What it means
The organs in the belly sit inside a smooth lining called the peritoneum, with a thin film of fluid that lets them glide. Free fluid means there is enough fluid in that space to show on the scan, rather than inside an organ or a cyst. It tends to collect in the lowest spots, such as the pelvis. Reports describe it as trace, small, moderate or large.
When it matters
A small amount in the pelvis is common and normal in women of reproductive age, often around ovulation or a period. Larger amounts, fluid in men, or fluid after an injury get a closer look. Causes include inflammation, infection, bleeding, a burst ovarian cyst, and liver, heart or kidney conditions. Doctors weigh it with your symptoms and blood tests, and sometimes a sample is drawn off and tested.
Questions to ask your doctor
- Is this amount of free fluid normal for me?
- Does it look like simple fluid, or could it be blood or infection?
- Should it be checked again on a later scan?
