Hydronephrosis

Hydronephrosis is dilatation of the renal collecting system.

It is a radiological sign, not a diagnosis.

Hydronephrosis may result from:

• Ureteric stone
• PUJ obstruction
• Ureteric stricture
• Retroperitoneal fibrosis
• Pregnancy
• Pelvic tumour
• Bladder outlet obstruction
• Vesicoureteric reflux
• Neurogenic bladder

Dilatation does not always mean active mechanical obstruction.

A chronically dilated collecting system can remain enlarged after the obstruction has resolved.

Presentation depends on cause.

Possible symptoms:

• Flank pain
• Renal colic
• UTI
• Haematuria
• Renal impairment
• Incidental imaging finding

Severe bilateral hydronephrosis can present with:

• Oliguria
• Hyperkalaemia
• Renal failure

Renal ultrasound: demonstrates pelvicalyceal dilatation.

Assess:

• Unilateral versus bilateral
• Cortical thickness
• Bladder distension
• Ureteric dilatation

CT defines stones and masses.

Functional renography, such as MAG3, is useful when determining whether anatomical dilatation represents true functionally significant obstruction.

The clinically important questions are:

• Is obstruction present?
• Is renal function threatened?
• Is infection present?

Do not treat the ultrasound appearance alone.

Treat the underlying cause.

Emergency decompression

Urgently decompress when hydronephrosis accompanies:

• Sepsis
• Pyonephrosis
• Acute renal failure
• Anuria
• Solitary functioning kidney obstruction
• Uncontrolled pain

Use:

• JJ stent

or

• Percutaneous nephrostomy

Chronic obstruction

Definitive treatment depends on cause:

• Stone removal
• Pyeloplasty for PUJ obstruction
• Ureteric reconstruction
• Endoscopic treatment of selected strictures
• Prostate outlet surgery
• Tumour treatment

Poorly functioning kidney

When longstanding unilateral obstruction has produced a severely damaged kidney, assess differential renal function before major reconstructive surgery.

A symptomatic nonfunctioning kidney with recurrent infection or pain may require nephrectomy if recovery is not realistic.