Military Medical Academy
Title: Nuclear Medicine Investigation of Obstructive Uropathy
Biography: Boris Ajdinovic
Obstructive uropathy can be defined as any blockage of urine drainage from the kidney (renal calyces or renal pelvis), ureter, or bladder. As a result of the blockage, urine backs up into the kidneys, causing dilatation of the ureter, renal pelvis, and renal calyces, which can damage the kidney if it is not treated. The appearance of dilated or enlarged renal pelvis and calyces is referred to as hydronephrosis and is a sign of obstructive uropathy
There are many causes of obstructive uropathy; however, the most common causes include stones in kidneys (nephrolithiasis), ureter (ureterolithiasis) or anywhere in the urinary tract (urolithiasis). Other causes of obstructive uropathy include health conditions such as pregnancy, prostate cancer, retroperitoneal fibrosis, spinal cord injury, ureteral stricture, and congenital anomalies (e.g., ureteropelvic junction obstruction [UJO]), which is most common in children but also occurs in adults. The gold standard to assess urinary obstruction is unclear; therefore, several imaging modalities are often used. Helical CT (especially without contrast) rapidly is replacing kidneys-ureters-bladder x-rays as the first step in the radiologic evaluation of the urinary system, MRI, where available, is becoming the imaging study of choice for urinary obstruction. IV pyelography (IVP) is the procedure of choice for defining the extent and anatomy of obstruction. Invasive pyelography provides the same information as IVP without depending on renal function and can be used when the risks of IVP are considered too great. Ultrasonography is the procedure of choice for determining the presence of hydronephrosis. Other possible methods could include the Whitaker test, which is invasive and has been largely replaced by CT. Diuretic dynamic scintigraphy (renography) has been adopted as a noninvasive clinical management tool to assist in differentiation the various causes of hydronephrosis from that of obstruction.