Post-op seromas

I am shceduled for revision surgery 3/7/2008 and I wondered if  anyone out there has had problems with seromas since losing weight.   I lost 100# with a VBG and am now  having an RNY.  Since I lost weight every surgery since I develop a seroma.  Except when I had a hernia repair and the surgeon just kept  irrigating the wound.  He said that after weight loss you have an oily type substance and with irrigation it is removed.  Has anyone out there heard anything similar to this?