Urinary tract infections can involve many parts of the urinary system, with upper urinary tract infections being mainly pyelonephritis and lower urinary tract infections being mainly cystitis. Patients often present with discomfort such as frequent urination, urgency, painful urination and lower abdominal pain, which may be accompanied by systemic symptoms such as fever, chills and headache. Some patients may not have any symptoms and only pathogens are found during urine tests.