What is a seroma? A seroma is an accumulation of fluid in a tissue or organ that can occur after surgery, or sometimes after an injury such as blunt trauma. The fluid, called serum, leaks out of nearby damaged blood and lymphatic vessels. Cells are typically present in the fluid, which is normally clear. Seromas can occur after a number of different types of surgeries, especially those that are extensive or involve significant tissue disruption. These include hernia repairs, significant plastic surgeries such as breast augmentation or reconstruction, abdominoplasties (tummy tucks), and surgeries performed for breast cancer. Seroma formation may be associated with an increased risk of infection and breakdown of the surgical site. Surgical drain tubes with bulb suction devices are used after some surgeries to help reduce the risk of seroma formation. These allow for monitoring the volume of fluid leakage, and once drainage becomes minimal, the drains are removed. Seromas can form shortly after surgery if drains are not used, and they may also occur after removal of a drain. Small seromas often resolve on their own, although left untreated, they can calcify, forming hard knots. Larger seromas often require aspiration (removal of fluid), generally accomplished with a needle. Seromas that become infected may require antibiotic therapy and, on rare occasions, surgery may be necessary to treat a seroma. Seromas can interfere with healing of a surgical site and may require drainage if they are large. An infected seroma can develop into an abscess, indicating the presence of serious infection. Seek immediate medical care (call 911) if you, or someone you are with, have symptoms that suggest serious infection is present, such as pus draining from the surgical site, high fever (higher than 101 degrees Fahrenheit), severe pain, rapid heart rate (tachycardia), or if the surgical wound opens up significantly. Seek prompt medical care if you notice a lump near the surgical site, if fluid starts to drain from the surgical site, if there is redness, warmth or swelling, or if the site feels tender. Also seek prompt medical care if you have a seroma that is being monitored and you notice an increase in its size, or if fluid drainage, redness, warmth, swelling or tenderness develop at the site.