A kidney biopsy can identify what is interfering with your normal kidney function. a biopsy is a diagnostic test that involves collecting small pieces of tissue, usually through a needle, for examination under a microscope. you’ll be positioned so that you are lying on your stomach. this keeps your kidneys easily accessible from your back. you may be given a pillow or towel, since you have to remain still and stay in this position for about 30 minutes. the procedure usually takes less than an hour. not everyone with kidney disease will need a kidney biopsy; you need to speak to your physician to determine if this procedure is necessary for your condition.