Acute urinary retention (AUR) is the painful inability to pass urine, leading to fluid accumulation within the bladder. This condition is a time-sensitive urological emergency demanding immediate medical intervention. The buildup of urine causes discomfort and can lead to complications if not relieved quickly. AUR is most frequently observed in older men, but it can affect any individual.
Recognizing Symptoms and Immediate Action
The onset of AUR is marked by lower abdominal pain. The individual experiences a powerful urge to urinate but is unable to produce a significant stream.
A physical examination often reveals a firm, palpable distention in the suprapubic area, indicating an overfilled bladder. Ignoring these signs can lead to distress and damage to the urinary system.
The person must immediately seek professional medical care. The most appropriate action is to call emergency medical services or proceed directly to the nearest emergency department.
Timely intervention is necessary to relieve pain and prevent complications such as kidney injury, which occurs from the back-up of pressure into the upper urinary tract. Medical personnel will confirm the diagnosis and initiate decompression.
Underlying Mechanisms and Risk Factors
The causes of AUR fall into obstructive and non-obstructive categories. Obstructive causes involve a physical blockage preventing urine flow. The most common obstructive cause in men is benign prostatic hyperplasia (BPH), where the enlarged prostate gland compresses the urethra.
Other mechanical obstructions include urethral strictures (narrowing of the urethra) or bladder stones blocking the bladder neck. Severe constipation can also compress the urethra externally.
The non-obstructive causes relate to issues with the nerves or the bladder muscle, preventing effective contraction and emptying. Nerve dysfunction (neurogenic bladder) results from conditions like diabetic neuropathy or spinal cord injury. These issues disrupt the communication pathway, leading to inadequate detrusor muscle tone.
Certain medications are risk factors for non-obstructive retention (pharmacologic retention). Drugs with anticholinergic properties, such as antidepressants or antihistamines, interfere with the signals that prompt bladder muscle contraction. Anesthesia can also temporarily impair nerve function, leading to an inability to void post-procedure.
Emergency Decompression Procedures
Immediate management focuses on prompt and complete decompression of the distended bladder. The standard method is the insertion of a Foley catheter, a flexible tube passed through the urethra into the bladder.
If urethral access is impossible (e.g., due to severe strictures or prostate surgery), a suprapubic catheter is used. This involves placing the catheter directly into the bladder through a small incision in the lower abdominal wall, bypassing the urethra for reliable drainage.
Once the catheter is placed, the urine drains freely. Current evidence supports rapid, complete decompression of the bladder, contrary to older practices that suggested gradual draining. Rapid draining has not been shown to increase the risk of complications.
Medical staff monitor for post-obstructive diuresis (POD) immediately after decompression. POD is an excessive, rapid production of urine, often defined as output exceeding 200 milliliters per hour for two consecutive hours. Pathologic POD can lead to fluid loss, dehydration, and electrolyte imbalances if not carefully managed.
Long-Term Management of Recurrence
After the immediate crisis, the focus shifts to treating the underlying cause to prevent recurrence. For BPH cases, long-term treatment often begins with medications.
Alpha-blockers (e.g., tamsulosin) relax muscles in the prostate and bladder neck to improve urine flow. 5-alpha reductase inhibitors (5-ARIs) like finasteride shrink the prostate gland over time. Combining these two types of medications is a common strategy.
If medication is ineffective, surgical options may be considered. The traditional procedure is a Transurethral Resection of the Prostate (TURP), which removes excess prostate tissue to widen the urinary channel. Minimally invasive surgical treatments (MiSTs), such as the prostatic urethral lift, are also available.
For patients with neurogenic bladder, the long-term strategy involves clean intermittent self-catheterization (ISC). This technique requires the patient to insert a flexible catheter several times a day to empty the bladder completely. ISC is the preferred method for managing chronic retention due to nerve issues.