From the photograph and the history it appears to be incisional hernia to me
However if the sonography report says that there is a fluid collection underneath the skin. It is better to get it aspirated under ultrasound guidance and send the fluid for culture and sensitivity
If the swelling turns out to be hernia then we might need to fix a mesh during its repair. In that case any previous collection might infect the mesh and it would be difficult to clear the infection then
Next Steps
ultrasound guided aspiration of the fluid and culture sensitivity
Health Tips
consult a general surgeon for physical examination