How can I tell if it's a seroma vs hematoma vs ruptured sutures 7 months post-op abdominoplasty? (photos)

I’m a 35 yr female, 5’3” 146 lbs. I’ve had two children 10 years apart. After my last child I had full abdominoplasty, with lipo 360 and diastaisis recti repair. I’ve had this bulge at the top of my abdomen that appeared 4 days post op. I’m 7 months post op and I was hoping it was something my body could reabsorb. My surgeon wants to do surgery…How can I tell if it’s a seroma vs hematoma vs ruptured sutures on my abdomen wall?