Seroma or scar tissue? (Photo)

The story and the photos would suggest seroma.  The treatment for this is multiple visits to your surgeon's office over the next few weeks to get this drained.  If it is not drained, sometimes a surgical procedure is needed to remove the fluid collection.  You are likely going to need to follow up with a plastic surgeon stateside and have to pay out of pocket for these treatments.Best of luck!
Dr. SubbioBoard-Certified Plastic SurgeonNewtown Square/Philadelphia, PA

Patients who have postoperative complications are well served to follow up with their physician who treated them.  It is very helpful to  see your physician regularly in postop to watch for signs of atypical recovery.  Management of seroma is frequently done by physical exam and aspiration of any fluid if it is noticed. During the operation if the Scarpa's fascia is preserved this has been shown to dramatically reduce postoperative seroma formation. 

Who knows best is your surgeon, no matter if he is abroad or not, if he says this is seroma then it is very likely it is; actually looks likely it is; seromas are very rebellious sometimes, specially with tummy tucks, moreover if they have associated liposuction at the adjacent areas.Their diagnosis is by simple palpation, no radiology required, come on... it is a matter of just having a bit of surgical experience and feel the liquid or see the waves when tapping on the skin; anyhow I'd rather follow your original surgeon's instructions, get the tests HE prescribes and do what he instructs to do; normally repeated punctures with a fine needle (almost painless) to extract the liquid with syringe do suffice.

It is likely a serum cavity. You would need a sonogram or  MRI to define this. Best of luck . You might need further surgery to eradicate it, if it is a serum cavity.

Dear Martin51 diagnosis of the seroma is very easy with ultrasound examination. Treatment of the persistent seroma is surgical excision including the capsule. Good luck.