Patients with hydronephrosis may not exhibit any symptoms. Whether symptoms are present depends on factors such as the extent of renal damage caused by hydronephrosis, the severity of the hydronephrosis, and the duration of hydronephrosis. Some patients might only notice the issue due to a lump in the abdomen or a swelling sensation in the lower back, prompting them to undergo ultrasound imaging that reveals hydronephrosis. Hydronephrosis can cause renal colic, and patients may also experience nausea, vomiting, and reduced urine output. When hydronephrosis is complicated by infection, symptoms like chills, shivering, fever, and headache can occur. Some patients may first present clinically with a urinary tract infection, showing symptoms like fever, frequent urination, urgent urination, and painful urination. In rare cases, hydronephrosis can rupture and lead to bleeding.