My mothers abdomen is very round(a ball like ) and large its just like she is pregnant but she isn't and some times it get bigger what's the problem?

Liver disease: Can cause a fluid build up in the abdomen that can make an older person look pregnant--it's called ascites. She should go to the doctor to have basic blood work done to see if her liver is not functioning as well as it should. This can be a life threatening issue if not solved quickly. A history of hepatitis puts her at higher risk.