Final answer:
The nurse would find photographs of the site with date and time as the most beneficial initial documentation to help assess the worsening of an extravasation site.
Step-by-step explanation:
A patient reports worsening of the extravasation site. The nurse will find initial documentation of the extravasation most helpful. Among the listed options, Photographs of the site with date and time would provide the most comprehensive visual and temporal evidence of the extravasation progression and are helpful in assessing the extent of tissue damage over time. However, Quality of blood return before the infusion is also significant to consider, as it may indicate potential issues with catheter placement or function prior to extravasation. Nonetheless, photographs would give the immediate visual reference needed for comparison.