In hydronephrosis from pelvi-ureteric junction (PUJ) obstruction (idiopathic or congenital hydronephrosis), which of the following statements are false?
The condition may be asymptomatic It can be diagnosed in utero Ultrasound scanning is the least invasive method of imaging If there is more than 5 per cent of function in the obstructed kidney, a procedure to preserve the kidney is carried out