PRISMA 2020 distinguishes records (database entries) from reports (published documents), explicitly splits identification into database-and-register and other-methods branches, supports variants for review updates and living reviews, includes a separate sub-node for reports not retrieved, and standardizes the reasons-for-exclusion block at the eligibility phase. PRISMA 2009 used 'records' loosely throughout, pooled identification sources, and did not distinguish reports from records.

The PRISMA flow diagram is a standardized four-phase visual that documents how records progress through a systematic review: identification (database searches and other methods), screening (title and abstract), eligibility (full-text review with reasons for exclusion), and included (final set of studies feeding synthesis). The diagram is required by all journals endorsing PRISMA reporting standards and provides transparent accounting of every record entering the pipeline and every report excluded at the full-text stage.

The current standard is the PRISMA 2020 flow diagram, published in BMJ in March 2021. It supersedes the PRISMA 2009 diagram. The 2020 template distinguishes records from reports, splits identification into a database-and-register branch and an other-methods branch, and includes optional variants for review updates and scoping reviews (PRISMA-ScR). Reviews published in 2026 should use the 2020 diagram.