Causes and investigation of urinary retention in palliative care

Urinary retention is the inability to empty the bladder completely. It is caused by either obstruction of the bladder outlet or urethra, or reduced bladder detrusor muscle function. It may be preceded by a history of increasing difficulty with urination (eg frequency, nocturia, incontinence, poor flow, hesitancy, infection).

Acute urinary retention is complete inability to urinate. Accumulation of urine causes bladder distension, which is painful and distressing for the patient and may cause other complications (eg hypertension)Serlin, 2018.

Chronic urinary retention is painless and therefore more insidious. It can present with overflow urinary incontinence, acute-on-chronic urinary retention, lower abdominal mass, urinary tract infection or kidney failureSerlin, 2018.

Causes of acute and chronic urinary retention in patients with palliative care needs include:

• decreased mobility
• anticholinergic effects of drugs (including opioids) causing decreased contraction of the bladder detrusor muscle—rationalise and stop these drugs if possible
• severe constipation causing extrinsic compression of the bladder—manage with laxatives as appropriate (see Constipation in palliative care)
• spinal cord compression of the nerves innervating the bladder—this is particularly important in a patient with cancer if they are known to have spinal bone metastases; assess, investigate and treat urgently, if appropriate (see Spinal cord compression or injury in palliative care)
• haematuria and clot retention (see Haematuria in palliative care).

Benign prostatic hyperplasia (BPH) can also cause acute and chronic urinary retention in patients with palliative care needs.

In addition to abdominal examination, a bedside ultrasound bladder scan is a simple and noninvasive investigation that may be used to confirm the presence of urinary retention.