Hydronephrosis

Hydronephrosis: describes the dilatation of the renal pelvis and calyces associated with progressive atrophy of the kidney owing to obstruction of the outflow of urine.

Aetiology:

Obstruction increases susceptibility to infection and to stone formation; unrelieved obstruction almost always leads to permanent renal atrophy (hydronephrosis following). The causes of urinary tract obstruction include:

• Congenital anomalies (e.g. urethral valves, urethral strictures, meatal stenosis, bladder neck obstruction, ureteropelvic junction narrowing or obstruction, severe vesicoureteral reflux)

• Urinary calculi

• Prostatic hypertrophy or carcinoma

• Tumours

• Inflammation (prostatitis, ureteritis, urethritis, retroperitoneal fibrosis)

• Sloughed papillae or blood clots

• Normal pregnancy

• Function disorders (neurogenic bladder)

Complications:

When obstruction is sudden and complete, the reduction of GFR usually leads to only mild dilation of the pelvis and calyces but sometimes to atrophy of the renal parenchyma. When the obstruction is subtotal or intermittent, GFR is not suppressed, and progressive dilation ensues.

Unilateral (complete or partial) obstruction can maintain adequate renal function. In bilateral partial obstruction, the earliest manifestations are inability to concentrate the urine, reflected by polyuria and sometimes acquired distal tubular acidosis, salt wasting, renal calculi, tubulointerstitial nephritis, atrophy and hypertension (possible renal failure).

Category: Pathology Notes