What is seroma ?? is this common after umbilical hernia surgery ??

It is not : Common but it happens it is a collection of serous fluid that the body will eventually absorb in moSt cases. Occasionally the need to be drained

Collection of fluid: A seroma is a collection of fluid (serum). The serum is the liquid part of your blood (as opposed to the cells) and is similar to the fluid that is inside a blister. Seromas can occur after any surgery and can resolve without treatment although sometimes the doctor will draw out the fluid. If it is causing a lot of discomfort, return to the doctor for treatment. DO NOT TRY TO DRAIN IT ON YOUR OWN.