Urinary tract obstruction Flashcards
Where might obstructing lesions lie in urinary tract obstruciton?
- Lumen
- Wall of the urinary tract
- Outside the wall of the urinary tract
What are causes of urnary obstruction within the lumen of the urinary tract?
- Calculi
- Blood clot
- Cloughed papilla
- Tumour - renal pelvis, ureter, bladder
What are causes of urinary tract obstruction that originate from in the wall of the lumen?
- Ureteric/Uterovesical stricture
- Congenital bladder neck obstruction
- Urethral stricture
- Congenital urethral valve
- Neuopathic bladder
What are causes of urinary obstruction that originate from outside the ureter?
- Tumours
- Diverticulitis
- Aortic aneurysm
- Retroperitoneal fibrosis
- Accidental ligation
- Retrocaval ureter
- Prostatic obstruction
- Phimosis
What is the pathophysiology of urinary tract obstruction?
Obstruction with continuing urine formation results in:
- Progressive rise in intraluminal pressure
- Dilatation proximal to the site of obstruction
- Compression and thinning of the renal parenchyma
What are features of acute upper urinary tract obstruction?
- Loin to groin pain
- Loin tenderness
- Signs of cause - superimposed infection/enlarged kidney
What are features of chronic upper urinary tract obstruction?
- Flank pain
- Renal failure
- Superimposed infection
- Can have polyuria
What are symptoms of acute urinary retention/acute lower tract obstruction?
- Severe suprapubic pain
- Acute confusion (elderly)
What are signs of acute urinary retention?
- Distended, palpable bladder
- Dull to percussion
What residual volumes might someone have if in acute urinary retention?
400ml - 2L
What are causes of acute urinary retention?
- Prostatic obstruction
- Urethral strictures
- Anticholinergics
- Blood clots
- Alcohol
- Contipation
- Post-op
- Infection
- Neurological
What are complications of chronic urinary retention?
- Overflow incontinence
- Renal failure
- UTI
What are symptoms of chronic urinary retention?
- Urinary frequency
- Hesitancy
- Poor stream
- Terminal dribbling
- Overflow incontinence
What a signs of chronic lower tract obstruction?
- Distended, palpable bladder
- May have nelarged prostate
What are causes of chronic urinary retention?
- Prostatic enlargement
- Pelvic malignancy
- Rectal surgery
- DM
- CNS disease - transverse myelitis, MS
- Zoster - S2-S4
What investigations would you consider performing if you suspected someone had a urinary tract obstruction?
Confirm they are in retention
- Bladder scan
Investigate cause
- Bloods - U+Es, FBC, PSA
- USS KUB
- Consider X-ray/CT KUB
- Consider radionucletide studies
- Consider cystoscopy
What might you find on investgation of FBC and U+E’s in someone with a urinary tract obstruction?
- Raised urea
- Raised creatinine
- Hyperkalaemia
- Anaemia of chronic disease
What might you be looking for on USS when investigating someone with urinary tract obstruction?
Can rule out upper urinary tract dilatation. Ultrasound cannot distinguish a baggy, low-pressure unobstructed system from a tense, high-pressure obstructed one, so that false-positive scans are seen.
When would you consider radionucelotide studies?
Longstanding obstruction - to differentiate true obstructive nephropathy from retention of tracer in a baggy, low-pressure, unobstructed pelvicalyceal system.
How would you manage someone with upper urinary tract obstruction?
Consider following options
- Nephrostomy
- Ureteric stent +/- alpha blockers
- Pyeloplasty - PUJ obstruction
How would you manage acute urinary retention?
- Insert urinary catheter
- Treat cause
- Remove catheter after 2-3 days and trial output
How would you manage someone in chronic urinary retention?
- Asymptomatic - Do not catheterise
- If pain/UTI/Renal impairment - intermittent self-catheterisation
If someone was in clot retention, how would you manage them?
3-way catheter and bladder washout
What are complications that can arise with catheterisation?
- UTI
- Post-decompression haematuria
- Post-obstructive diuresis
- Renal failure
- Electrolyte abnormalities
Why does post-obstructive diuresis occur?
May occur following relief of bilateral obstruction owing to previous sodium and water overload and the osmotic effect of retained solutes combined with a defective renal tubular reabsorptive capacity (as in the diuretic phase of recovering acute tubular necrosis). This diuresis is associated with increased blood volume and high levels of atrial natriuretic peptide (ANP).
What are features of post-obstructive diuresis?
- Urine output >200ml/hr
- Postural hypotension - systolic differential >20mm Hg between lying and standing
- Weight loss
- Electrolyte abnormalities
How would you manage post-obstruction diuresis?
- Monitor weight, fluid balance + U+E’s
- Consider giving fluids
What are common problems seen in ureteric stenting?
- Stent-rlated pain
- Trigonal irriation
- Haematuria
- Fever
- Infection
- Tissue inflammation
- Encrustation
- Biofilm formation
What are causes of retroperitoneal fibrosis?
- Idipathic retroperitoneal fibrosis (RPF)
- Inflammatory aneurysms of the abdominal aorta
WHy does retroperitoneal fibrosis occur?
Fibrinoid necrosis of the vasa vasorum occurs, affecting the aorta and small and medium retroperitoneal vessels. The ureters become embedded in dense, fibrous tissue resulting in progressive bilateral ureteric obstruction
What is retroperitoneal ribrosis associated with?
- Drugs - B-blockers, bromocriptine, methyldopa
- Autoimmune disease - thyroiditis, SLE, ANCA vasculitis
- Smoking
- Asbestos
What are typical features of retroperitoneal fibrosis?
- Middle aged
- Vague loin/back/abdominal pain
- Hypertension
What investigations might you do if you suspected retroperitoneal fibrosis?
- Bloods - U+E’s, ESR, CRP, FBC
- Ultrasound - dilated ureter
- CT/MRI - Periaortic mass
- Biopsy - rule out malignancy
How would you manage someone with retroperitoneal fibrosis?
- Retrograde stent placement +/- ureterolysis
- Consider immunosuppression
