Hi Caesar,
Ascites is collection of fluid in the abdomen (
peritoneal cavity). Most common cause of ascites is usually
liver disease. If you have an history of Liver disease, it could lead to ascites. In view of history of 20 years, I am of the opinion that it could be obesity tummy (fat accumulation).
If you have associated
jaundice (yellowish discoloration of skin, sclera), itching or
vomiting or coughing blood or passing blood in stools - then it could be ascites secondary to liver disease(Short duration only, 20 years duration is not possible).
If it were to be other causes of ascites, you need to look to lower limb swelling, facial swelling ...
I can assure you from the information provided, it is not ascites.
Hope I have answered your query. If you have any further doubts, I will be happy to help.