As PP have said CD10 is the day of your cycle and your U/S results show a very normal uterus and lining and you ovaries have multiple follicles. There can be a small amount of fluid in the pouch of douglas that comes from the ovary as the egg is released. A large amount may be from a ruptured cyst. No fluid is good. Fluid or blood in the Pouch of Douglas may be a feature of a tubal pregnancy
that is aborting or that has ruptured. In the Pouch of Douglas, free fluid may emanate from a ruptured or leaking ectopic gestation and/or from a ruptured corpus luteum.