To determine the cause of kidney problems, it is sometimes necessary to undertake a kidney biopsy. This is done in the radiology department as a day procedure. Under local anaesthetic, with ultrasound guidance, two small pieces of kidney tissue are taken through a needle to allow examination under a microscope. It takes about 30 minutes but you will then need to lie quietly for at least 4 hours and then gently mobilise for a further 2 hours. At that stage you should be able to go home but you won’t be able to drive yourself. Rare complications include bruising and bleeding from the biopsy site, and sometime this requires you to stay overnight. It is important to tell your doctor if you take aspirin or warfarin.