Example:
1. National Institute for Health and Care Excellence. Safeguarding adults in care homes. [Internet]. London, NICE, 2021 [cited 2021 Mar 1]. 102 p. [NG194]. Available from: http://www.nice.org.uk/guidance/ng189.
Selecting the PDF version will give you the number of pages of the report.
You can apply this method for guidelines and protocols from other health, government, professional and corporate bodies.
You need to include the following:
Author(s). Title of report. [Internet] if online. Place of publication, publisher; year of publication [cited year month day] if online. Pagination. Report series and number (if available). Available from: URL or DOI.