Hi there,
Unfortunately the most common cause of fluid buildup in the abdomen after
liver surgery is ascites, which is fluid in the abdomen that occurs when the liver isn't working very well. It may be that the liver she has left isn't enough to work well enough to keep that fluid out of her abdomen. The first thing that the doctors should do is make sure she is on a
water pill like furesomide (lasix) and
spironolactone (aldactone). These two pills help to make sure that extra water is removed from the body and may help the fluid that is building up in her abdomen. A low salt diet will also help her.
She may need continuing
paracentesis (removal of the liver from the abdomen). A procedure called a TIPS procedure (trans jugular intrahepatic portal shunt), where a shunt from the portal vein to the
inferior vena cava may help to reduce the amount of ascites your mother has, but there is a work of causing or worsening
encephalopathy.
It sounds like your mother needs to see doctors who have a bit more experience treating
liver failure. I'm a bit surprised if they really don't know what is causing the fluid, as (ascites) fluid in the belly after liver surgery is almost always due to the liver not working very well. I'd recommend making sure she goes to a university hospital that has experience with this.
I hope this answers your question. Please feel free to contact me if you have any further questions.