What it is (overview)

A kidney biopsy with imaging guidance is a diagnostic procedure in which a specialist (often a nephrologist or interventional radiologist) removes a very small tissue sample from your kidney using a thin needle. The needle is placed with help from real-time imaging guidance—most commonly ultrasound, and sometimes a CT scan—to improve accuracy and reduce the risk of complications. This is why it is sometimes called an image-guided renal biopsy.

The tissue sample is examined under a microscope by a pathologist. The analysis looks at the kidney’s filtering units (glomeruli), tubules, blood vessels, and supporting tissue to identify signs of:

Inflammation, scarring, immune-related injury, infection, medication-related damage, or abnormal growth (such as a tumor). A biopsy does not measure kidney function the same way blood tests do (like creatinine or eGFR). Instead, it helps explain why kidney function is changing or why urine findings (protein or blood) are present.

What results can mean (in plain language): Your report may describe a specific diagnosis (for example, IgA nephropathy) or patterns of injury (such as “active inflammation” versus “chronic scarring”). In general, findings suggesting active inflammation may indicate a condition that could improve with the right treatment, while findings showing more long-term scarring may suggest permanent damage where the goal is to slow progression and protect remaining kidney function. Imaging guidance itself doesn’t change the diagnosis—it helps the clinician safely collect the best-quality sample for accurate interpretation.

When & why it's usually done

Doctors typically order a kidney biopsy when blood and urine tests, symptoms, and imaging are not enough to clearly diagnose the cause of kidney problems or to guide treatment. It is most often recommended when the results will directly affect medical decisions—such as whether to start immune-suppressing medicines, adjust existing therapies, or clarify prognosis.

Common reasons a kidney biopsy with ultrasound or CT guidance may be done include:

Unexplained decline in kidney function (rising creatinine, falling eGFR) especially when the cause is uncertain.

Significant protein in the urine (proteinuria), including suspected nephrotic syndrome (often associated with swelling of the legs or around the eyes).

Blood in the urine (hematuria), especially when persistent or accompanied by proteinuria or reduced renal health.

Suspected glomerular disease (damage to the kidney’s filters), which often requires biopsy for a precise diagnosis and treatment plan.

Possible medication- or toxin-related kidney injury, when identifying the pattern of damage may change management.

Systemic autoimmune disease affecting the kidneys, such as lupus, when determining severity and type of involvement guides therapy.

Evaluation of a kidney mass in selected situations, when imaging alone cannot determine whether a lesion is benign or malignant (your team will decide if biopsy is appropriate based on location and risk).

Kidney transplant evaluation (if applicable), to assess rejection, drug toxicity, or recurrent kidney disease.

Imaging guidance is used to precisely target the kidney tissue and avoid nearby structures. Ultrasound guidance is common because it provides real-time visualization without radiation, while CT-guided biopsy may be chosen when anatomy is difficult to see on ultrasound.

Common diseases related to it

• IgA nephropathy
• Lupus nephritis (kidney involvement from systemic lupus erythematosus)
• Membranous nephropathy
• Minimal change disease
• Focal segmental glomerulosclerosis (FSGS)
• Rapidly progressive glomerulonephritis (including ANCA-associated vasculitis)
• Interstitial nephritis (often medication-related)
• Diabetic kidney disease (when findings are atypical or diagnosis is uncertain)
• Hypertensive nephrosclerosis (when evaluation is unclear)
• Amyloidosis affecting the kidneys
• Kidney infection-related inflammatory disease (selected cases)
• Kidney tumors or indeterminate renal masses (selected cases)

Health goals where it may help

• Clarifying the cause of abnormal kidney tests to protect long-term renal health
• Guiding targeted treatment to preserve kidney function and slow chronic kidney disease progression
• Determining whether kidney injury is reversible (active inflammation) versus more chronic scarring
• Supporting medication decisions in nephrology care (for example, whether immune-suppressing therapy is appropriate)
• Monitoring and managing complications of systemic autoimmune disease that can affect the kidneys
• Evaluating unexplained proteinuria or hematuria to reduce future risk of kidney failure
• Helping plan follow-up testing and personalized care based on biopsy-proven diagnosis