Urinary: Obstruction Flashcards
What is the management of a patient with Haematuria?
- Stabilise the patients
- Blood
- 3 way catheter and irrigation
- CT angiogram if significant bleed
- If it doesn’t settle then intervention such as cystoscopy/interventional radiology
Which substances presents with false negatives?
-Vitamin C
What is the mechanism for acute urinary retention?
- Bladder outlet obstruction
- Low bladder contractile power
- Interrupted sensory or motor innervation of bladder and/or sphincter
What are investigations done for acute urinary retention?
- History and examination
- Bloods
- Bladder scan
- Neurological documentation important
What are the causes of acute urinary retention in men?
- BPH
- Prostate cancer
- Urethral stricture
- Prostatic infection
What are the causes of acute urinary retention in women?
- Prolapses
- Masses
- Post botox
- Fowler’s syndrome
What are the causes of acute urinary retention in both males and females?
- Clots
- Drugs
- Pain
- Major abdominopelvic surgery
- Spinal cord compression
- Spinal cord injury
- Spina bifida
- Urinary tract infections
- Constipation
- Urethral damage/rupture
- Diabetic nephropathy
- Neurological degeneration
What are management options for acute urinary retention?
- Urethral Catheterisation
- Suprapubic (if difficult)
- Preferable as long-term condition
- Risk of bowel perforation with insertion
- Should have ultrasound if laparotomy
What differentiates acute urinary retention from chronic?
It is very painful
Where can stones from in the urinary tract?
- Renal
- Ureteric (constrictions)
- Bladder (due to incomplete emptying)
- Prostatic calculi (no clinical significance )
- Urethral calculi in men (rare)
What are the effects of a ureteric obstruction?
- Therefore, a unilateral obstructive stone globally impairs renal function.
- Can also get bilateral calculi of kidney or ureters
What are features of renal and ureteric colic?
- Causes a lot of pain
- Present with renal colic
- Loin to groin pain
- Testicular pain sometimes
What are the investigations dow for renal and ureteric colics?
- History
- Examination
- Urinalysis
- CT KUB non-contrast
- Abdominal X-ray
What are the management options for renal and ureteric colics?
- Conservative management
- Non- Invasive management (Shockwave lithotripsy)
- Invasive management (Cystoscopy + lasertripsy, Percutaneous nephrolithotomy, Uteroscopy)
What are signs and symptoms of ureteric stones?
- Very painful
- Impairment in renal function
- May get stuck
What are the management options for ureteric stones?
Symptoms and stone size guide treatment
- Most stone will pass if small enough (less than 4mm)
- Pain mandates a stent and sometimes primary URS + lasertipsy
What is the pathophysiology of urosepsis?
- Blocked upper renal tract to ureteric orifice
- Standing column of septic urine in the upper urinary tract including the kidney is called pyelonephroisis
- Infection can spread to blood
What is the management for urosepsis?
- Stenting
- Nephrostomy
To drain urine
What are causes of AKI?
- Pre-renal
- Renal vein
- Renal artery
- Small vessel disease – intrinsic
- Glomerular disease - intrinsic
- Acute tubular necrosis – intrinsic
- Acute interstitial nephritis - intrinsic
- Intratubular obstruction
- Post renal obstruction
What is imaging undertaken in AKI?
- Ultrasound – perform if obstruction suspected. Not need for pre-renal/ATN
- Chest X-ray – to look for fluid overload
Why is biopsy taken if AKI suspected?
- Pre-renal and post-renal AKI ruled out
- A confident diagnosis of ATN cannot be made
- Systemic inflammatory symptoms/sign are present
What is the pathophysiology of pre-renal failure in AKI?
- Actual GFR is reduced due to decreased renal blood flow.
- No cell damage so kidney works hard to restore blood flow
- Avidly reabsorbs salt and water (ADH + Aldosterone)
- Responds to fluid resuscitation
What are causes of pre-renal failure in AKI?
- Hypovolaemia – blood loss, fluid loss
- Systemic vasodilation – sepsis, cirrhosis, anaphylaxis
- Pre-glomerular vasoconstriction – sepsis, NSAIDs
- Post glomerular vasodilation – Ang2 antagonist, ACE inhibitors
How does the kidney attempt to correct pre-renal failure and what happens if it fails?
- In mild hypo-perfusion, autoregulation ensures renal blood flow preserved
- Dilation of afferent arteriole - prostaglandin
- Constriction of efferent arteriole - RAAS
- If compensatory responses overwhelmed, AKI occurs
- Occurs below 80mmHg or higher if hypertensive
How do ACE inhibitor and NSAIDs affect renal perfusion to cause pre-renal failure?
- NSAIDs acts against vasodilators (prostaglandins)
- ACE inhibitors act against formation of Ang 2
- The intrinsic auto-regulatory mechanism are overridden
What is the pathophysiology in acute tubular necrosis?
- Cells are damaged which cannot be reversed immediately but can be eventually if treated
- Damaged cells cannot reabsorb salt and water efficiently or expel excess water
- Proximal tubule is particularly at risk of ischaemia if pre-renal AKI persists
What are the causes of acute tubular necrosis?
- Ischaemia
- Nephrotoxins
- Sepsis
- Thombotic-microangiopathy
- Acute tubule-interstitial nephritis
What examples of endogenous nephrotoxins?
- Myoglobin
- Urate
- Bilirubin
What are examples of exogenous nephrotoxins?
- Endotoxin
- X-ray
- Drugs
- Poisons
How can myoglobin cause damage to the kidney?
-Due to muscle necrosis leading to rhabdomyolysis. Myoglobin filtered at glomerulus and is toxic to tubule cells. Can also cause obstruction
What can increase myoglobin?
- Crush injury
- AKI in wars and natural disasters
- Drug users (unconscious so don’t move)
- Elderly - fall
What is the pathophysiology of thrombotic microangiopathy?
- Caused by endothelial damage
- Platelet thrombi
- Partial obstruction of small arteries
- Destruction of Red Blood cells
- Leads to micro-angiopathic anaemia
What can cause acute tubule-insterstitial nephritis?
- Toxin induced (Many drugs)
- Infections (Caused by an inflammatory response)
What is the pathophysiology of post renal failure?
- Obstruction with continuous production
- Rise in intraluminal pressure
- Dilatation of renal pelvis (hydronephrosis)
- Decrease in renal function
What are the causes of post renal failure?
- Within the lumen (stones, blod clot, tumours)
- Within the wall (congenital megareter, stricture post TB)
- Pressure from outside (enlarge prostate, tumour, aortic aneurysm, ligation of ureter)
How is AKI managed?
- Treat volume overload (restriction of sodium and water, diuretic)
- Treat hyperkalemia (restrict dietary K, Calcium gluconate)
- Treat acidosis
- Dialysis
When is dialysis used in the AKI?
- High K+ refractory to treatment
- Metabolic acidosis where the sodium bicarbonate is not appropriate
- Fluid overlaod refractory to diuretic
- Signs of uraemia
- Presence of dialysable nephrotoxin
