Atlas of Ultrasonography in Urology, Andrology, and Nephrology

Renal biopsy has revolutionized the study of kidney diseases. Indeed, light microscopy, immunofluorescence, and electron microscopy allow for a correct diagnosis in most cases. In daily clinical practice, the main indications for renal biopsy are the unexplained elevation of creatinine levels, hematuria, nephritic or nephrotic syndrome, and the presence of systemic diseases affecting the kidneys. Absolute contraindications are generally represented by uncontrolled bleeding diathesis, severe arterial hypertension, multiple renal cysts, acute pyelonephritis, and end-stage kidney disease with small kidneys. Classically, the patient is in the prone position, while in cases of obese or respiratory-compromised patients, the supine anterolateral position may be used. In recent decades, the technique has significantly improved with the introduction of automated biopsy needles and ultrasound, enabling real-time visualization of the biopsy needle and its path during the procedure. Bleeding complications include asymptomatic hematoma detected only during post-biopsy ultrasound checks, gross hematuria, large hematomas, and arteriovenous fistulas, which rarely may require emergent angiographic intervention or nephrectomy. However, literature data consistently agree that ultrasound-guided or ultrasound-assisted renal biopsy, in experienced hands, is a safe and successful procedure, with a low rate of serious complications. The trend among many nephrologists to replace solid biopsy with liquid biopsy should prompt reflection while emphasizing the significance of information derived from biopsy and various biomarkers. Only then can the diagnosis become more precise, allowing for personalized therapy.