I don't have all the answers, but I do know that I have been told and read that free fluid in the cul de sac means you have cysts that are bursting that leaves the fluid. I have it too and was told it is pretty normal. I had it on 4 ultrasounds over the last 5 years and also had some when my laparoscopy was done last week. My docs act like it is nothing. Good luck
There is a small amount of fluid that naturally occurs in the abdomen. It is called "free fluid" because it is not contained in an organ nor is it contained in a cyst or mass. Its purpose, basically, is to lubricate the organs and tissues that rub and move against each other during the body's normal range of activities. I believe I have read that no more than 9 or 10 ml of fluid is normal.
However, there can be more fluid, and there are a number of causes of excess free fluid. <By the way, excess fluid is most commonly referred to as ascites.> Liver disease is one cause, and is probably the most common cause of excess fluid in the abdomen. Ovarian cancer is another cause, BUT simply having a benign cyst or cysts that have ruptured and spilled their contents can cause excess fluid.
So, if you doctor is not concerned, then you most likely have a small amount of free fluid, and no other signs that would give the doctor the idea that you have any serious conditions.