Hydronephrosis is distention and dilation of the renal pelvis, usually caused by obstruction of the free flow of urine from the kidney.

Signs and symptoms

The signs and symptoms of hydronephrosis depends upon whether the obstruction is acute or chronic. Unilateral hydronephrosis may even occur without symptoms!

Blood tests can show elevated creatinine and electrolyte imbalance. Urinalysis may show an elevated pH due to the secondary destruction of nephrons within the affected kidney.

Symptoms that occur regardless of where the obstruction lies include loin or flank pain. An enlarged kidney may be palpable on examination.

Where to obstruction occurs in the lower urinary tract, suprapubic tenderness (with or without a history of bladder outflow obstruction) along with a palpable bladder are strongly suggestive of acute urinary retention, which left untreated is highly likely to cause hydronephrosis.

Upper urinary tract obstruction is characterised by pain in the flank, often radiating to either the abdomen or the groin. Where the obstruction is chronic renal failure may also be present. If the obstruction is complete, an enlarged kidney is often palpable on examination.

Aetiology

The obstruction may be either partial or complete and can occur anywhere from the urethral meatus to the calyces of the renal pelvis.

The obstruction may arise from either inside or outside the urinary tract. Intrinsic obstructions (those that occur within the tract) include blood clots, stones, along with tumours of the kidney, ureter and bladder. Extrinsic obstructions (those that are caused by factors outside of the urinary tract) include pelvic tumours, strictures of the ureters, and neurological defecits .

Complications

Left untreated bilateral obstruction (obstruction occuring to both Kidneys rather than one) has a poor prognosis.

Treatment

Treatment of hydronephrosis focusses upon the removal of the obstruction and drainage of the urine that has accumulated behind the obstruction. Therefore, the specific tretment depends upon where the obstruction lies, and whether it is acute or chronic.

Acute obstruction of the upper urinary tract is usually treated by the insertion of a nephrostomy tube. Chronic upper urinary tract obstruction is treated by the insertion of a ureteric stent or a pyeloplasty .

Lower urinary tract obstruction (such as that caused by bladder outflox obstruction secondary to prostatic hypertrophy) is usually treated by insertion of a urinary catheter or a suprapubic catheter .

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