Acute urinary retention

What it is

Urinary retention is overdistention of the bladder caused by impaired detrusor contractility or by bladder outlet obstruction, and it leads to urine leakage by overflow. As a type of chronic incontinence, overflow accounts for 5 percent of patients with chronic incontinence.

Retention is the end of the obstructive half of the lower urinary tract symptoms. Obstructive: weak stream, incomplete urination; difficulty to initiate - hesitancy, to maintain - intermittency, to terminate - post micturition dribbling; and then urinary retention, which is absence of urine flow with a palpable bladder. Irritative is the other half: urgency, frequency, nocturia, incontinence, dysuria. For the bladder outlet obstruction behind it, the GOLD standard test is urodynamic studies.

Causes and risk

• Anticholinergic medications, benign prostatic hyperplasia, pelvic organ prolapse, diabetes mellitus, multiple sclerosis and spinal cord injuries.
• The chronic urinary retention behind overflow leakage may come from diabetic neuropathy, spinal cord injury, or obstruction such as BPH.
• Overflow is more common in older persons, but it can also occur in young adults as a manifestation of neurologic disorders, such as multiple sclerosis.

The tricyclic antidepressants are the drug group named here, and they are not all alike. Their commonly reported adverse effects are generally anticholinergic, and urinary retention sits on that list beside blurred vision, cognitive changes, constipation, dry mouth, orthostatic hypotension, sedation, sexual dysfunction and tachycardia. The material then ranks the drugs themselves from fewest adverse effects to most: desipramine, nortriptyline, imipramine, doxepin, amitriptyline. So where a tricyclic has caused the retention, amitriptyline is the one at the far end of that arrow and desipramine the one at the near end.

One setting turns new retention into an emergency of another organ. In a patient with low back pain, new urinary retention or overflow incontinence is a red flag finding of strong evidence for cauda equina syndrome, listed with progressive motor or sensory loss and new fecal incontinence among the historic findings. The examination findings that go with it, also of strong evidence, are saddle anesthesia, loss of anal sphincter tone, and significant motor deficits encompassing multiple nerve roots.