Renal Biopsy

A renal biopsy is used to obtain a segment of renal tissue, usually through a needle or another surgical instrument. Analysis of this tissue is then used in the diagnosis of an underlying renal condition.

In native kidneys, biopsy is used to identify various renal diseases, especially glomerular or interstitial pathologies. It can also aid in the diagnosis of renal masses and malignancies, the most common being renal cell carcinoma.

In a transplanted kidney, renal biopsy is indicated when graft dysfunction ensues with a rise in serum creatinine. Renal biopsy aids in diagnosing graft rejection and helps guide treatment, as well as the response to treatment in some cases.

 

Renal biopsy is typically performed by a radiologist under computed tomography (CT) or ultrasonographic guidance. However, a urologist can also perform a kidney biopsy during renal surgery.

There are multiple indications to perform renal biopsy, including the following:

• Unexplained renal failure

• Acute nephritic syndrome

• Nephrotic syndrome

• Isolated nonnephrotic proteinuria

• Isolated glomerular hematuria

• Renal masses (primary or secondary)

• Renal transplant rejection

• Renal transplant dysfunction

• Connective-tissue diseases (eg, systemic lupus erythematosus)

Paripovic et al ^[2] and Printza et al ^[3]  performed retrospective studies to determine indications for pediatric renal biopsy. Both found that nephrotic syndrome was the most common indication (32.9%). In the study by Paripovic et al, other indications included asymptomatic hematuria (23.4%), urinary abnormalities in systemic diseases (15.8%), and proteinuria (11.4%). Both studies found that glomerular disease was most prevalent.

According to Paripovic et al, the most common causes of glomerular disease were focal segmental glomerulosclerosis (20.9%), mesangioproliferative glomerulonephritis (14.6%), immunoglobulin A (IgA) nephropathy (8.9%), minimal change disease (13%), lupus nephritis (6%), and Henoch-Schönlein nephritis (4%).

Printza et al found that the most common findings included focal segmental glomerulosclerosis (15%), IgA nephropathy (13.5%), minimal change disease (10%), various stages of lupus nephritis (8.5%), Henoch-Schönlein nephritis (7.5%), membranous glomerulonephritis (7.5%), mesangioproliferative glomerulonephritis (6%), postinfectious glomerulonephritis (6%), hemolytic uremic syndrome (5%), tubulointerstitial nephropathies (3.5%), and acute tubular necrosis (2.5%).

The image below depicts a micrograph of focal segmental glomerulosclerosis.

Biopsy of renal transplant allograft 

A survey by the United Network for Organ Sharing (UNOS) showed great disparities in practice across US transplant centers regarding the timing and performance of surveillance kidney transplant biopsies for diagnosing subclinical graft rejection. The most common timeframe for surveillance biopsies was 3 and 12 months post-transplant. The 1- and 3-year graft survival was similar among centers performing biopsies compared with those not performing biopsies. The survey results showed the controversies around surveillance biopsies and the management of subclinical rejection. ^[5]

Rush et al from the Manitoba Adult Renal Transplant Program were the first to report the finding of subclinical rejection within the first 3 months after kidney transplantation. ^[6] Subclinical rejection can be broadly defined as lymphocytic infiltration of a renal allograft with normal function.

Rush et al further classified subclinical rejection as an increase in serum creatinine by more than 10% 2 weeks before the protocol biopsy and a histologic Banff score (a system used to score renal allograft histology; see Laboratory Medicine for more detail) of “ai2at2” (type 1A acute rejection) or greater. ^[7] The controversy regarding this topic is whether detecting subclinical rejection from a specific biopsy protocol can guide early successful treatment of renal allograft pathology, ultimately improving long-term graft function.

A study analyzed a 10-year follow-up of patients with subclinical rejection diagnosed at 14 days post transplantation. ^[8] The results showed a significant decrease in graft survival over the 10-year period, and the researchers concluded that subclinical rejection can predict transplant outcomes.

