Urinary retention

Causes:

Outflow obstruction (most common)
- Mechanical factors
  - Men:
    - BPH
    - Bladder/prostate cancer
    - Urethral stricture
    - Phimosis/paraphimosis
  - Women:
    - Anatomic distortion - can be due to retroverted gravid uterus
  - Both genders
    - Blood clot
    - Urethral calculus
    - Urethral rupture
    - Constipation/faecal impaction
    - Anal pain (haemorrhoidectomy)
    - Drugs (see below)
- Dynamic factors
  - Increased muscle tone within and around urethra
Neurologic impairment
- Spinal cord injuries/infarct/demyelination - see below
- Epidural abscess
- GBS
- Diabetic neuropathy
- Stroke
Inefficient detrusor muscle
- GA/epidural
- Medications (see table below)
Infection
- Prostatitis (esp men who already have BPH)
- UTI (urethritis)

Management

IDC
- If <200mL drained, take out the IDC and observe. That patient probably needs a CT scan too - common masqueraders of retention are AAA, ureteric colic and diverticulitis
- If unable to pass urethral catheter - consider stricture, poor technique, lack of anaesthesia, traumatisation of urethra
- See separate topic - IDC insertion

Post-IDC investigation

Exam - PR, PV, neurologic
Urine MCS
PSA will be elevated regardless during AUR

Post Ix Management

Consider starting duodart
If reversible cause identified, TOV once this is treated
Otherwise d/w appropriate specialist

Complications

Post-obstructive diuresis
- Occurs due to loss of ability to reabsorb salts and water in the distal tubules, secondary to chronic back pressure
- Once the pressure is relieved, the patient has an enormous outflow of salts and water
- These patients are often also anaemic and may require transfusion if Hb <90 (according to Bailey and Love)
- Most patients can just drink more to compensate
- If IV rehydration is required, give hourly chase 50% one half normal saline

Acute neuropathic bladder

Associated with spinal shock which occurs immediately after spinal cord injury. The detrusor cannot contract, the bladder distends and overflow incontinence occurs. If neglected, over-distension will lead to damage and ultimately renal failure.
Need either long-term IDC or intermittent drainage
Neurologic examination to assess level of injury - incomplete lesions may recover somatic and bladder function
Demonstration of intact bulbocavernosus and anal reflexes indicate that the sacral cord and nerves are intact and that reflex bladder contractions are likely to develop to some extent
If there is persistent total loss of reflexes and perineal sensation then either the sacral cord or cauda equina is damaged. In such circumstances an acontractile bladder is likely.
Full urodynamic assessment of bladder function should be undertaken when the injury is stable. Prime aim is to prevent upper tract injury by maintaining good bladder emptying.

Lesions above T10, or those involving sympathetic outflow (T11, T12, L1, L2)

Usually leads to 'upper motor neuron' bladder with reflexes intact but isolated from higher control mechanisms. Such patients are at risk of autonomic dysreflexia.
Bladder contractions are high pressure and ineffective in emptying the bladder. Bladder capacity is usually decreased. Can lead to upper tract damage.
Some patients with low-pressure bladders that empty may be managed with condom drainage. Others will require ISC.
Patients with poor emptying, low bladder capacity and upper tract dilatation require treatment with endoscopic sphincterotomy and condom drainage, and some may require bladder reconstruction.

Damage to sacral centre S2, S3, S4 and cauda equina lesions

Usually leads to 'lower motor neuron' bladder; acontractile detrusor. Abdominal straining can produce reasonable emptying but the mainstay is ISC.
Some may have sensation of filling if T11 and T12 are intact
The bladder capacity may be good, but still high pressure system, with risk of damage to upper tract
Patients who can achieve satisfactory bladder emptying by means of ISC usually have reasonable continence.

Damage to inferior hypogastric plexus

Occurs in 10-15% of patients having radical rectal excisions
Leads to impotence and neurogenic bladder dysfunction
Similar bladder dysfunction to cauda equina lesion
If retention occurs in the post-op period, best to catheterise, then carry out urodynamic investigation to determine the appropriate treatment.

Pharmacologic agents associated with urinary retention

Sympathomimetics (alpha-adrenergic agents)	Ephedrine sulfate (Marax, Tedral)
	Phenylephrine HCl (Neo-Synephrine)
	Phenylpropanolamine HCL (Conlac)
	Pseudoephedrine HCl (Sudafed, Actifed)
Sympathomimetics (beta-adrenergic agents)	Isoproterenol
	Metaproterenol
	Terbutaline
Antidepressants	Imipramine (Tofranil)
	Nortriptyline (Aventyl)
	Amitriptyline (Elavil)
	Doxepin (Adapin)
	Amoxepine (Asendin)
	Maprotiline (Ludiomil)
Antiarrhythmics	Quinidine
	Procainamide
	Disopyramide
Anticholinergics (selected)	Atropine
	Scopolamine hydrobromide
	Clidinium bromide (Quarzan)
	Glycopyrrolate (Robinul)
	Mepenzolate bromide (Cantil)
	Oxybutynin (Ditropan)
	Flavoxate HCl (Urispas)
	Hyoscyamine sulfate (Anaspaz)
	Belladonna
	Homatropine methylbromide
	Propantheline bromide (Probanthine)
	Dicyclomine HCl (Bentyl)
Antiparkinsonian agents	Trihexyphenidyl HCl (Arlane)
	Benztropine Mesylate (Cogentin)
	Amantadine HCl (Symmetrel)
	Levodopa (Sinemet)
	Bromocriptine Mesylate (Parlodel)
Hormonal agents	Progesterone
	Estrogen
	Testosterone
Antipsychotics	Haloperidol (Haldol)
	Thiothixene (Navane)
	Thioridizine (Mellaril)
	Chlorpromazine (Thorazine)
	Fluphenazine (Prolixin)
	Prochlorperazine (Compazine)
Antihistamines (selected)	Diphenhydramine HCl (Benadryl)
	Chlorpheniramine (Chlor-Trimeton)
	Brompheniramine (Dimetane)
	Cyproheptadine (Periactin)
	Hydroxyzine (Atarax, Vistaril)
Antihypertensives	Hydralazine (Apresoline)
	Nifedipine (Procardia)
Muscle relaxants	Diazepam (Valium)
	Baclofen (Lioresal)
	Cyclobenzaprine (Flexeril)
Miscellaneous	Indomethacin (Indocin)
	Carbamazepine (Tegretol)
	Amphetamines
	Dopamine
	Vincristine
	Morphine sulfate and other opioids
	Anesthetic agents