Acute Urinary Retention

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PatientPlus articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.

See also separate articles Chronic Urinary Retention and Catheterising Bladders

Acute urinary retention (AUR) is the sudden inability to pass urine. It is usually painful and requires emergency treatment with a urinary catheter.

Causes of urinary retention

These are numerous and can be classified as:[1]

Infectious and inflammatory:

Up to 10% AUR episodes are thought to be attributable to drugs. Those known to increase risk include:

  • Anticholinergics (eg, antipsychotic drugs, antidepressant agents, anticholinergic respiratory agents).
  • Opioids and anaesthetics.
  • Alpha-adrenoceptor agonists.
  • Benzodiazepines.
  • Non-steroidal anti-inflammatory drugs.
  • Detrusor relaxants.
  • Calcium-channel blockers.
  • Antihistamines.
  • Alcohol.

More often causing chronic retention but may cause AUR:


  • In men - penile trauma, fracture, or laceration.
  • In women - postpartum complications (increased risk with instrumental delivery, prolonged labour and Caesarean section),[2]urethral sphincter dysfunction (Fowler's syndrome).
  • In both - pelvic trauma, iatrogenic, psychogenic.

BPH is by far the most common cause of urinary retention.

AUR is often encountered postoperatively and the reasons for this are multifactorial:

  • Pain.
  • Traumatic instrumentation.
  • Bladder overdistension.
  • Drugs (particularly opioids).
  • Iatrogenic (eg, suburethral sling procedures for stress incontinence[3], posterior colporrhaphy[4]).
  • Decreased mobility and increased bed rest.

It is a reasonably common emergency with an incidence of primary AUR in England of approximately 3/1,000 men per annum.[5] It is ten times more common in men than in women and highest in men aged over 70.[6] 

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Usually the diagnosis is self-evident. The patient is very uncomfortable and unable to pass urine with a tender, distended bladder. However, it is necessary to consider the diagnosis in those unable to describe symptoms - eg, unconscious patients following trauma. History and examination should be directed towards determining a cause for the AUR. Whilst BPH is very common, rarer but serious causes such as cauda equina or cord compression must not be missed.[7] See also separate articles Genitourinary History and Examination (Male) and Genitourinary History and Examination (Female).


  • Nature and duration of current symptoms - eg, anuria, pain.
  • Any other associated symptoms - eg, fever, weight loss, sensory loss, weakness.
  • Enquire regarding previous episodes of retention and history of lower urinary tract symptoms (LUTS).
  • Consider precipitants - eg, alcohol consumption, recent surgery, urinary tract infection (UTI), constipation, large fluid intake, cold exposure or prolonged travel.
  • Past medical history - eg, neurological conditions.
  • Check medication (both prescribed and over-the-counter) for agents known to cause urinary retention.


  • General - look for fever and signs of infection and systemic illness.
  • Abdominal - a tender enlarged bladder with dullness to percussion well above the symphysis pubis, often almost to the level of the umbilicus.
  • Genitourinary:
    • In men, look for phimosis or meatal stenosis, as well as urethral discharge and genital vesicles.
    • In women, look for evidence of:
      • Vulval or vaginal inflammation or infection.
      • Cystocele, rectocele or uterine prolapse.
      • Pelvic mass (eg, retroverted gravid uterus, uterine fibroid, gynaecological malignancy).
  • Per rectum (PR) - check anal tone, prostatic size, nodules, tenderness, etc and exclude faecal impaction.[6] 
  • Neurological - look for evidence of prolapsed disc or cord compression by checking lower limb power and reflexes as well as perineal sensation.

Distinguish from chronic urinary retention:

  • AUR is usually painful, whilst slowly obstructing pathological processes tend to be relatively pain-free.
  • Prostatic hypertrophy may be associated with obstruction uropathy that is relatively painless but frequently comes to light when a superimposed acute obstruction occurs preventing effective urination ('acute-on-chronic' urinary retention). For about 50% of those with AUR, the acute retention was their first symptom of underlying prostatic hyperplasia.[8]
  • Urinalysis - check for infection, haematuria, proteinuria, glucosuria.
  • MSU.
  • Blood tests:
    • FBC.
    • U&E, creatinine, eGFR.
    • Blood glucose.
    • Prostate-specific antigen (PSA). NB: this is elevated in the setting of AUR so is of limited use at this stage.[6] 
  • Imaging studies:
    • Ultrasound - commonly used, as it can provide a measure of post-void residual urine as well as looking for hydronephrosis and other structural abnormalities of the renal system.
    • CT scan - used to look for pelvic, abdominal or retroperitoneal mass causing extrinsic bladder neck compression.
    • MRI/CT brain scan - used to look for intracranial lesions (eg, tumour, stroke, MS).
    • MRI scan of the spine - used to look for disc prolapse, cauda equina syndrome, spinal tumours, spinal cord compression, MS.
    • Investigations such as cystoscopy, retrograde cystourethrography or urodynamic studies may also be undertaken depending on the suspected cause of retention.

