Renal biopsy

Renal biopsy
PAS stain.
ICD-9-CM	55.23-55.24
MedlinePlus	003907

Renal biopsy (also kidney biopsy) is a medical procedure in which a small piece of kidney is removed from the body for examination, usually under a microscope.^[1] Microscopic examination of the tissue can provide information needed to diagnose, monitor or treat problems of the kidney.

A renal biopsy can be targeted to a particular

]

A native renal biopsy is one in which the patient's own kidneys are biopsied. In a transplant renal biopsy, the kidney of another person that has been

transplanted

into the patient is biopsied. Transplant kidney biopsy can be performed when nothing is apparently wrong with the transplant kidney for the purposes of surveillance for hidden disease (protocol transplant biopsy). This is typically done at 0, 3 and 12 months post-transplant according to a transplant unit protocol. Biopsy of the transplanted kidney taken during the transplant operation is termed implantation transplant biopsy or post-perfusion transplant biopsy depending on the timing of the biopsy with respect to key stages of the operation. When the transplanted kidney is not working properly, biopsy may be undertaken to identify the cause of dysfunction. This is referred to as an indication transplant biopsy, because something has prompted the performance of the biopsy.

Renal biopsy may be performed with the aid of "real-time" medical imaging to guide the positioning of biopsy equipment (imaging-guided renal biopsy). Alternatively, a biopsy may be performed without imaging-guidance using indirect assessments of position such as "needle-swing" to confirm appropriate placement of biopsy equipment (blind renal biopsy).

History

Before 1951, the only way of obtaining kidney tissue from a live person was through an open operation.^[citation needed]

In 1951, Danish physicians Poul Iversen and Claus Brun described a method involving needle biopsy which has become the new standard.^[2]

Recent widespread availability of real-time imaging guidance using

having improved perceived safety of the procedure.

Indications

Kidney biopsy is performed on selected patients with

]

The following are examples of the most common reasons for native kidney biopsy:

• Haematuria (or blood in the urine) can occur with a number of conditions that affect the kidneys and urinary tract. While renal biopsy is not indicated in all cases of haematuria, it may be performed in those with glomerular haematuria (blood that is thought to come from damage to the glomerulus) or when combined with features of progressive renal disease (e.g. increasing proteinuria, elevated blood pressure and kidney failure). One example is the nephritic syndrome
  .
• Proteinuria (or protein in the urine) occurs in many renal conditions. Renal biopsy is usually reserved for patients with high or increasing levels of proteinuria, or for patients who have proteinuria along with other signs of renal dysfunction. One example is the nephrotic syndrome.
• acute kidney failure) or progress over a period of time (chronic kidney disease
  ). The cause of acute kidney failure can usually be determined without kidney biopsy. Biopsy is performed in those instances where the cause is uncertain.
• Targeted kidney biopsy can be used to obtain tissue from a
  tumour
  arising from or adjacent the kidney.

Transplant kidney biopsy is performed in the following circumstances:

• For surveillance of hidden disease involving the transplant kidney, so-called protocol renal biopsy undertaken at fixed intervals post-transplantation.
• When the transplant kidney is not working as well as expected, or when there is a deterioration in function. In these instances, biopsy is performed to exclude
  BK nephropathy, drug-toxicity or recurrence of the disease that caused kidney failure
  in the first place.

Contraindications

The safety of renal biopsy is affected by the following conditions:[3]^[4]

Absolute

• bleeding diathesis
• uncontrolled severe high blood pressure
• uncooperative patient
• presence of a solitary native kidney

Relative

• uraemia
• certain anatomical abnormalities of the kidney
• skin infection at the biopsy site
• medications that interfere with clotting (e.g. warfarin or heparin)
• pregnancy
• urinary tract infection
• obesity

Procedure

Before biopsy

Like most invasive medical procedures, a renal biopsy is not without risk (see Complications). A

]

Blood testing may be done before the biopsy to ensure that there is no evidence of infection or a

and small, shrunken kidneys.

To decrease the risk of bleeding, patients are usually advised to avoid medicines that impair clotting for one to two weeks before the biopsy. These medications include

). Strict control of blood pressure is also sought to reduce bleeding risk.

Prior to the procedure, informed consent is usually taken. Arrangements will also be made to ensure that appropriate post-biopsy care and supervision is in place. Fasting is usually not required. However, this will depend on centre preference.

During biopsy

Renal biopsy is typically performed by a

]

In the case of a native kidney biopsy, the procedure will be performed with the patient lying on their stomach (

]

The site of biopsy is prepared antiseptic solution and sterile drapes are applied. If real-time imaging is used, sterile coverings will be placed on the equipment. The person performing the procedure (proceduralist) will wash their hands and don a sterile gown and gloves. A mask may or may not be worn.

The biopsy is usually performed while the patient is awake or with mild sedation. Use of a general anaesthetic is typically not required.

After the site is prepared, the proceduralist injects

into the skin, through the subcutaneous tissue and down to and around the kidney. There may be a sharp sting as the local anaesthetic is injected. After a few seconds, the site will be numb and only a sensation of pressure should be felt. A small 1–2 mm incision is made to allow insertion of the biopsy needle. In most cases, real-time imaging will be used to guide positioning of the local anaesthetic and biopsy needles. In the case of blind biopsy, this will not be used. A loud click may be heard as the spring-loaded biopsy needle is fired into the kidney to obtain a tissue sample. The resulting core of kidney tissue is usually less than 1 mm in diameter and up to 1 cm long. This may be done more than once to obtain sufficient kidney tissue.

A

.

When enough kidney tissue has been obtained, pressure will be applied to the biopsy site. After a period of time, it will be cleaned and dressed. Sutures are usually not required.

After biopsy

Post-biopsy care will differ from centre to centre. Most hospitals will observe patients who have had renal biopsy for 4–6 hours to minimise the risk of bleeding. Blood pressure and urine are frequently monitored to ensure the patient does not have any bleeding complications. Mild-moderate pain is managed with simple

acetaminophen

. Severe pain is usually an indication of bleeding complication, and may prompt a longer hospital stay and further tests.

If there are no observed complications during this period, most hospitals will discharge patients and allow them to return home. Other centres will admit patients who have had renal biopsy overnight for observation.

Most hospitals will discharge patients post-renal biopsy with written instructions on what to do if complications occur.

Complications

Serious complications of renal biopsy are uncommon. The risk of complications will vary from centre to centre based on experience and other technical factors.

The most common complication of kidney biopsy is bleeding. This reflects the density of blood vessels within the kidney and observation that individuals with

) or open surgery. In most cases, bleeding can be controlled and the kidneys are not lost. Rarely, a heavily damaged kidney may need to be removed.

Infection is rare with modern sterile operating procedures. Damage to surrounding structures, such as bowel and bladder (more likely with transplant kidney biopsy), can occur.

Occasionally, a biopsy will have to be abandoned prematurely due to technical issues such as inaccessible or small kidneys, obscured kidneys, difficult to penetrate kidneys or observation of bleeding complication. Further, after the biopsy has been completed, microscopic examination of the tissue may reveal heavily scarred tissue prompting recommendation for re-biopsy to avoid sampling error.

As with all treatments, there is a risk of allergy to the disinfectant solution, sedation, local anaesthetic and materials (latex gloves, drapes, dressings) used for the procedure.

Finally, the biopsy needle may join an artery and vein in the kidney, resulting in the formation of an

.

References