- To detect the presence of blood (hematuria) or protein (protein urea) in the urine.
- To detect the presence of pyuria (increased number of WBCs).
- To identify crystals in the urine which may be seen in stones.
- To identify casts. Due to damage to the kidney, proteins shed tubular cells, RBCs, WBCs aggregate and get molded as they pass through the kidney and are seen as casts in the urine.
Renal biopsy involves taking pieces of the kidney tissue to observe under the microscope to check:
- Presence of protein and/or blood in the urine in stable patients.
- Unexplained acute renal failure.
- Rejection in renal transplantation.
The procedure involves placing the patient on the stomach. The kidney is located by ultrasound, local anesthetic is injected and the needle is passed until it hits the kidney cortex. Usually it does not require general anesthesia and can be done under local anesthesia.
It is contraindicated in the presence of single kidney visions where bleeding disorders or uncontrolled hypertension are present.
Complications of a renal biopsy
The most important complication after the procedure is hematuria (bleeding), this usually occurs in 5 to 10% of patients and resolves uneventually in 24 to 48 hours. Rarely is the bleeding so severe as to requiring blood transfusions.