Initial management

  • Immediate and complete bladder decompression, usually with a Foley® urinary catheter. This can be undertaken in a community or hospital setting. The patient should then be referred to the urologists for longer-term management.
  • If this fails or is contra-indicated (eg, urethral trauma or stenosis), refer to a urologist. Alternatives include angulated Coude® catheters or suprapubic catheters.
  • A Cochrane review suggested that the use of silver alloy indwelling catheters for catheterising hospitalised adults short-term (<14 days) reduced the risk of catheter-acquired UTI[9] but subsequent studies have found that they are not cost-effective.[10] 
  • Pharmacological treatment for postoperative retention (eg, cholinergics, intravesicle prostaglandin) has been explored as an alternative to catheterisation but further studies are required.[11] 

As for any intimate examination, the patient should always have the option of a chaperone, although many will decline.[12][13]

Secondary management

This is dependent on the cause of the AUR. For AUR caused by prostatic enlargement:

  • Until recently, this consisted almost exclusively of prostatic surgery within a few days (emergency surgery) or a few weeks (elective surgery) of a first AUR episode. It is known, however, that there is greater morbidity and mortality associated with emergency surgery and that morbidity increases with prolonged catheterisation.
  • A more conservative approach involving the use of a trial without catheter (TWOC) has steadily become adopted as standard practice. This involves removing the catheter after 1-3 days: patients are able to void in 23-40% of cases and surgery, if needed, can be planned for a later date.[14] In the UK, this has resulted in a progressive decrease in the number of surgical procedures following a first episode of AUR but a slight increase in the AUR recurrence rate. Such an approach requires impeccable communication between the hospital services and primary care.
  • Alpha-1 blockers given before catheter removal increase the chances of a successful TWOC.[15] 
  • A high PSA level and post-void residual urine volume, and limited response to alfuzosin treatment after a first AUR episode managed conservatively, may help to identify patients at risk of an unfavourable outcome.[16] 
  • UTIs.
  • Renal failure.
  • Post-obstructive diuresis (marked natriuresis and diuresis with electrolyte disturbance, including hypokalaemia, hyponatraemia, hypernatraemia, and hypomagnesaemia).
  • Post-retention haematuria - 2-16% in one study after rapid decompression via a catheter and usually self-limiting.[17]  

There is an increased mortality rate associated with AUR:[18] 

  • In one study of 100,067 men with spontaneous AUR, the one-year mortality was 4.1% in men aged 45-54 years and 32.8% in those aged 85 years and over.
  • In men aged 75-84 years with spontaneous AUR - the most prevalent age group - the one-year mortality was 12.5% in men without comorbidity and 28.8% in men with comorbidity.
  • The mortality rate associated with AUR increases strongly with age and comorbidity. There is a high prevalence of comorbidities such as CVD, diabetes and chronic pulmonary disease in those with urinary retention.
  • The use of less invasive methods to treat underlying causes (eg, prostatic stents) may help to improve the prognosis of men with comorbidities.

Prevention of AUR in men with BPH may be achieved by long-term medical treatment (5-alpha reductase inhibitors alone or in combination with alpha-blockers).[19] One study suggested that delaying 5-alpha reductase inhibitor therapy resulted in an increased risk of developing AUR.[20] Some studies have developed algorithms for predicting when men with BPH are likely to develop AUR, based on variables such as selective alpha-1 blockers, prostate volume, PSA level, and maximal flow rate.[21] 

