Which of the following is NOT a common feature of renal allograft rejection?

In the context of renal allograft rejection, understanding the typical features observed during imaging and clinical assessments is crucial.

Increased allograft size is often observed due to inflammation and edema associated with rejection. This swelling can lead to noticeable changes in the size of the transplanted kidney.

Increased cortical echogenicity is another common finding in renal allograft rejection. This occurs due to inflammatory changes and cellular infiltration, making the renal cortex appear brighter on ultrasound.

Increased prominence of renal pyramids can also occur during rejection. This is typically due to changes in the kidney's internal architecture resulting from the rejection process.

The correct answer, which is decreased flow resistance in parenchymal arteries, does not align with the expected parameters during an episode of renal allograft rejection. Typically, during rejection, one would see increased resistive indices due to vascular changes and impaired perfusion, which leads to increased flow resistance rather than a decrease. Therefore, in renal allograft rejection, decreased flow resistance is not a common feature and reflects an atypical response.