Symptoms of hydronephrosis include pain sensation in the lower back, difficulty in urination, nausea and vomiting, hematuria and fever. The clinical manifestations of hydronephrosis are not quite the same according to the site of urinary tract obstruction, primary etiology, degree, and duration, and can be divided into upper urinary tract obstruction and lower urinary tract obstruction. Some patients with hydronephrosis are asymptomatic, while others present with severe clinical manifestations such as pain sensation in the lower back and abdomen, difficulty in urination, nausea and vomiting. Upper urinary tract obstruction refers to the obstruction above the ureteral orifice, the symptoms of hydronephrosis appear earlier, and there may even be renal colic, nausea, vomiting, hematuria, renal area percussion pain and other manifestations, and fever symptoms may appear when combined with infection. Lower urinary tract obstruction refers to the obstruction of the bladder, urethra and other parts of the bladder, hydronephrosis appears later, mainly manifested as difficulty in urination, bladder emptying obstruction or even urinary retention. Patients with hydronephrosis should go to regular hospitals in time, complete relevant examinations such as renal ultrasound, renal venography and other examinations as prescribed by the doctor, identify the causes of hydronephrosis, and follow the doctor’s instructions for treatment.