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A14. Genitourinary tract biopsy: Indications and technique

Techniques of biopsy

  • Bleeding parameters should be evaluated before
  • Percutaneous biopsies are usually guided by US with local anaesthesia
  • Urothelial lesions
    • Biopsied with cystoscopy or through percutaneous catheters
  • Other lesions
    • Renal masses
    • Retroperitoneal masses
    • Retroperitoneal lymph nodes
    • Biopsied percutaneously or by open surgery

Kidney biopsy

  • Kidney biopsy is not performed for urological diseases but for nephrological diseases
  • Indications
    • Glomerulonephritis
    • Renal transplant evaluation
    • Renal mass where non-invasive imaging is inconclusive
      • Renal masses can be diagnosed with high specificity by non-invasive imaging in most cases
  • Technique
    • Can be acquired percutaneously or by open surgery
  • Complications
    • Bleeding
    • Tumour seeding is rare

Bladder biopsy

Cystoscopy, also called cysturethroscopy, is a procedure where a cystoscope (an endoscope) is inserted into the urethra to examine the urethra, urethral sphincter, prostate, urinary bladder, and uretral orifices. Fluid is continously irrigated into the bladder to prevent it from collapsing and reducing view. The endoscope can visualise the organs, take biopsy samples, and perform a limited number of therapeutic interventions like cauterisation. It's one of the most common procedures performed in urology.

Technique

  • Disinfection of urethral area
  • Application of lidocaine gel
  • Prepare conductive or non-conductive irrigation fluid
  • Insert the cystourethroscope
  • Inspect all parts of the urethra, bladder, and ureteral orifices

Enhanced imaging

Not all bladder tumours are easily visible with the naked eye using a cystoscope (called white light cystoscopy), especially carcinomas in situ. Two techniques allow for improved detection of bladder cancer.

Photodynamic diagnosis (PDD), also called fluorescent cystoscopy, is often used, where a fluorescent dye (photosensitiser) called hexyl aminolevulinate (HAL, Hexvix®) is administered into the bladder before the procedure. Cancer cells absorb this dye and glow red or pink when special fluorescent light is shone from the cystoscope, making them easier to see.

Narrow band imaging (NBI) is a similar technique which uses a specific wavelength of light with makes blood vessels more visible. As tumours often are hypervascularised, this can help detect tumours. No photosensitiser is required.

Bladder biopsy

Bladder biopsy is frequently performed in the evaluation of suspected urinary tract malignancy, especially bladder cancer. A urine cytology must be performed beforehand, to look for malignant cells.

If no tumours are visible with "normal" white light cystoscopy but the cytology is positive, one may use photodynamic diagnosis or narrow band imaging to try to detect the tumour. One can also perform a "mapping biopsy", where biopsies are taken blindly from high predilection areas.

A standard technique for tumour biopsy (if the entire tumour cannot be resected) is the method of Bressel:

  • 1 sample from tumour
  • 1 sample from muscular layer of bladder
    • To look for muscle invasion – important for further treatment
  • 4 samples of the sides of the tumor
    • To determine the border of the tumor

Transurethral resection

An instrument called a resectoscope is similar to a cystoscope and can be used to perform transurethral resection of the bladder (TUR-B) or prostate (TUR-P). This is done under spinal or general anaesthesia. The resectoscope has a camera like a cystoscope but is thicker, and has a metallic loop on the end. The metallic loop is a monopolar cautery, which is used to resect the bladder, or the prostate from the inside of the urethra. During TUR one obtains histological samples for pathological examination.

TUR-B is indicated for as a procedure which is both diagnostic and therapeutic for all stages of bladder cancer. TUR-P is indicated for severe benign prostatic hyperplasia instead of prostatectomy. It is not used for prostate cancer.

During TUR-P, the prostate capsule is not removed. The remaining cavity will be epithelialized after a few months.

TUR syndrome

During cystoscopy the bladder is continously irrigated with fluids. During cauterization bleeding and thermal burns occur, which is washed out with fluid. In some cases, a monopolar resectoscope is used because it is cheaper than a bipolar one. To prevent burns, the fluid used to irrigate must be non-conductive, usually distilled ion-free water or glycine-based solutions. Some of this water can be absorbed, causing hypotonicity and potentiallly haemolysis. Absorbed glycine can also cause CNS problem. This usually only occurs after prolonged irrigation, and so TUR is usually kept shorter than 1 hour to reduce the risk.

Nowadays one can use bipolar resectoscope with physiological saline solution (which is also conductive and is isotonic) to prevent TUR syndrome, but this fluid is more expensive. One can also use bipolar cautery, as this eliminates the need for non-conductive fluids.


Prostate biopsy

Prostate biopsy is indicated when PSA testing or digital rectal examination gives suspicion of prostate cancer. MRi is usually indicated before biopsy, as it may make the biopsy more targeted toward the lesion.

The biopsy can be performed transrectally, transperineally, or (rarely) transurethrally. The standard is transrectal biopsy with ultrasound guidance (TRUS biopsy).

MRi-targeted biopsy is preferred, but if unavailable, a systemic approach should be used. 10-12 biopsies should be taken. Samples should be taken from each side of the prostate, more samples should be taken from the lateral aspects than the medial, and the apex should be biopsied. This is according to McNeals view of prostate anatomy.

Antibiotic prophylaxis is recommended for transrectal biopsy in all cases but not for transperineal biopsy unless the patient is immunocompromised.

Testicular biopsy

Testicular biopsy is used in the evaluation of infertility. It is not used in evaluation of testicular cancer as it increases the risk of spreading; the whole testicle is usually removed instead.