Renal Biopsy

Renal biopsy can provide a definitive histological diagnosis of glomerular or interstitial disease:

• It is particularly helpful in patients with severe proteinuria, haematuria that is not due to disease of the lower urinary tract and acute renal failure thought to be caused by intrinsic renal disease.
• The main diseases diagnosed by renal biopsy include glomerulonephritis, other glomerular disorders such as amyloid and diabetes, and interstitial nephritis.

Renal biopsy is an important investigation in the management of patients who have had a renal transplant:

• Postoperative oliguria: to differentiate acute ischaemic tubular necrosis caused by drug toxicity, acute rejection or infarction.
• Further biopsies may be required to monitor the response to anti-rejection therapy, examine for recurrence of the original renal disease, or the development of glomerulonephritis in the graft.

• Proteinuria and haematuria:
  • Isolated microscopic haematuria or proteinuria of less than 1 g/24 hours are not usually indications for renal biopsy because it is unlikely that any specific treatment would be required.
  • Microscopic haematuria with dysmorphic red cells or casts, a possible hereditary condition, associated proteinuria, hypertension or reduced glomerular filtration rate would be considered an indication for biopsy.
  • Low levels of proteinuria associated with haematuria, hypertension or reduced glomerular filtration rate would also be considered as an indication for biopsy.
  • Higher levels of proteinuria (more than 1g/24 hours), or the combination of proteinuria and haematuria (especially with casts) are indications for biopsy, because of the potential of effective treatment for glomerulonephritis and interstitial nephritis.
  • Nephrotic syndrome: in patients less than 1 year or above 10 years of age. Children between the ages of 1 and 10 years usually have minimal change nephropathy, which responds to steroid treatment and so the risks of biopsy are thought to outweigh the likely benefits of treatment. However these children may need biopsy if there is a poor response to initial treatment.
• Acute renal failure:
  • To exclude ischaemic acute tubular necrosis: with abnormal urinary sediment, proteinuria, +ve ANCA/ANA/anti-GBM antibodies, severe hypertension, no obvious cause or prolonged history.
  • Presumed ischaemic acute tubular necrosis: biopsy is indicated if recovery is delayed
• Chronic renal failure: equal-sized kidneys which are not small and shrunken, with proteinuria or dysmorphic haematuria.
• Known renal diagnosis: equal-sized kidneys which are not small and shrunken, with sudden unexplained reduction of glomerular filtration rate or unexplained increased proteinuria.

• Biopsy should be avoided in patients with obstructed kidneys, reflux nephropathy and kidneys with significant discrepancy in size and function as assessed by radionuclide studies.
• Percutaneous renal biopsy should not be undertaken in patients with polycystic kidney disease.
• Patients with renal masses, such as tumours or cysts, should only be biopsied under direct vision, by ultrasound, CT scanning or by open surgical biopsy.
• Patients with a solitary (or solitary functioning) kidney are normally considered for open surgical biopsy.
• Uncontrolled hypertension or coagulation defects, e.g. thrombocytopenia: blood pressure should be controlled and coagulation abnormalities corrected before biopsy.
• Patients with chronic renal failure and bilaterally small, shrunken kidneys should not undergo biopsy. The technique is then very difficult and the biopsy appearances are very unlikely to provide any benefit for clinical management.
• Percutaneous renal biopsy should not be performed in patients with untreated acute pyelonephritis due to the risk of developing a perinephric abscess.
• Complication rates are increased in patients with both acute and chronic renal failure.
• If both kidneys are small, as in chronic glomerulonephritis, then the risks usually outweigh the benefit.
• Uraemia prolongs the bleeding time, even when the coagulation screen is normal.
• The risk of uraemic haemorrhage can be at least partially reversed prior to biopsy by dialysis to improve platelet function, correction of the haematocrit and any underlying coagulation defect, and by giving an infusion of DDAVP (desmopressin) prior to the procedure.
• Haemorrhage is more likely to occur in patients with uncontrolled hypertension, hereditary or acquired coagulation disorders, renal amyloid, polyarteritis nodosa and those taking anticoagulants or antiplatelet agents.

• Before biopsy is performed:
  • Check full blood count, coagulation screen and bleeding time
  • Obtain written informed consent
  • Ultrasound: risk of biopsy is increased if only one kidney
• Blind biopsy of the native kidney (biopsy without imaging for localisation):
  • Should not be performed unless there are truly exceptional circumstances.
  • It is possible to visualise the kidney and biopsy under fluoroscopic control after injection of radiocontrast medium as for an IVU, but the most commonly used method for directing the biopsy is ultrasound guidance.
  • Percutaneous renal biopsy should be carried out using sedation and local anaesthesia. Children may require general anaesthesia.
  • The patient should be placed prone on top of pillows or folded sheets to compress the upper abdomen and lower ribs. Under real-time ultrasound the kidneys are visualised, the patient asked to take and hold a deep breath in inspiration.
  • To avoid the major vessels, the aim should be for the lateral border of the lower pole. Usually a 14-18 gauge, truecut type needle¹ (or automated spring-loaded biopsy gun²) is used. Under direct vision the needle tip is advanced to the renal capsule and then biopsy is taken. The use of colour Doppler greatly helps avoid the major intrarenal vessels.
• Transjugular biopsy:
  • Can be performed in patients who have an increased likelihood of bleeding complications.³
  • Technical developments have now allowed biopsy needles to be passed reliably from the renal vein into the renal cortex.
• Occasionally, open surgical biopsy is required, with the biopsy taken under direct vision and local bleeding controlled.
• Renal transplants, usually placed in one or other iliac fossa, are biopsied in the supine position. Biopsies are taken from the lateral border of the upper pole, avoiding the major vessels and ureter.
• All patients should be placed on strict bed rest for 12-24 hours after the procedure. Pulse, blood pressure, symptoms and urine colour should be closely monitored.
• Hypotension, tachycardia, abdominal/back pain, and macroscopic haematuria are indications for urgent medical review.

• Bleeding is the main complication. Post-biopsy scanning has shown that the vast majority of patients develop a perirenal haematoma, which is usually asymptomatic. Significant bleeding occurs in about 1 in 1000 cases.
• Arteriovenous fistulas may develop following biopsy. The majority disappear spontaneously with time, and treatment is only occasionally required.