancouver Style: First editions

Examples for Edition (required) for the Volume for Individual Volumes With a Separate Title and Separate Authors/Editors Vancouver Style