What post-operative complication is characterized by an abdominal mass after a renal transplant?

Lymphocele is indeed characterized by the formation of an abdominal mass after a renal transplant. This complication arises due to the accumulation of lymphatic fluid typically as a result of disruption in the lymphatic drainage during the surgical procedure. The presence of a lymphocele can manifest as a palpable mass in the abdomen, and it may sometimes be associated with symptoms like pain or discomfort in the area of the transplant.

This complication is particularly relevant in the context of renal transplants because the kidney's lymphatics are often modified or disrupted during the surgical procedure, which can lead to the collection of lymph fluid. Management of a lymphocele may involve observation, ultrasound-guided aspiration, or surgical intervention if it becomes symptomatic or does not resolve spontaneously.

Other potential complications like renal artery stenosis and renal vein thrombosis do pose serious risks but generally do not lead to the development of an abdominal mass in the same way lymphoceles do. Similarly, while seromas (fluid collections that can arise after surgery) may appear similar to lymphoceles, they are typically related to serous fluid rather than lymphatic fluid. Thus, lymphocele is the most characteristic condition leading to an abdominal mass after renal transplantation.