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Urinary tract obstruction

Urinary tract obstruction. Victor Federico B. Acepcion, MD, FPUA . The Kidney. Basic function: formation of ultrafiltrate that is free of protein with appropriate amount of water, electrolytes, and end products of metabolic pathways to maintain homeostasis. Remaining portion of UT

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Urinary tract obstruction

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  1. Urinary tract obstruction Victor Federico B. Acepcion, MD, FPUA

  2. The Kidney • Basic function: • formation of ultrafiltrate that is free of protein with appropriate amount of water, electrolytes, and end products of metabolic pathways to maintain homeostasis. • Remaining portion of UT • Eliminate and/or store urine

  3. Urine production • Pressure gradient from glomerulus to Bowman capsule • Peristalsis of renal pelvis and ureter • Effects of gravity

  4. Urinary tract obstruction • Common cause of acute and chronic renal failure • Potentially curable form of kidney disease

  5. Definition of terms • Obstructive uropathy • Obstructive nephropathy • Hydronephrosis

  6. Objectives • Define urinary tract obstruction • Incidence • Etiology/pathophysiology • Clinical presentation • Diagnosis • Treatment and management • Pre-hospital/emergency department care

  7. Incidence • Frequency • No data available in unselected populations • 20-35% prevalence in large survey among elderly men • 3.8% (adults); 2.0% (children) postmortem examinations • Sex • No gender difference until 20 years • Women 20-60; Men > 60 • Age • Special considerations in pediatric patients

  8. Etiology • Types of obstruction • Mechanical blockade • Intrinsic • extrinsic • Functional defects • Congenital

  9. Pathophysiology • Unilateral (UUO)? • Bilateral (BUO)? • Obstruction relieved or not? • Time

  10. Global Renal Function Changes • Obstruction can affect hemodynamic variables and GFR • GFR= Kf(PGC-PT-PGC) • RPF= (aortic pressure-renal venous pressure) renal vascular resistance • Influences PGC • Constriction of the afferent arteriole will result in a decrease of PGC and GFR • An increase in efferent arteriolar resistance will increase PGC • Kf- glomerular ultrafiltration coeffecient related to the surface area and permeability of the capillary membrane • PGC- glomerular capillary pressure. Influenced by renal plasma flow and the resistance of the afferent and efferent arterioles • PT- Hydraulic pressure of fluid in the tubule • P- the oncotic pressure of the proteins in the glomerular capillary and efferent arteriolar blood

  11. Triphasic pattern of UUO

  12. Bilateral urinary obstruction (BUO) • No triphasic pattern • Modest increase in RBF after 90 min but between 90 min to 7 hours, RBF is significantly lower than UUO. • Increase renal vascular resistance (RVR) • After 24 hours, low RBF, high RVR same as UUO

  13. Bilateral urinary obstruction (BUO) • Ureteral pressure higher than in UUO • Effective RBF is markedly decreased after 48 hours • GFR is significantly decreased after 48 hours

  14. Summary of UUO and BUO

  15. Pathophysiology Obstructive Uropathy Obstructive Nephropathy

  16. Consequences of urinary tract obstruction • Reduced glomerular filtration rate • Reduced renal blood flow (after initial rise) • Impaired renal concentrating ability • Impaired distal tubular function • Nephrogenic diabetes insipidus • Renal salt wasting • Renal tubular acidosis • Impaired potassium concentration • Postobstructive diuresis

  17. Consequences of urinary tract obstruction • Progressive and permanent changes to the kidney occur • Tubulointerstitial fibrosis • Tubular atrophy and apoptosis • Interstitial inflammation

  18. Diagnosis • History • Pain, renal colic • Inability to void effectively • Alteration in pattern of micturition (anuria, polyuria, nocturia) • Recurrent UTI • New-onset or poorly controlled hypertension • Polycythemia • Recent gynecologic or abdominal surgery

  19. History • Medication history • Antihistamines, antipsychotics, antidepressants • Ethylene glycol, indinavir, methotrexate, phenylbutazone, or sulfunamides • Methysergide or other natural-occurring ergotamines • Occupational exposure history • Textile manufacturers, shipyard workers, roofers or asbestos miners (retroperitoneal fibrosis) • Textile workers, rubber manufacturing workers, leather workers, painters, hairdressers, drill press workers (bladder cancer)

  20. Physical Examination • Signs of dehydration and intravascular volume depletion • Peripheral edema, hypertension, signs of congestive heart failure • Palpable kidney or bladder • Enlargement of pelvic organs (eg. Prostate, uterus) • Examination of external urethra for phimosis, meatal stenosis

  21. Normal kidney

  22. Treatment and management • Prehospital Care • Pulmonary edema • Salt and water retention • hypovolemia

  23. Treatment and management • Emergency department care • Investigate and begin treatment of potentially life-threatening complications • Pulmonary edema • Hypovolemia • Urosepsis • Hyperkalemia

  24. Treatment and management • Overriding goal of treatment: reestablishment of urinary flow • Transurethral bladder catheterization • Diagnostic and therapeutic • No urine output = investigate upper tract

  25. Treatment and management • Large PVR = obstruction below the bladder • Fractionating urine removal (?) • Christensen, et al. concluded that fractionating urine removal in bladder obstruction is unjustified • Hematuria and bladder spasm • Gould, et al. : hematuria correlated strongly with degree of bladder wall damage prior to relief of obstruction and not with rate of bladder emptying • Urine should be drained completely and rapidly from an obstructed bladder • Prolonged urine stasis only predisposes to UTI, urosepsis and renal failure

  26. Treatment and management • Calculi – most common causes of unilateral ureteral obstruction • 90% pass spontaneously (calculi <5.0-7.0 mm) • Surgical drainage necessary if with unrelenting pain, UTI, persistent obstruction, progressive loss of renal function • Position of stone determines preferred method of removal

  27. Treatment and management • Bilateral ureteral obstruction – always asymmetric process • mid to proximal ureter – percutaneous nephrostomy • Distal obstruction – cystoscopic placement of ureteral stent • Intrarenal obstruction secondary to crystals or protein casts - hydration

  28. Treatment and management • Consultations • UROLOGIST – when transurethral catheter cannot provide adequate drainage and surgical drainage and removal of obstruction is necessary • NEPHROLOGIST – when emergent hemodialysis is necessary

  29. Treatment and management • Further Inpatient care • Decision to admit depends on the need for invasive surgical drainage procedure and complications of obstruction • Replacement of electrolyte disturbances • Further Outpatient care • Depending on specific complications of obstruction, relief of bladder neck obstruction requires prompt follow-up care with a urologist for definitive therapy.

  30. Prognosis • With relief of obstruction • Reversible or irreversible damage? • Obstruction NOT relieved • Complete or incomplete? • Bilateral or unilateral? • Presence or absence of infection

  31. Summary • UTO is an important urologic disorder and a common cause of acute and chronic renal failure • Multiple causes, high clinical suspicion and acumen necessary • UTO is a potentially reversible process • Prompt recognition • Prompt treatment • Prompt consultation/referral

  32. Thank You

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