Acute Urinary Retention (AUR)

Definition

Acute Urinary Retention (AUR) is the sudden and painful inability to pass urine despite having a full bladder. It is a medical emergency requiring prompt intervention to relieve symptoms and prevent complications.

Aetiology

AUR can result from various causes, including:

Obstruction: Benign prostatic hyperplasia (BPH), urethral stricture, bladder stones.
Infections: Severe urinary tract infections (UTIs), prostatitis.
Neurological conditions: Spinal cord injury, multiple sclerosis, diabetic neuropathy.
Medications: Anticholinergics, antihistamines, and opioids.
Surgical procedures: Postoperative swelling or pain, particularly after pelvic surgery.
Others: Severe constipation, blood clots in the urine, trauma to the urinary tract.

Pathophysiology

In AUR, the bladder becomes overdistended due to the inability to void urine. This overdistension can impair bladder muscle contractility and decrease blood flow to the bladder wall, potentially leading to ischemia and further bladder dysfunction. The underlying cause, whether obstructive, infectious, neurological, or pharmacological, disrupts the normal process of urine storage and emptying.

Risk Factors

Age: More common in older adults.
Gender: Males are more commonly affected due to prostate issues.
History of urinary problems: Previous episodes of urinary retention or lower urinary tract symptoms (LUTS).
Medications: Use of drugs that affect bladder function.
Neurological disorders: Conditions that affect the nervous system's control of the bladder.
Surgical history: Recent pelvic or abdominal surgery.

Signs and Symptoms

Inability to pass urine despite a full bladder.
Severe lower abdominal pain and discomfort.
Distended and palpable bladder.
Frequent urge to urinate with little or no output.
Possible associated symptoms: Fever, hematuria (blood in the urine), or signs of infection.

Investigations

Clinical history and physical examination, including abdominal and genital examination.
Bladder scan or ultrasound: To assess bladder volume and post-void residual volume.
Urinalysis: To check for infection, hematuria, or other abnormalities.
Blood tests: Renal function tests, complete blood count (CBC), and electrolytes.
Imaging: Ultrasound of the kidneys and bladder, or CT scan if obstruction or anatomical abnormalities are suspected.
Urodynamic studies: In selected cases to assess bladder function.

Management

Primary Care Management

If the patient is unwell, refer urgently to hospital and then stabilise the patient, ensuring airway, breathing, and circulation (ABCs).
Referral to a specialist (urologist) only if symptoms persist and the patient has been assessed in the hospital and told to go to the GP (if they have not already been referred by hospital doctors).
Management of underlying conditions (e.g., antibiotics for infection, adjustment of medications).
Patient education on recognising symptoms and avoiding factors that may precipitate AUR.

Specialist Management

Further diagnostic evaluation: Cystoscopy, urodynamic studies, and imaging to identify the underlying cause of AUR.
Medical management: Alpha-blockers (e.g., tamsulosin) to relax the bladder neck and prostate.
Surgical intervention: Transurethral resection of the prostate (TURP) for BPH, removal of bladder stones, or treatment of urethral strictures.
Intermittent self-catheterisation: In cases of chronic urinary retention or neurogenic bladder.
Close monitoring: Regular follow-up to assess treatment response and prevent recurrence.

Example Management for Acute Urinary Retention

A patient presenting with acute urinary retention and severe lower abdominal pain should be urgently referred to a hospital for immediate catheterisation to relieve the retention. After initial stabilisation, further investigations such as a bladder scan and urinalysis should be performed to identify the underlying cause. If the patient has persistent symptoms after initial hospital assessment, they may be referred to a urologist for further evaluation and management, including possible surgical intervention if caused by BPH or bladder stones. Regular follow-up is essential to monitor for recurrence and manage any underlying conditions.

References

NICE. (2024). Lower Urinary Tract Symptoms in Men: Management. Retrieved from NICE
NHS. (2023). Acute Urinary Retention. Retrieved from NHS
Abrams, P., et al. (2013). Acute Urinary Retention: What Is the Impact on Patients’ Quality of Life? BJU International.
McNeill, S. A., & Hargreave, T. B. (2004). Investigation and Management of Acute Urinary Retention. BMJ.
Roehrborn, C. G. (2005). Acute Urinary Retention in Men. Reviews in Urology.