How do I trace excluded studies into a PRISMA 2020 flow diagram with reasons?

Trace each excluded record by assigning it to one PRISMA 2020 flow stage and recording the first screening criterion it failed, then build the diagram so every stage count reconciles with the screening log. PRISMA 2020 provides flow diagrams for transparent reporting of what studies were found and included, and the Cochrane Handbook covers documenting searches and managing records during study selection.

Build the trace in four steps

1. Fix the stage definitions before screening. Label each log row with the stage where the record left the review: duplicate removal, title and abstract screening, full-text retrieval, or full-text eligibility. The expected result is one stage value per excluded record, so no record is counted twice.
2. Record the first-failure reason at the point of exclusion. When a record fails several criteria, log the first criterion it failed in the screening sequence and keep the others as secondary notes. The expected result is one primary exclusion reason per record, which keeps the exclusion boxes additive.
3. Reconcile counts against the log. Sum records entering each stage, subtract records excluded at that stage, and compare the remainder with the number carried to the next stage. The expected result is that each stage total equals the previous remainder, and any gap points to a record with a missing or duplicated stage value.
4. Populate the diagram from the reconciled log. Place stage counts in the flow boxes and list the first-failure reasons with their counts in the exclusion boxes beside each stage. The expected result is a diagram whose exclusion boxes sum to the records excluded at that stage.

Where reconciliation usually breaks

Records excluded during full-text retrieval belong to a different stage than records excluded for ineligibility after the full text was assessed. Keep those two groups separate so the retrieval box and the eligibility box each match their log rows. Duplicate removal is also a stage: count duplicates there and remove them from later screening totals.

When a count does not reconcile, treat the discrepancy as unresolved and check the log for records with a blank stage, a blank reason, or two stage entries before adjusting the diagram. Name the search sources and documentation practices in the methods section, following the Cochrane Handbook's coverage of documenting searches and managing records.