Free fluid in the pelvis means that a small amount of fluid has collected in the lower part of the abdomen, usually in an area called the pouch of Douglas, located between the uterus and the rectum. It is commonly seen on an ultrasound.
In women of reproductive age, a small amount of free fluid is often normal, especially after ovulation, when the follicle releases fluid, or during menstruation. In these cases, it does not need treatment.
However, free fluid can also be caused by a ruptured ovarian cyst, endometriosis, pelvic inflammatory disease, a ruptured ectopic pregnancy, an abscess or bleeding after trauma. Larger amounts of fluid, known as ascites, may be related to liver, heart or kidney disease, or to certain cancers, such as ovarian cancer. Free fluid is less expected after menopause, in men and in children, so it should always be evaluated in these cases.
Go to the emergency room right away if free fluid is found along with severe abdominal pain, dizziness, fainting, fever or a positive pregnancy test. Otherwise, follow up with your gynecologist or the doctor who ordered the test, who will interpret the result based on the amount of fluid, your symptoms and your medical history.