Further reading & references

  1. Selius BA, Subedi R; Urinary retention in adults: diagnosis and initial management. Am Fam Physician. 2008 Mar 1;77(5):643-50.
  2. Lim JL; Post-partum voiding dysfunction and urinary retention. Aust N Z J Obstet Gynaecol. 2010 Dec;50(6):502-5. doi: 10.1111/j.1479-828X.2010.01237.x. Epub 2010 Nov 2.
  3. Patel BN, Kobashi KC, Staskin D; Iatrogenic obstruction after sling surgery. Nat Rev Urol. 2012 Jun 5. doi: 10.1038/nrurol.2012.110.
  4. Book NM, Novi B, Novi JM, et al; Postoperative voiding dysfunction following posterior colporrhaphy. Female Pelvic Med Reconstr Surg. 2012 Jan-Feb;18(1):32-4.
  5. Cathcart P, van der Meulen J, Armitage J, et al; Incidence of primary and recurrent acute urinary retention between 1998 and 2003 in England. J Urol. 2006 Jul;176(1):200-4; discussion 204.
  6. Kuppusamy S, Gillatt D; Managing patients with acute urinary retention. Practitioner. 2011 Apr;255(1739):21-3, 2-3.
  7. Lavy C, James A, Wilson-MacDonald J, et al; Cauda equina syndrome. BMJ. 2009 Mar 31;338:b936. doi: 10.1136/bmj.b936.
  8. Verhamme KM, Sturkenboom MC; Mortality in men admitted to hospital with acute urinary retention. BMJ. 2007 Dec 8;335(7631):1164-5. Epub 2007 Nov 8.
  9. Schumm K, Lam TB; Types of urethral catheters for management of short-term voiding problems in hospitalised adults. Cochrane Database Syst Rev. 2008 Apr 16;(2):CD004013.
  10. Desai DG, Liao KS, Cevallos ME, et al; Silver or nitrofurazone impregnation of urinary catheters has a minimal effect on uropathogen adherence. J Urol. 2010 Dec;184(6):2565-71.
  11. Buckley BS, Lapitan MC; Drugs for treatment of urinary retention after surgery in adults. Cochrane Database Syst Rev. 2010 Oct 6;(10):CD008023.
  12. Maintaining boundaries - guidance for doctors; General Medical Council, 2006
  13. Sinclair AM, Gunendran T, Pearce I; Use of chaperones in the urology outpatient setting: a patient's choice in a "patient-centred" service. Postgrad Med J. 2007 Jan;83(975):64-5.
  14. Emberton M, Fitzpatrick JM; The Reten-World survey of the management of acute urinary retention: preliminary results. BJU Int. 2008 Mar;101 Suppl 3:27-32.
  15. Fitzpatrick JM, Desgrandchamps F, Adjali K, et al; Management of acute urinary retention: a worldwide survey of 6074 men with benign prostatic hyperplasia. BJU Int. 2012 Jan;109(1):88-95. doi: 10.1111/j.1464-410X.2011.10430.x. Epub 2011 Nov 25.
  16. Fitzpatrick JM, Kirby RS; Management of acute urinary retention. BJU Int. 2006 Apr;97 Suppl 2:16-20; discussion 21-2.
  17. Naranji I, Bolgeri M; Significant upper urinary tract hematuria as a rare complication of high-pressure chronic retention of urine following decompression: a case report. J Med Case Rep. 2012 Aug 22;6(1):254.
  18. The epidemiology and management of acute urinary retention: a study based on Hospital Episode Statistics and systematic literature review. Doctoral thesis, UCL (University College London)
  19. Shin TJ, Kim CI, Park CH, et al; alpha-blocker monotherapy and alpha-blocker plus 5-alpha-reductase inhibitor combination treatment in benign prostatic hyperplasia; 10 years' long-term results. Korean J Urol. 2012 Apr;53(4):248-52. Epub 2012 Apr 18.
  20. Naslund M, Eaddy MT, Hogue SL, et al; Impact of delaying 5-alpha reductase inhibitor therapy in men on alpha-blocker therapy to treat BPH: assessment of acute urinary retention and prostate-related surgery. Curr Med Res Opin. 2009 Nov;25(11):2663-9.
  21. Slawin KM, Kattan MW, Roehrborn CG, et al; Development of nomogram to predict acute urinary retention or surgical intervention, with or without dutasteride therapy, in men with benign prostatic hyperplasia. Urology. 2006 Jan;67(1):84-8.

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

Original Author:
Dr Chloe Borton
Current Version:
Peer Reviewer:
Dr Adrian Bonsall
Document ID:
12130 (v2)
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