Ascites is usually caused by impaired circulation to/from the liver, which is in turn caused by liver disease that physically alters the organ (cirrhosis, cancer
, etc.) or an obstructing growth such as cancer
of the abdoinal organs.
So if you have a SUDDEN bloat like that, put ascites way down on your list of worries and rest assured anything but the mildest degree would almost certainly be discovered on the first exam, no matter what the underlying cause.