A Source Document (SD) is the original record where clinical trial data are first recorded, such as medical charts, lab reports, imaging results, diaries, or device outputs.
Source documents provide the basis for verifying the accuracy of data entered into case report forms and electronic systems. They must be complete, legible, attributable, and maintained with appropriate version control and access safeguards. Monitors and auditors use source documents to confirm informed consent documentation, protocol compliance, and endpoint validity. Strong source documentation practices protect data integrity and support defensible results during inspections.