Renal Biopsy

A targeted, image-guided sampling of a kidney lesion - used in selected patients to confirm the diagnosis before deciding whether treatment, surveillance or simply reassurance is appropriate.

What is a renal biopsy?

A renal biopsy uses a fine needle, guided by ultrasound or CT, to take one or two small samples from a kidney lesion. The samples are examined under the microscope to determine whether the lesion is benign, malignant, and (if malignant) what type. The information often changes the treatment recommendation - particularly for small, incidentally discovered kidney masses.

Who is it for?

Biopsy is usually considered when:

  • A small kidney lesion is detected and surveillance is being weighed up against surgery.
  • Imaging is uncertain about whether a lesion is cancer or benign (for example, oncocytoma or angiomyolipoma).
  • Patients have a single kidney, reduced kidney function, or other conditions that make major surgery higher risk - so avoiding unnecessary surgery is especially valuable.
  • Multiple kidney lesions or a history of another cancer raises the possibility of secondary spread rather than primary kidney cancer.
  • Patients are considering focal (ablative) therapy, where knowing the tissue diagnosis is important.

Not every kidney lesion needs a biopsy - many tumours can be diagnosed with enough confidence on imaging alone. Dr Kooner will discuss whether biopsy changes management in your specific case.

Key points

  • Usually performed as a day procedure under local anaesthetic and sedation.
  • Guided by ultrasound or CT for precise needle placement.
  • Takes 20–40 minutes in total.
  • Results typically take 1–2 weeks, after which Dr Kooner will talk them through.

How it is performed

  1. You lie on your front or side on an imaging table.
  2. The skin over the kidney is cleaned and numbed with local anaesthetic.
  3. A fine biopsy needle is passed through the skin into the lesion under image guidance.
  4. Usually one to three tiny samples are taken.
  5. The needle is removed and a small dressing applied.
  6. You rest in recovery for several hours so the kidney can be monitored.

Risks & considerations

  • Bleeding - small bruising inside the kidney is common and usually settles without treatment. Significant bleeding is uncommon.
  • Blood in the urine for a day or two.
  • Pain at the biopsy site - usually mild, controlled with simple pain relief.
  • Infection - uncommon.
  • "Non-diagnostic" sample - occasionally the sample does not show enough tissue to give a definite answer, and a repeat biopsy or direct surgery is then discussed.
  • Tumour seeding along the needle tract - extremely rare with modern technique.

Frequently asked questions

Does a biopsy mean I definitely have cancer?

No. A biopsy is used precisely because it is not yet clear - a benign result is a common and welcome outcome.

Why not just remove the tumour straight away?

For small lesions, surgery carries its own risks and removes normal kidney tissue. If biopsy shows a benign lesion or an indolent cancer, surveillance may be the better choice for some patients. The decision is individual.

Will I be awake?

Usually yes, with local anaesthetic at the biopsy site and light sedation for comfort. Some patients prefer a short general anaesthetic and that can be arranged.

Can I go home the same day?

Usually yes, after a few hours of monitoring. You will need someone to drive you home and stay with you overnight.

Related services

Kidney CancerOverview of diagnosis and treatment. Renal CystsWhen a cyst needs more than imaging. Partial NephrectomyKidney-preserving tumour surgery.

Renal Mass Patient Information Brochures

Partial removal of the kidney (robotic) PDF Cryoablation (freezing) of a renal tumour PDF Radiofrequency ablation (heating) of a renal tumour PDF

Speak with Dr Kooner's rooms

Arrange a consultation or request a second opinion on kidney cancer, stones, or reconstructive kidney surgery.

02 8382 6980 Contact the Clinic