Acute Urinary Retention (AUR) - the sudden inability to pass urine - is a common problem seen in the emergency department, especially in older men. The most common cause of AUR is benign prostatic hypertrophy (BPH) (Curtis). Men in their 70s with moderate or severe urinary symptoms (e.g. urinary frequency, incomplete bladder emptying) have a 3.5% incidence of AUR per year (Jacobsen). Other causes of AUR include additional obstruction etiologies (bladder neck contracture, obstructing tumor), neurological causes (cauda equina) and pharmacological causes (sympathomimetics, anticholinergics) (Curtis). The failure to place a catheter in a patient with AUR can lead to severe discomfort and bladder damage, including atonia or rupture.

Obtaining a sterile urine can be difficult in certain patient populations including the very young, elderly and mentally impaired. When a health care provider is attempting to choose optimal antibiotics, the need to find a source for a suspected infection is important. A urine that is contaminated can lead the provider down the wrong diagnostic track. Acquiring a sterile urine sample can facilitate improved care and a clear diagnosis. Furthermore, in patients who present with symptoms of cauda equina, TUC for residual urine volume may be useful to determine urinary retention, suggesting an actue neurologic bladder (Beeson).

Monitoring a patient's urine output is an easy way to assess a patient's fluid status and ensure an appropriate amount of fluids is being provided to the patient (Simon). It may also allow a clinician to distinguish initially between dehydration, anuria - the inability of the kidney's to produce urine, and AUR.