Why do some doctors use drains after a tummy tuck?

I have been using progressive tension sutures for nearly 20 years, so it is not a newer method. I found early on that the amount of fluid in the drains is diminished but it is not zero. There are other benefits to the PTS method, and the drains can come out earlier than without. 

Thank you for sharing your excellent question.  The decision to use drains, quilting stitches, or both is a decision best made by your surgeon assessing the relative risk of you forming a discrete fluid collection.  In my practice I favor drain placement in patient's having more extensive tummy tucks and having liposuction performed at the same time.  Hope this helps.