It is is an unusual procedure. They are not often requested by a kidney doctor (nephrologist). They are only done when really necessary.
What is a kidney biopsy?
It’s a diagnostic test used when blood tests, urine tests, or imaging can’t fully explain a kidney problem.
The tissue sample lets a nephrologist (hospital kidney doctor) see inflammation, scarring, immune deposits, or other abnormalities at the microscopic level.
It helps doctors diagnose kidney diseases, determine how severe they are, and guide treatment.
How is a kidney biopsy done?
The most common type is a percutaneous (through the skin) biopsy.
Step-by-step
- Preparation
- Blood tests are done to ensure normal clotting.
- You blood pressure is taken. It should be controlled, preferably below 140/90.
- You may be asked to stop blood thinners (e.g. aspirin, warfarin .. at least a week before the biopsy).
- You lie on your stomach (or on your back if it’s a transplanted kidney).
- Imaging guidance
- An ultrasound (or CT scan) is used to locate the kidney precisely.
- Local anaesthesia
- The skin and deeper tissues are numbed. You’re usually awake but relaxed.
- Needle biopsy
- A special spring-loaded needle is inserted through the skin into the kidney.
- You may be asked to hold your breath briefly.
- Typically 1–3 small samples are taken (takes seconds).
- After the procedure
- You rest flat for 6+ hours.
- Urine and vital signs are monitored for bleeding.
- Most people go home the same day or after overnight observation.
Less common approaches
- Transjugular biopsy (through a neck vein) – used if bleeding risk is high.
- Surgical biopsy – rare, done if other methods aren’t possible.
Pros (Benefits)
✔ Accurate diagnosis – identifies the exact kidney disease
✔ Guides treatment – helps decide which medication to use (e.g. steroids, immunosuppressants)
✔ Prognosis – shows how much damage or scarring is present – hence allowing a prediction of what will happen in the future
✔ Avoids guesswork – prevents unnecessary or harmful treatments
Cons (Risks and Downsides)
⚠ Bleeding (most common risk)
- Common. 1 in 10 chance of minor bleeding with blood in the urine may occur after a biopsy – this usually settles quite quickly
- Unusual. 1 in 50 chance of a collection of blood around the kidney (bruise-haematoma), which can cause discomfort, but usually settles on its own
- Rare. 1 in 100 (or less) chance of heavier bleeding requiring the need for a blood transfusion, or an x-ray treatment (embolisation) to stop a bleeding blood vessel
- Very rare. 1 in 1000 or less. Severe bleeding requiring an operation including removal of the bleeding kidney, which may lead to kidney dialysis (that can be permanent), or death.
⚠ Pain or soreness at the biopsy site
⚠ Infection (rare)
⚠ Arteriovenous fistula
An abnormal connection between blood vessels (usually resolves on its own)
⚠ Not always definitive
Occasionally the sample is too small or inconclusive (about 1 in 20). May have to be repeated.
⚠ Activity restriction
No heavy lifting or strenuous activity for ~1–2 weeks
When is a kidney biopsy usually recommended?
- Unexplained protein in the urine
- Blood in the urine (after ‘surgical cause’ (e.g. cancer or stones) has been ruled out)
- Rapidly worsening kidney function (AKI or CKD, with no obvious cause)
- Suspected glomerulonephritis, lupus nephritis, or vasculitis
- Monitoring a kidney transplant
When should it be avoided?
- Uncontrolled high blood pressure
- Bleeding disorders
- Active kidney infection
- Small or scarred kidneys
