A nurse is caring for a post-operative patient recovering from abdominal surgery with a Jackson-Pratt (JP) drain in place. Which assessment finding requires immediate nursing intervention?

The drainage decreased from 40 mL to 25 mL over the last 24 hours

The JP bulb is fully expanded and no drainage has collected for several hours

The JP bulb is fully compressed and slowly filling with serosanguineous fluid

The patient reports mild pulling sensation at the drain insertion site