Surgical drain
A tube placed during surgery to remove fluid or blood from the operative site.
Drains (Jackson-Pratt, Penrose, chest tubes) are placed at the end of surgery to evacuate post-op fluid collections. They're typically removed when output drops below a threshold over 24 hours.
What this means for you: don't fly home with a drain still in place. Confirm drain removal is part of the discharge plan.
What a term means for you depends on your own reports. Ask your treating doctor, or send your reports for a free review.