Another study attempted to determine the benefit of early detection of subclinical rejection and subsequent treatment with corticosteroids. ^[9] The study featured 72 patients randomized to 2 biopsy groups: one receiving biopsies at 1, 2, 3, 6, and 12 months (biopsy arm) and the other receiving biopsy at 6 and 12 months (control group). Patients in the biopsy group showed a decrease in acute rejection, reduced chronic tubulointerstitial score at 6 months, and a lower serum creatinine level at 24 months compared with patients in the control group.

On the other hand, when renal transplant dysfunction is suspected as evidenced by a rise in serum creatinine level, or clinical signs, such as fever, edema, hypertension, oliguria, and proteinuria, the allograft biopsy is mandatory for adequate histologic diagnosis. ^[10]  Some studies went on to analyze the accuracy of clinical prediction of allograft pathology related to diagnosis found after renal biopsy. ^[11] Findings revealed 43% of clinical predictions were completely correct. Of the 57% of cases in which predictions were not accurate, 26% of those cases were completely incorrect, clarifying the necessity of renal biopsy for accurate diagnosis of allograft pathology.

Renal allograft biopsy is very useful in identifying acute rejection in the transplant allograft and in guiding the treatment of antibody-mediated rejection or acute cellular rejection. Once the appropriate treatments are initiated, a repeat biopsy helps confirm adequate response to treatment.

In a high-risk transplant (ie, ABO- or human leukocyte antigen [HLA]-incompatible kidney transplants), the allograft interval biopsy schedule remains the mainstay for surveillance in this particular category of patients in whom the graft might be compromised by silent immunologic processes. ^[12]

Absolute contraindications to renal biopsy include the following:

• Uncorrectable bleeding diathesis

• Uncontrollable severe hypertension

• Active renal or perirenal infection

• Skin infection at biopsy site

The following are relative contraindications to renal biopsy:

• Uncooperative patient

• Anatomic abnormalities of the kidney that may increase risk

• Small kidneys

• Solitary kidney

The following factors may make renal biopsy difficult for the radiologist:

• Small kidneys

• Solitary kidney

• Retrorenal colon

• Highly vascularized tumors (increased risk of bleeding)

Other considerations include the possibility of infection, injection into a muscle (creating a hematoma), and the possibility of the biopsy needle inadvertently piercing other organs in close proximity to the kidney, such as the colon, spleen, and liver.

Preparation for kidney biopsy

Encourage patients to ask questions or raise any concerns they may have about the biopsy. Ask them to bring in a list of all their medications, including over-the-counter drugs, vitamins, and supplements. Let them know that they may need to temporarily stop taking medications that cause thinning of the blood, such as aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs), and anticoagulants. ^[13]

Recovery from kidney biopsy

Tell patients that after the biopsy they will generally have to lie on their back for 6-8 hours. Patients should expect to stay in the hospital for at least 12 hours and may have to spend the night in the hospital after the procedure. During the hospital stay, patients will receive pain medication, urine will be checked for blood, and blood tests and vital signs will be monitored. ^[14]

Caution patients to avoid strenuous activities, such as heavy lifting, for 2 weeks after the biopsy.

Risks of kidney biopsy

Inform patients that the most common complication is pain and bleeding at the biopsy site and that infection is rare. However, advise them to seek immediate medical attention if any of the following symptoms occur after a kidney biopsy ^[13] :

• Inability to urinate.
• Frequent or urgent need to urinate.
• Burning sensation during urination.
• Dark red or brown urine: Tell patients that it is normal to see some blood in the urine for up to 24 hours after the procedure.
• Blood or pus that saturates the bandage at the biopsy site.
• Worsening pain at the biopsy site.
• Fever.
• Faintness or dizziness.

Interpreting biopsy results

Let patients know that once you receive the complete biopsy results from the pathologist, you will review the results with them during a follow-up visit.

For helpful patient education resources, see the article What Is a Biopsy? and the slideshow What to Expect With a Biopsy.