Urinary Tract Obstruction

Question 1

What is obstruction causing dilation of the renal pelvis and/or ureter called?

Answer 1

Hydronephrosis

Question 2

Common causes of UTO in children.

Answer 2

Most likely congenital abnormalities or urethral valves.

Question 3

Common causes of UTO in women.

Answer 3

In young women it is probably a pelvic tumour, pregnancy or stones.

Question 4

Common causes of UTO in men.

Answer 4

Young men = stones

Elderly men = prostatic disease

Question 5

Explain the pathophysiology of UTO.

Answer 5

Urine continues to form despite the obstruction.

This leads to progressive rise in intraluminal pressure, there is dilation proximal to the site of obstruction and compression and thinning of the renal parenchyma. This leads to reduced size of the kidney.

Acute obstruction is followed by transient renal arterial vasodilation succeeded by vasoconstriction.

Question 6

Causes of UTO

Answer 6

Calculus, blood clot, sloughed papilla or tumour of renal pelvis, ureter or bladder.

Pelviureteric neuromuscular dysfunction, ureteric stricture, ureterovesical stricture, congenital megaureter, congenital bladder neck obstruction, neuropathic bladder.

Pelviureteric compression, tumours, diverticulitis, aortic aneurysm, retroperitoneal fibrosis, prostatic obstruction.

Question 7

Clinical features of acute upper tract obstruction.

Answer 7

Loin pain radiating to groin. Can have sumperimposed infection +/- loin tenderness or an enlarged kidney

Question 8

Clinical features of chronic upper tract obstruction.

Answer 8

Flank pain

Renal failure

Superimposed infection

Polyuria may occur due to the impaired urinary concentration.

Question 9

Clinical features of acute lower tract obstruction.

Answer 9

Severe suprapubic pain +/- confusion (elderly).

Distended, palpable bladder containing around 600 ml

Dull percussion of bladder

Question 10

Causes of acute lower tract obstruction.

Answer 10

Prostatic obstruction

Urethral strictures

Anticholinergics

Blood clots

Alcohol

Constripation

Post-op

Infection

Neurological

Question 11

Clinical features of chronic lower tract obstruction.

Answer 11

Urinary frequency

Hesitancy

Poor stream

Terminal dribbling

Overflow incontinence

Distended palpable bladder +/- large prostate

Question 12

Causes of chronic lower tract obstruction.

Answer 12

Prostatic enlargement

Pelvic malignancy

Rectal surgery

CNS disease such as transverse myelitis

Question 13

Complications of chronic lower tract obstruction.

Answer 13

UTI

Urinary retention

Renal failure

Question 14

Investigations for UTO.

Answer 14

Bloods - U&Es, Crea, FBC, PSA

Urine - Dipstick for blood and MC&S

Ultrasound

If there is hydronephrosis or hydroureter arrange a CT scan

Radionuclide imaging to do a functional assessment

Question 15

Treatment of upper tract obstruction.

Answer 15

Nephrostomy or ureteric stent

(Stent may cause significant discomfort to patients and they should be warned before)

Alpha blockers can help reduce ureteric stent pain.

Question 16

Treatment of lower tract obstruction.

Answer 16

Insert a urethral or suprapubic catheter to relieve acute retention.

In chronic you only catheterise if there is pain, UTI, or renal impairment.

Sometimes intermittent catheterisation is done.

Monitor weight, fluid balance and U&Es closely.

Treat underlying cause

After 2-3 days TWOC.

Question 17

Problems of ureteric stenting

Answer 17

Pain

Trigonal irriation

Haematuria

Fever

Infection

Tissue inflammation

Encrustation

Biofilm formation

Question 18

Explain obstructive megaureter.

Answer 18

Childhood condition resutling from the presence of a region of defective peristalsis at the lower end of the ureter adjacent to the ureterovesical junction.

This is more common in males.

Presents with UTI, flank pain or haematuria.

Diagnosis is made on imaging with US, CT or if necessary ascending ureterography.

Question 19

Explain retroperitoneal fibrosis.

Answer 19

Inflammatory fibrotic tissue encases the aorta and ureters.

Three times more common in men than in women and is an IgG4-related disease.

Extraluminal ureteric obstruction leads to unilateral or bilateral obstruction.

Thought to be either an autoallergic response to elakage from atheromatous plaque or a systemic autoimmune disease.

Question 20

Causes of retroperitoneal fibrosis.

Answer 20

Idiopathic (60-70%)

Secondary such as drugs, malignancy, infection and surgery/radiotherapy.

Question 21

Clinical features of RPF.

Answer 21

Malaise

Low back pain

Weight loss

Testicular pain

Claudication

Haematuria

Question 22

Investigations of RPF.

Answer 22

Normochromic anaemia

CKD

Raised ESR and CRP

Increased serum IgG4 levels

USS showing poorly circumscribed peri-aortic mass

Contrast enhanced CT show mass, lymph nodes and tumour.

FDG-PET showing metabolic activity of retroperitoneal mass.

Question 23

Management of RPF.

Answer 23

Biopsy to exclude underlying infection, lymphoma or carcinoma

Ureteric stenting can be done.

Croticosteroids or rituximab.

Response to treatment done by assessing ESR, eGFR and repead FDG-PET scans.

Obstruction can be relieved surgically by ureterolysis.

Question 24

Prognostic factors of UTO.

Answer 24

Whether obstruction is partial or complete

Duration of obstruction

Presence or absence of infection

Site of obstruction