Hydronephrosis

Question 1

Define hydronephrosis.

Answer 1

Hydronephrosis refers to dilation of the renal pelvis and can be present with or without obstructive uropathy.

When kidney function is affected, this is termed obstructive nephropathy.

Question 2

How common is hydronephrosis?

Answer 2

Most commonly due to ureteral stones which are common (affect ~7% in Europe)
In older age it is more common in men due to BPH or malignancy

Question 3

What are the risk factors for obstructive uropathy?

Answer 3

• BPH
• constipation (especially in women and children)
• medication - anticholinergics, narcotics, alpha receptor agonists
• urolithiasis
• spinal cord injury, PD, MS
• malignancy

Question 4

What are the clinical features of hydronephrosis?

Answer 4

• Flank pain
• Fever
• LUTS - frequency, urgency, poor stream, incomplete emptying
• Distended abdomen/palpable bladder
• Inability to urinate
• Enlarged or hard nodular prostate on DRE
• Costovertebral angle tenderness
• Signs of organ dysfunction - tachypnoea, tachycardia, hypotension, altered GCS

Question 5

What are the complications of obstructive uropathy?

Answer 5

Causes obstructive nephropathy which can cause irreversible renal damage.

Obstruction can ultimately cause tubulointerstitial fibrosis, tubular atrophy, and interstitial inflammation.

Question 6

What are the causes of unilateral hydronephrosis?

Answer 6

Disorders in:

• Kidney
• Ureter
• Retroperitoneum
• Portions of the bladder

Question 7

What are the causes of bilateral hydronephrosis?

Answer 7

Disorders of:

• Bladder
• Prostate
• Urethra
• Pelvic malignancy
• Less commonly due to simulatenous occurrence of unilateral causes of obstruction on both sides.

Question 8

How do you diagnose hydronephrosis?

Answer 8

• Bladder scan - volume >300ml is indicative of retention.
• USS doppler kidneys - 1st procedure of choice
• CT abdo pelvis (non-contrast) - 1st line scan; detects urolithiasis.

Other:

• Bloods- if signs of sepsis, carry out sepsis 6, SOFA score
• MSU - microscopy and culture
• DRE - BPH

Question 9

What is the management of hydronephrosis?

Answer 9

Analgesia
Rehydration
Treat the underlying cause
+/- Ureteric stent OR
+/- Nephrostomy
+/- Catheter - e.g. in bilateral hydronephrosis due to BPH
+/- Suprapubic catheter
+/- Antibiotics - if signs of sepsis or urinary infection

Question 10

What are the complications of hydronephrosis and its management?

Answer 10

Urethral trauma
Ureteric stent displacement or occlusion
Post-obstructive diuresis
Severe sepsis and shock
CKD

Question 11

What is post-obstructive diuresis?

Answer 11

Seen after relief of bilateral obstruction or urinary retention.
Occurs as a response to volume expansion and accumulation of solutes in the obstructed kidneys which try to expel this once obstruction is relieved
Diuresis up to 200ml/hr may be seen
Usually resolve once homestasis resolves but may progress to a pathological form

Encourage oral hydration and avoid IV fluids if patient is able to drink.

Question 12

What is the prognosis with hydronephrosis?

Answer 12

Usually complete recovery if the obstruction is relieved promptly
BPH is a common cause of hydronephrosis but hydronephrosis is not common within BPH (2.4%)