*5.2.2. Perirenal collections*

In the early post transplant period, it is common to see fluid collections around the kidney in up to 50% cases. Common post-transplant fluid collections include urinome, hematoma, seroma, lymphocele, and abscess [33, 58, 62]. Rarely, they lead to a graft dysfunction or a collecting system obstruction.

US is very useful to assess the presence and size of perinephric fluid collections; however, it is not very specific for further differentiation among different types of content. The posttransplant time interval may suggest the nature of collections. Fluid collections seen in the immediate postoperative period are usually hematomas or seromas [50]. All fluid collection are identified with US and although solid echoes or septations may suggest specific diagnosis, correlation with clinical findings helps to restrict differential diagnosis, occasionally puncture with biochemical analysis of the fluid are required to final diagnosis
