Urinary Retention

Urinary Retention Definition Acute: New onset inability to pass urine Chronic: painless inability to pass urine Long standing Hence bladder densensitation Minimal discomfort despite potential large intra-vesicular volumes Epidemiology More common in older males Due to prostate enlargement Causes Obstructive causes BPH Most common cause in males Ureteral strictures Prostate cancer UTIs -> ureteral sphincter closes Constipation -> urethra compression Severe pain Acute retention Neurological – both acute and chronic Peripheral neuropathy Pelvic surgery -> Iatrogenic nerve damage Motor neuron diseases MS PD DSD Medications Anti-muscarinic Spinal or epidural anaesthesia Can cause both high- and low-pressure urinary retention depending on how that medication affects the kidney Pelvic organ prolapse chronic High Pressure Urinary Retention vs Low Pressure Urinary Retention Pressure Causes High Pressure Low Pressure (more common) Detrusor muscle pressure remains high and increases with filling Bladder pressure stays within normal limits despite large residual volumes Bladder struggling against a severe blockage Weak bladder muscle PBH Structure Stones Kidney Impact Poor contractions from nerve and muscle failure Diabetes Spinal cord injury Leads to hydronephrosis, hydroureter and Upper UT is usually unaffected potential renal failure/impairment Nocturnal enuresis Tense palpable bladder Large post-voidal residual (PVR) Hypertension Symptoms Normal kidney function Leg oedema Can be painless Signs of renal impairment Elevated renal Cr Urgency Medical emergency Can be managed with long term catheterisation Needs prompt drainage via a long-term catheter to prevent permanent kidney damage Trial without catheter is usually avoided esp. if there are signs of high pressure due to a risk of postobstructive diuresis How to differentiate between high and low urinary retention Bloods U&E, Cr and GFR -> kidney damage -> high pressure Renal tract ultrasound Hydronephrosis -> suggests high pressure retention Urodynamic studies With pressure flow studies Gold standard Cystoscopy Examines the inside of the bladder and urethra Identifies renal impairment, infections or prostatic enlargement Clinical features History Physical Exam Inability to pass urine Suprapubic pain and discomfort Acute Palpably distended bladder Painless Suprapubic tenderness chronic Features suggestive of an infective cause: Significant residual volumes Fever Recent change to medications Rigors Worsening voiding LUTS Lethargy Nocturnal enuresis DRE Worse at night Perform in older patients Overflow incontinence Assessment of prostate enlargement or constipation Reduced sphincter tone Investigations Bloods For all patients Routines: FBC CRP U&Es CSU Evidence of infection Post-void bladder scan Shows the volume of retained urine Helps confirm diagnosis Catheterised specimen or urine Post catheterisation Ultrasound scan Patients with features of high-pressure retention Assesses for hydronephrosis If this is the diagnosis -> repeat imaging needed a few weeks after treatment to ensure resolution Management of Acute Urinary Retention Initial Management Definitive Management Patients with a large retention volume Probs have a chronic element to their retention Immediate urethral catheterisation Need to be done urgently Need to be monitored post-catheterisation for evidence of post-obstructive diuresis Look for evidence of high-pressure urinary retention If no evidence of renal impairment Trial without catheter Resolves retention Catheter removed after cause of retention Allows for measurement of the volume drained If patient voids successfully with minimal residual volume post-catheterisation Treat the underlying cause accordingly TWOC is considered successful If an infective cause If fails -> two more can be attempt Antibiotics Will need a long-term catheter until definitive management can occur Review patient medications All men with a history of chronic lower UT symptoms Alpha-1 adrenoreceptor antagonist Management of Chronic Retention Immediate Definitive If high post void volumes or evidence of high-pressure retention Long term catheter Alternative to long term catheter Intermittent self-catheterisation For patients who wish to avoid a long-term catheter Patients taught how to catheterise at regular intervals E.g. every 4 to 6 hours Required good manual dexterity and patient compliance Not suitable for all patients If high post void volumes Urine output monitoring for post-obstructive dieresis Should not undergo a TWOC especially if there is evidence of high-pressure chronic retention Due to a concern of repeated renal injury Features requiring immediate referral Renal impairment Complications If presents and is treated early Few complications related to retention occur If chronic -> AKI -> CKD Multiple episodes of retention -> renal scaring Urinary retention -> UTIs and bladder calculi Urinary stasis -> infections and renal stones Management of underlying cause