--- module: 051-02 language: en chapter: 51 title: "Urinary Tract Disease, Obstruction, Stones, Continence, and Urological Assessment" module_title: "Urinary drainage physiology, infected obstruction, haematuria, and bladder function" source_sha256: 0d431e294a161783d207d505119f0765285762b2eff4c088ca0197689caae966 --- # Drainage, infected obstruction, haematuria, bladder function ## Low-pressure drainage protects kidneys ### Obstruction anywhere from pelvis to urethra #### Fixed or intermittent, unilateral or bilateral #### Anatomical or functional ### Symptoms do not measure severity #### Slow bilateral obstruction may be painless #### Small moving stone causes extreme colic ### Urgent questions #### Infection trapped behind obstruction #### Both kidneys or solitary kidney threatened #### Bladder pressure damaging upper tract ## Ureteric colic and infected obstruction ### Peristalsis and pressure above mobile obstruction #### Flank pain migrating toward groin #### Microscopic haematuria supports, not required ### Red flags: fever, hypotension, anuria #### Infection, infarction, rupture, renal threat ### Infected obstruction is a source-control emergency #### Pressure cuts antibiotic delivery and clearance #### Rapid bacteraemia and septic shock #### Bladder urine may be deceptively sterile ### Resuscitate, antibiotics, stent or nephrostomy #### Stone removal waits for infection control ### Forced fluid worsens pain or overload ## Stone formation and imaging ### Low urine volume concentrates every solute ### Sodium intake raises urinary calcium ### Low dietary calcium leaves oxalate unbound ### Citrate complexes calcium, inhibits crystals ### Stone types #### Uric acid precipitates in acidic urine #### Cystine reflects inherited transport #### Urease infection forms branching struvite ### Non-contrast computed tomography finds stones, alternatives ### Ultrasound first in pregnancy #### May miss early obstruction or small stones ### Intervene for persistent obstruction or infection ## Bladder control and retention ### Emptying: detrusor contracts, outlet relaxes ### Storage: sympathetic and somatic closure #### Parasympathetic activity restrained ### Pontine and cortical coordination ### Many causes of residual urine #### Prostate size alone cannot define mechanism ### Chronic high-pressure retention can be silent #### Until kidney failure or overflow leakage ### Bedside ultrasound avoids needless catheters ### Blind attempts cause false passages, stricture ## Anuria and post-obstructive diuresis ### Production failure versus drainage failure #### Check catheter kinking, blockage, bag height ### Empty bladder with bilateral hydronephrosis #### Suggests upper-tract obstruction ### Empty bladder without hydronephrosis #### Circulatory failure or parenchymal injury #### Early obstruction may show slight dilatation ### Post-obstructive diuresis #### Retained sodium and water, failed concentration #### Matching every millilitre perpetuates diuresis #### Under-replacement causes hypovolaemia, shock ## Symptoms and urinalysis ### Storage, voiding, post-void: treatment differs ### Frequency from small capacity or high output ### Nocturia without bladder disease #### Sleep apnoea, heart failure, oedema mobilisation ### Frequency-volume chart reveals mechanism ### Dipstick blood detects haem pigment #### Microscopy confirms red cells ### Leukocyte esterase is not proof of bacteria ### Nitrite false negatives with frequent voiding ## Infection and catheters ### Syndrome plus testing, not culture alone ### Fever, flank pain: tissue-penetrating therapy ### Mimics: prostatitis, urethritis, stones, malignancy ### Empirical antibiotics without culture select resistance ### Catheter biofilm makes bacteriuria expected #### Cloudiness and odour do not prove infection #### Culture from port, never from bag ## Haematuria and tumours ### Glomerular: protein, dysmorphic cells, casts ### Urological: clots, stone pain, visible lesions ### Anticoagulation amplifies, does not end workup ### Painless visible blood warns even if transient ### Imaging misses flat or small bladder lesions #### So combine with cystoscopy ### Clot retention needs irrigation or endoscopy ### Kidney tumours: mass, anaemia or erythrocytosis ## Incontinence and neurogenic dysfunction ### Stress, urgency, overflow, functional, fistula #### Stereotype-based treatment often fails ### Pelvic-floor training needs dose and months ### Antimuscarinics worsen cognition and retention ### Neurogenic care protects kidneys #### Symptoms may underestimate pressure #### Intermittent catheterisation, low-pressure storage ## Discharge safety ### Explain urgent return signs ### Catheter indication, removal date, owner ### Symptom resolution does not prove clearance ### Confirm kidney function and cause resolved