Dear Maddie,
Ascites means fluid in the abdomen. It is not really understood why ascites occurs. there are two main theories : a tumor actually secretes fluid or causes the lining of the abdomen to secrete fluid. The second theory is only relevant to cancerous tumors which is that ascites develops when tumor cells spread and blocks the pores in the
diaphragmDiaphragm
Diaphragm and lungs
Diaphragmatic hernia repair - series
The diaphragm ( the muscle boundary between the abdomen and the chest) which prevent the normal absorption of fluid in the abdomen.
Ascites can also be caused by medical problems such as heart failure or cirrhosis of the liver.
I n your situation, the most common possibility is a benign ovarian fibroma. these benign tumors classically can cause ascites and even fluid in the chest. endometriosis is not usually associated with ascites.
I agree that surgery is the appropriate next course. I hope all goes well
best wishes