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