Which pathological process is most likely occurring in a patient with unilateral nephrectomy and chronic renal insufficiency?

In a patient who has undergone unilateral nephrectomy and is experiencing chronic renal insufficiency, hydronephrosis is the most likely pathological process occurring. Following the removal of one kidney, the remaining kidney may face increased workload and potential complications due to changes in urinary flow dynamics.

Hydronephrosis refers to the accumulation of urine in the renal pelvis due to an obstruction in the urinary tract. In individuals with only one functioning kidney, if there is any obstruction in the renal outflow tract—such as from a ureteral stone, stricture, or other causes—this can quickly lead to hydronephrosis, especially as the compensatory function of the remaining kidney is taxed.

This situation is compounded by the fact that chronic renal insufficiency itself can be accompanied by various complications, some of which may contribute to or result from altered urine formation and drainage. Ultimately, the presence of hydronephrosis represents a significant risk for the single kidney remaining, as its health and function are critical for the individual.