Renal Biopsy: Indications, Contraindications, Complications and Procedure

Renal biopsy (kidney biopsy) involves the extraction of a small kidney tissue sample for microscopic examination, with the first instance of percutaneous renal biopsy credited to Alwall in 1944.

For renal conditions, the utility of renal biopsy lies in:

• Establishing a precise diagnosis
• Assessing the severity and activity of the disease
• Evaluating prognosis by gauging the extent of scarring
• Planning treatment strategies and monitoring therapeutic responses

It is important to note that renal biopsy, while providing valuable diagnostic insights, carries inherent risks of procedure-related morbidity and, in rare instances, mortality. Therefore, a comprehensive assessment of the procedure's risks and the benefits derived from histologic examination should precede each renal biopsy.

Indications for Renal Biopsy

1. Adults presenting with nephrotic syndrome (most prevalent indication)
2. Children with nephrotic syndrome unresponsive to corticosteroid treatment.
3. Acute nephritic syndrome requiring differential diagnosis
4. Instances of unexplained renal insufficiency with kidney dimensions appearing nearly normal on ultrasonography
5. Asymptomatic hematuria cases where other diagnostic tests fail to pinpoint the bleeding source
6. Individuals with isolated non-nephrotic range proteinuria (1-3 gm/24 hours) accompanied by renal impairment
7. Renal grafts displaying impaired function
8. Kidney involvement in systemic diseases such as systemic lupus erythematosus or amyloidosis

Contraindications

1. Uncontrolled severe hypertension
2. Tendency toward hemorrhagic diathesis
3. Presence of a solitary kidney
4. Renal neoplasm cases (to prevent potential spread of malignant cells along the needle track)
5. Presence of large and multiple renal cysts
6. Kidneys displaying a small, shrunken morphology
7. Active urinary tract infection, such as pyelonephritis
8. Urinary tract obstruction

Complications

1. Hemorrhage: Given the highly vascular nature of the renal cortex, a significant risk is the occurrence of bleeding, manifesting as hematuria or the formation of perinephric hematoma. Severe bleeding may occasionally require blood transfusion and, in rare cases, necessitate kidney removal.
2. Arteriovenous fistula formation
3. Infection
4. Unintentional biopsy of another organ or perforation of a viscus (such as the liver, spleen, pancreas, adrenals, intestine, or gallbladder)
5. Mortality (rare).

How is a Kidney Biopsy Done?

Kidney Biopsy Procedure

1. Obtaining the patient's informed consent is a prerequisite.
2. An ultrasound or CT scan is conducted to meticulously document the location and size of the kidneys.
3. Blood pressure should be maintained below 160/90 mm Hg. Essential hematological parameters, including bleeding time, platelet count, prothrombin time, and activated partial thromboplastin time, should register within normal ranges. Blood samples are drawn for blood grouping and cross-matching, anticipating the potential need for blood transfusion.
4. Prior to the procedure, the patient is appropriately sedated.
5. The patient assumes a prone position, and the kidney is identified with ultrasound guidance.
6. The skin over the selected site undergoes thorough disinfection, and a local anesthetic is administered.
7. A small incision is made with a scalpel to accommodate the biopsy needle. Localization of the kidney is performed using a fine-bore 21 G lumbar puncture needle, with a local anesthetic infiltrated down to the renal capsule.
8. Under ultrasound guidance, a tru-cut biopsy needle or spring-loaded biopsy gun is inserted and advanced to the lower pole. Typically, the biopsy is obtained from the lateral border of the lower pole. The patient is instructed to hold their breath in full inspiration during the biopsy. Once the biopsy is secured, and the needle is removed, normal breathing resumes.
9. The biopsy specimen is placed in a saline drop and examined under a dissecting microscope to ensure adequacy.
10. The patient is repositioned into the supine position, with continuous monitoring of vital signs and observation of urine appearance at regular intervals. Typically, patients are kept in the hospital for a 24-hour period.

The kidney biopsy process is segmented into three components for subsequent analysis: light microscopy, immunofluorescence, and electron microscopy. For light microscopy, renal biopsy specimens are routinely fixed in neutral buffered formaldehyde. Staining includes:

• Hematoxylin and eosin (for an overall assessment of kidney architecture and cellularity)
• Periodic acid-Schiff: To accentuate the basement membrane and connective tissue matrix.
• Congo red: Utilized for amyloid identification.

For electron microscopy, tissue fixation is achieved with glutaraldehyde. In immunohistochemistry, the presence of tissue deposits of IgG, IgA, IgM, C3, fibrin, and κ and λ light chains can be identified using specific antibodies. Many kidney diseases exhibit immune-complex mediation.