Biopsy of the Kidneys, Bladder, and Prostate
Biopsy of the urinary tract requires a trained specialist (nephrologist, urologist, or interventional radiologist).
Indications for diagnostic biopsy include unexplained nephritic or nephrotic syndrome or acute kidney injury. Biopsy is occasionally done to assess response to treatment. Relative contraindications include bleeding diathesis and uncontrolled hypertension. Mild preoperative sedation with a benzodiazepine may be needed. Complications are rare but may include renal bleeding requiring transfusion or radiologic or surgical intervention.
Bladder biopsy is indicated to diagnose certain disorders (eg, bladder cancer, sometimes interstitial cystitis or schistosomiasis) and occasionally to assess response to treatment. Contraindications include bleeding diathesis and acute tuberculous cystitis. Preoperative antibiotics are necessary only if active urinary tract infection (UTI) is present. The biopsy instrument is inserted into the bladder through a cystoscope; rigid or flexible instruments can be used. The biopsy site is cauterized to prevent bleeding. A drainage catheter is left in place to facilitate healing and drainage of clots. Complications include excessive bleeding, UTI, and bladder perforation.
Prostate biopsy is usually done to diagnose prostate cancer. Contraindications include bleeding diathesis, acute prostatitis, and UTIs. Patient preparation includes stopping aspirin, antiplatelet drugs, and anticoagulants 1 week before biopsy; preoperative antibiotics (usually a fluoroquinolone); and an enema to clear the rectum. With the patient in a lateral position, the prostate is located by palpation or, preferably, transrectal ultrasonography in which an ultrasound probe inserted in the rectum provides images to help guide placement of the biopsy needle. The needle typically is inserted through the ultrasonography probe or may, alternatively, be inserted through the perineum. Multiple samples (10 to 12) are usually taken. When available, an MRI image can be digitally combined (fused) with the ultrasonographic image to better identify lesions that need to be biopsied.
Overlying structures (perineum or rectum) are anesthetized, a spring-loaded biopsy needle is inserted into the prostate, and usually 12 tissue cores are obtained. Complications include the following: