Acute urinary retention (AUR) in men is defined as the sudden, usually painful, inability to pass urine despite a full bladder. This condition is a medical emergency requiring immediate attention to prevent severe complications, including potential kidney damage. Although AUR can affect men of any age, the risk increases substantially with advancing years, particularly after age 60. Approximately one in ten men over the age of 70 will experience an episode of AUR. The inability to empty the bladder causes significant lower abdominal discomfort and distension.
Immediate Steps and Emergency Protocols
The most important action when acute urinary retention occurs is to immediately seek professional medical care by calling emergency services or going to the nearest emergency department. Attempting to self-diagnose or manage the inability to urinate can delay definitive treatment and increase the risk of complications. Because the bladder cannot empty, pressure quickly builds, which can threaten kidney function if not relieved.
While awaiting emergency medical personnel, certain comfort measures can be attempted to potentially induce temporary bladder muscle relaxation. A warm bath or shower may help to relax the pelvic floor and sphincter muscles, which could allow a small amount of urine to pass. Changing position, such as standing or sitting, may also be mildly helpful.
Avoid attempting to force urination by straining, as this action will not overcome a physical obstruction and can increase pain. Do not increase fluid intake in an attempt to “flush out” the system; adding more fluid to an already over-distended bladder will only worsen the pain and increase the pressure on the upper urinary tract. Self-catheterization attempts should also be avoided, as this carries a high risk of introducing infection or causing traumatic injury to the urethra.
Underlying Causes of Acute Urinary Retention
The causes of acute urinary retention in men are typically categorized into two broad groups: obstructive (physical blockage) and non-obstructive (nerve or muscle dysfunction).
Obstructive Causes
The primary cause of acute urinary retention in men is Benign Prostatic Hyperplasia (BPH), or non-cancerous enlargement of the prostate gland. The prostate surrounds the urethra, and as it grows, it squeezes the urinary tube, creating a mechanical obstruction at the bladder neck. BPH is responsible for over half of all acute urinary retention cases.
Other physical blockages can also prevent urine flow, including a urethral stricture, which is a narrowing of the urethra usually caused by scar tissue from inflammation or injury. Prostate cancer, while less common than BPH, can also cause severe obstruction by tumor growth. Bladder stones can move and physically block the opening of the bladder.
Severe constipation or a large fecal impaction can also present as an obstructive cause. The mass of stool in the rectum can physically compress the urethra or the bladder neck from the outside. Infections such as acute prostatitis can cause the prostate gland to swell rapidly, leading to a sudden narrowing of the urinary passage.
Non-Obstructive Causes
Non-obstructive causes involve issues with the nerves that control the bladder muscle (detrusor) or the sphincter muscles. Neurological conditions disrupt the signals between the brain and the bladder, preventing the detrusor muscle from contracting strongly enough to empty the bladder. Such conditions include spinal cord injuries, stroke, multiple sclerosis, and Parkinson’s disease.
A number of common medications can also interfere with bladder muscle function, leading to pharmacologic retention. Drugs with anticholinergic properties, such as certain antihistamines and older antidepressants, can cause the detrusor muscle to relax excessively. Alpha-adrenergic agonists found in many over-the-counter cold and decongestant medications can tighten the bladder neck sphincter. Opioid pain medications are another frequent culprit, as they can directly impact the nervous system’s control over bladder emptying.
Medical Diagnosis and Treatment Interventions
Upon arrival at a medical facility, the immediate priority is to confirm the diagnosis and relieve the pressure within the bladder. A physical examination will often reveal a distended and tender area above the pubic bone, indicating a full bladder. The precise volume of retained urine is measured quickly and non-invasively using a bedside bladder scanner, a specialized ultrasound device.
Immediate treatment involves bladder decompression, achieved by inserting a catheter to drain the accumulated urine. A standard Foley catheter is usually placed through the urethra. If a urethral obstruction is impassable, a suprapubic catheter may be temporarily inserted through the abdominal wall directly into the bladder. The volume of urine drained is carefully monitored, as the sudden release of a large amount of retained urine (often over 1,000 milliliters) carries a risk of post-obstructive diuresis.
Diagnostic testing performed alongside decompression includes blood work to assess kidney function, specifically looking at levels of creatinine and blood urea nitrogen. A urine sample is also collected from the catheter to check for infection. For older men, a blood test for Prostate-Specific Antigen (PSA) and a digital rectal exam may be performed to assess the size and texture of the prostate gland.
Long-term management focuses on treating the underlying cause of the retention. If BPH is the cause, medication such as alpha-blockers like tamsulosin can be started immediately to relax the muscle fibers in the prostate and bladder neck. If medication is the trigger, the drug is typically discontinued or adjusted to a different class. When the underlying obstruction is severe or recurrent, definitive procedures may be necessary. This can include surgical options like Transurethral Resection of the Prostate (TURP) or newer, less invasive procedures like the prostatic urethral lift, all aimed at opening the urinary channel.