Renal Biopsy

ByTamer ElSaid, MD

Associate Professor of Internal medicine and Nephrology Faculty of Medicine – Ain Shams University

Background

A renal biopsy is a procedure 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.

Renal biopsy is used to diagnose renal diseases ranging from infection to transient rejection to renal cell carcinoma.

Once a biopsy diagnosis is established, it can be used to help guide treatment options and may also assist in determining prognosis of the underlying condition.

IndicationsRenal biopsy is typically performed under ultrasonographic or rarely CT guidance.

Most common indications:

Unexplained acute or rapidly progressive renal failureAcute nephritic syndromeNephrotic syndromeIsolated nonnephrotic proteinuriaIsolated glomerular hematuriaRenal masses (primary or secondary)Renal allograft dysfunction Renal transplant rejectionSystemic diseases with renal involvement eg connective-tissue diseases such as SLE

‘All these indications are not absolute. In each situation, if associated clinical and laboratory investigation suggest a predictable histological pattern, kidney biopsy may not be required.’

ContraindicationsAbsolute:Abnormal coagulopathyUncontrolled hypertensionActive renal or perirenal infectionSkin infection at biopsy site

Relative:Uncooperative patient or unable to lie flat on bedAnatomic abnormalities of the kidney which may increase riskSmall kidneys*Solitary kidney

Equipment

Anesthesia

Renal biopsy is performed under local anesthesia using 1% lidocaine.Positioning

The patient is placed in the prone position, usually with a towel or pillow placed underneath the abdomen to ensure appropriate positioning.

Ultrasound guidance

Post-procedural care

After the physician has finished obtaining all the tissue for the biopsy, the needle is removed and pressure is applied to the biopsy site to tamponade any potential bleeding, and, finally, a bandage is applied.

The patient should typically lay supine in bed for 6-8 hours immediately after the procedure.

In total the patient should expect to stay in the hospital for at least 12 hours and may have to spend one night in the hospital after the procedure.

During this time, the patient will be given proper pain medication, urine will be checked for blood, and blood counts and vital signs will be monitored throughout the patient’s stay in the hospital.

ComplicationsThe most common complication of renal biopsy is pain and bleeding at the biopsy site.

Bleeding may occur in 3 distinct locations within the kidney: into the collecting system, under the renal capsule, or into the perinephric space.

Another known complication of a renal biopsy is the development of an arteriovenous fistula. (incidence: up to 18% - In most cases, asymptomatic, but some patients may experience symptoms such as hematuria, hypertension, and/or renal insufficiency.

Treatment consists of selective angioembolization performed by a vascular interventional radiologist to halt the bleeding.

The image depicts perinephric hematoma after renal biopsy.

Adequacy of tissue sampling

Sample size – two cylinders with a minimal length of 1 cm and a diameter of at least 1.2 mm are needed.

Needle gauge: 16 - 18 gauge (G).

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The Renal Biopsy Laboratory handling

Biopsy adequacy:– Cortex and medulla– 1-2 glomeruli EM– 3-5 glomeruli IF– 6 glomeruli PS (native kidney)– 10 glomeruli PS (renal allograft)

Sectioning and fixation

Diagram to illustrate division of kidney biopsy cores in the absence of a dissecting microscope for laboratories using immunofluorescence

The standard approach is to first procure tissue for electron microscopy (EM) from each core by removing 1 mm cubes from the ends and placing them in cooled glutaraldehyde or other fixative suitable for EM [Figure 4]. Some clinicians prefer that the pathology laboratory obtain tissue for EM from the ends of the formalin-fixed tissue. If the specimen is to be sent to a laboratory that uses immunofluorescence (IF), the first core can be cut in half by cross-sectioning and the larger piece placed in formalin or another fixative suitable for light microscopy (LM); the smaller portion is saved for IF evaluation. If a second core is obtained, the ends should be taken for EM and the specimen again divided almost in half, with the larger tissue core now kept for IF and the smaller for LM.

Biopsy Laboratory handling

1- fixation (Immediate):• 10 % NB Formalin (paraffin sections)• 4% Gluteraldehyde (EM)• No fixation (Immunofluorescence)

2- Paraffin sections cut at 3 u thickness

3- Stains: HE PAS GMS TC CR …..HE PAS GMS HE TC HE PAS GMS HETC HE HE PAS GMS HE TC PAS

GMSHE TC (CR, Microbial stains, others.)

4- Immunohistochemistry (IG, C, other antigens)

5- Immunofluorescence (IG, C)

Biopsy Fixation

10% Neutral Buffered Formalin Solution:Why?1. Cheap2. Commonly available3. Suitable for:– All histological stains– Immunohistological methods (not IF)

4. Reversible: Possible to transfer to another fixative for electron microscopy.

The Renal Biopsy Laboratory handling

• HE• PAS• JNS• TC• HE• PAS• JNS• TC

3-4 microns24 Sections

Extra sectons for CR, Microbial stains, IHC etc.

Morphological examination:1. Glomeruli2. Tubules3. Interstitium4. Blood vessels

Renal Biopsy Morphological Examination

Primary Site of Renal PathologyGlomerulus

• Glomerular pathology: – Inflammation– GBM changes– Scarring– Abnormal deposits– Cellularity

Tubules • Tubular pathology :

– Cellular injury– Regeneration – Atrophy – Casts

Interstitium • Interstitial

pathology:– Cellular infiltrates– Edema/fibrosis

Vascular disease • Vascular pathology:

– Inflammation– Sclerosis– Hyalinosis– Thrombosis

? Stain

Activity of disease:• Cellular proliferation• Crescent formation• Necrotizing lesions• Inflammation

Chronicity of disease :• Tubular atrophy• Fibrosis• Vascular sclerosis

Renal pathology report Disease Stage

The Renal Biopsy Stains1. HE General

2. PAS Basement M. & Mesangial matrix

3. Trichrome Fibrosis

4. Silver Basement M. & Mesangial matrix

5. Congo red Amyloid

6. MSB Fibrin

Structure/Component PAS Jones Masson’s trichrome

Basement membrane Red Black Deep blue

Mesangial matrix Red Black Deep blue

Interstitial collagen Negative Negative Pale blue

Cell cytoplasm (normal) Negative (most) Negative Rust/orange

Immune complex Negative Negative Bright red

Amyloid Negative Negative Light blue

Tubular casts Red Gray to black Light blue

Staining characteristics of selected normal and abnormal renal structures

SATINING OF RENAL TISSUE COMPONENTS

FEATURE HE PAS TRICHROME JONES/GMS

Cellularity Excellent Excellent Poor Poor

Mesangial M Poor Excellent Variable Excellent

Glom. Sclerosis Poor Excellent Excellent Good

Immune Cox. Poor Poor Variable Negative

Basement M. Poor Excellent Good Excellent

Fibrosis Poor Poor Excellent Excellent

Vascular hyaline Good Poor Good Negative

Thrombi Good Poor Good Variable

Thank You

Reference Agarwal SK, Sethi S, Dinda AK. Basics of kidney biopsy: A nephrologist’s perspective. Indian Journal of Nephrology. 2013;23(4):243-252. doi:10.4103/0971-4065.114462.