Hydronephrosis is a pathological condition characterized by urine accumulation in the kidney, leading to its enlargement and possible functional impairment. This article reviews key aspects of hydronephrosis, including its causes, diagnostic methods, clinical manifestations, and treatment approaches. Causes of hydronephrosis include obstructive processes, congenital anomalies, infections, and the effects of pregnancy. Diagnosis includes laboratory tests, imaging techniques, and urodynamic tests. Treatment depends on the condition's cause and severity and may consist of conservative methods and surgical intervention. Timely diagnosis and adequate treatment of hydronephrosis are important to prevent serious complications, including renal failure.