Hello! Thank you for the query. Yes, hematoma is most probable. And you should know that hematoma when left untreated can cause serious complication. Hematoma is a blood collection in the soft tissues. It is quite common after a surgery. Some parts of hematoma can get absorbed without any problems. But other part of hematoma gets infected, turns into an abscess. Abscess or inflammation in the area where something was stitched will cause weakness of this stitches and you will get back your hernia. Fluid accumulation (called seroma) is also possible. This fluid is produced by the peritoneum (a membrane which covers abdominal body from inside). If so, it is going to take weeks or even months for this fluid to stop being secreted. I suggest you to visit your surgeon and have it checked. Needle puncture might be necessary. Hope this will help. Regards.