First of all POD fluid can vary from very Little to quite a significant quantity depending on different conditions. More over if you have additional symptoms like pain excessive bleeding etc then the whole set of signs and symptoms can be labelled as PID. A few blood tests also should be done . Any ways PID is curable and your doctor will give you suitable antibiotics Repeat scan has to be done to check if the fluid is no more. Don't worry your gynaecologist will take care of you.