Clinical meaning
Obstructive uropathy refers to any structural or functional obstruction of urine flow at any level of the urinary tract, from the renal pelvis to the urethral meatus. When urine outflow is blocked, hydrostatic pressure builds retrograde through the urinary system, leading to progressive dilation of the structures proximal to the obstruction. Hydronephrosis is the dilation of the renal pelvis and calyces resulting from urine accumulation when drainage is impaired. The rising intraluminal pressure is transmitted to the renal parenchyma, compressing the renal tubules and peritubular capillaries. This compression reduces glomerular filtration rate and impairs tubular function, including the ability to concentrate urine, reabsorb sodium, and secrete hydrogen and potassium ions. If the obstruction is unrelieved, progressive ischemia and inflammation lead to tubular atrophy, interstitial fibrosis, and irreversible nephron loss. The kidney can sustain significant damage within 24 to 48 hours of complete obstruction. Obstruction may be classified by location (upper tract involving ureter or renal pelvis, or lower tract involving bladder or urethra), by onset (acute or chronic), and by degree (partial or complete). Upper tract obstruction is most commonly...