How to Make a PRISMA Flow Diagram for a Systematic Review

The PRISMA flow diagram is the figure that tells a reviewer your screening was systematic and reproducible. Here is how to build one that holds up — and how to draw a clean conceptual framework too.

What a PRISMA flow diagram is for

PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) is the reporting standard for systematic reviews. Its flow diagram documents exactly how you went from thousands of search hits to a handful of included studies. Reviewers require it because it makes your screening reproducible and exposes selection bias: a reader can see how many records you excluded and why. A review without a credible PRISMA flow is hard to publish.

The four stages and the numbers each needs

The PRISMA 2020 flow moves through four stages. Track these counts as you screen — reconstructing them afterwards is painful:

• Identification. Records found in each database (state the number per source), plus records from other methods (citation searching, registers). Then duplicates removed before screening.
• Screening. Records screened by title/abstract, and records excluded at this stage.
• Eligibility. Full-text reports sought and assessed, reports not retrieved, and full texts excluded — with reasons (wrong population, wrong design, no outcome of interest). Reviewers care most about these reasons.
• Included. Studies included in the review, and reports included in any meta-analysis.

Every number must reconcile: records in minus exclusions equals records out, at each step. Mismatched arithmetic is a common reason reviewers send a review back.

Practical tips for a clean PRISMA figure

• Log exclusion reasons during full-text screening, not at the end. You will need the breakdown for the eligibility box.
• Report per-database counts in the identification box so the search is reproducible.
• Keep boxes parallel and arrows one-directional (top to bottom). Clarity is the whole point of the figure.
• Match the diagram to the text — the included-studies count in the figure must equal the number you analyse.

Drawing a conceptual framework figure

The other diagram most papers need is the conceptual framework — the visual of your research model. A few rules make it readable:

• One box per construct, one arrow per hypothesis. The figure should map exactly onto your hypotheses.
• Left-to-right causal flow — predictors on the left, outcomes on the right, mediators between.
• Show moderators as arrows pointing at other arrows, not at boxes.
• Label paths with hypothesis numbers (H1, H2) so readers can connect figure and text.
• Resist clutter. If the figure needs a key to be understood, it is too complex.

Export it properly

Journals want crisp figures. Export at high resolution (vector formats like SVG or PDF where allowed, or 300+ dpi PNG), check it is legible in greyscale, and confirm text stays readable at the column width the journal uses. A diagram that pixelates in production undoes the work that went into it.

Final thought

Research diagrams are arguments in visual form. A PRISMA flow argues that your review was rigorous; a conceptual framework argues that your model is coherent. Build them with the same care you give the prose. DiagramCloud handles the layout so you can focus on getting the logic and the numbers right.