Hydronephrosis Flashcards
What causes it?
The common causes are prostatic obstruction (hypertrophy or tumour), gynaecological cancer and calculi.
Within the lumen: Calculus, tumour of renal pelvis or ureter, blood clot, sloughed renal papillae (diabetes, NSAIDs, sickle cell disease or trait).
Within the wall: Congenital abnormalities of the urinary tract (usually detached antenatally or in infancy). Stricture: uteric or urethral. Neuropathic bladder
How does it present when there’s an upper UT obstruction?
Results in a dull ache in the flank or loin, which may be provoked by an increase in urine volume, e.g. high fluid intake or diuretics.
Complete anuria is strongly suggestive of complete bilateral obstruction or complete obstruction of a single functioning kidney.
Partial obstruction causes polyuria as a result of tubular damage and impairment of concentrating mechanisms.
How does it present when there’s a bladder outlet obstruction?
Results in hesitancy, poor stream, terminal dribbling and a sense of incomplete emptying.
Retention with overflow is characterised by the frequent passage of small quantities of urine.
Infection commonly occurs and may precipitate acute retention of urine.
Signs on examination?
All depends on the site of obstruction. An enlarged bladder or hydronephrotic kidney may be felt on examination. Pelvic (for malignancy) and rectal (for prostate enlargement) is essential in determining the cause of obstruction
Investigations
maging: Ultrasonography is the vital investigation but helical/spiral CT scanning has a higher sensitivity for detecting calculi as well as details of the obstruction. Excretion urography identifies the site of obstruction and shows a characteristic appearance (a delayed nephrogram, which eventually become denser than the non-obstructed side).
Radionuclide studies are of no value in the investigation of acute obstruction but may help in longstanding obstruction.
Bloods to assess creatinine and function of the kidneys.
Treatment
Surgery is the usual treatment for persistent obstruction.
Elimination of the obstruction may be associated with a massive post-operative diuresis, resulting partly from a solute diuresis from salt and urine retained during obstruction and partly from the renal concentrating defect.
In some cases, definitive relief of the obstruction is not possible and urinary diversion may be required. This may simply be an indwelling urethral catheter, a stent placed across the obstructing lesion, or the formation of an ileal conduit.
