As other physicians have said here, seromas or not uncommon after surgery. Those of us with low rates of postoperative seromas usually leave drains in following abdominal surgery for a longer period of time. Once a seroma forms, percutaneous aspiration is the usual therapy as you've described. It is also true that your body contributes to seroma resolution by absorbing the fluid over time. Sometimes chronic seromas can form where the wall of the seroma becomes thicker and better absorption does not happen. This occurs in a minority of cases.
If your physician had aspirated your fluid collection and you now have no clinical evidence such as bulging or apparent fluid below the skin, it is likely that the seroma is either completely resolved or on its way to being so. If however you have reaccumulation of the fluid which is also common, further aspiration may be necessary. The fluid collection, unto itself, is unlikely dangerous to you unless it gets infected. Things to watch for would be a fever, redness, or increased pain.
Without those signs, it is very unlikely that she need to worry about anything. In fact if it does not appear that you have excess fluid reaccumulated in that area, it is very unlikely that you have a residual problematic seroma. No further tests would be required aside from examination by your plastic surgeon on a normal scheduled basis.
