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Emergency and Acute Medicine - Urinary Retention
Urinary retention is the sudden or chronic inability to empty the bladder adequately. Acute urinary retention refers to the abrupt inability to void spontaneously and occurs most often in men older than 60 years. In the emergency department, the most common cause is benign prostatic hyperplasia (BPH).
The causes of urinary retention are broad and include anatomic, neurologic, and medication-related conditions. Anatomic causes may involve the penis, urethra, or prostate and include phimosis, paraphimosis, meatal stenosis, tumors, pelvic masses, pelvic organ prolapse, foreign bodies, urethral calculi, urethritis, strictures, hematoma, vulvar edema after vaginal delivery, benign prostatic hypertrophy, prostate carcinoma, prostatitis, bladder neck contracture, and prostatic infarction. Neurologic causes include motor or paralytic disorders such as spinal shock and spinal cord syndromes, as well as sensory or paralytic disorders such as diabetes, multiple sclerosis, and other spinal cord syndromes. Medications may also precipitate retention, especially antihistamines, anticholinergics, antispasmodics, tricyclic antidepressants, alpha-adrenergic stimulators, narcotics, and NSAIDs.
Patients with acute urinary retention typically present with lower abdominal or suprapubic discomfort and may appear restless or distressed. Chronic urinary retention, in contrast, is often painless. A careful history is essential and should include any prior episodes of urinary retention, history of BPH or prostate cancer, other malignancy, prior radiation treatment, pelvic trauma, signs or symptoms of infection or abscess, symptoms suggesting urinary stones, neurologic complaints, intravenous drug use, back pain, and a complete medication review.
The physical examination should include assessment of vital signs for evidence of infection or shock, an abdominal examination, a rectal examination, and a genitourinary examination. In women, a pelvic examination should be considered. If the presentation suggests a neurologic cause, a thorough neurologic examination is necessary. In trauma patients, special attention should be given to possible urethral injury.
Because urinary retention has many possible causes, the workup is guided by the history and examination. Laboratory testing is usually limited. Renal function tests may be obtained if acute renal insufficiency is suspected, although this is uncommon in isolated acute urinary retention. A PSA test is not useful in the emergency department because it is often elevated in the setting of retention. Urinalysis may be obtained if the history or exam suggests infection. Imaging such as abdominal or pelvic ultrasound or CT may be indicated if there is concern for a mass, abscess, malignancy, bladder calculi, or another structural cause. Neuroimaging or spinal imaging is warranted if an acute neurologic process is suspected. A postvoid residual volume greater than 200 mL is generally considered abnormal.
Management begins with identifying and treating any immediately life-threatening condition. The key initial step is prompt bladder decompression. This is usually attempted with placement of a 14–18 French urinary catheter. If that cannot be passed and there is a history of prior transurethral procedures or known stricture, a smaller 10–12 French catheter may be tried. In men without prior instrumentation, a 20–22 French coudé catheter may be helpful. If catheter placement remains unsuccessful, suprapubic aspiration or suprapubic catheter placement may be required. In trauma patients with suspected urethral injury, such as those with gross hematuria, blood at the meatus, or a high-riding prostate, urethral catheterization should be deferred until a retrograde urethrogram has been performed.
After catheter placement, the bladder should be drained and urine output monitored. Rapid decompression may occasionally cause transient gross hematuria, though this is rarely clinically significant. Postobstructive diuresis is a possible complication after relief of retention, so it is reasonable to observe patients for two to three hours to ensure they do not develop hypotension or significant volume loss. If the catheter is to remain in place, a leg bag should be attached before discharge, and the patient and family should receive instructions on catheter care. Prophylactic antibiotics are not indicated for an indwelling urinary catheter unless there is evidence of infection. If BPH is the cause, starting an alpha-blocker is appropriate. Medications contributing to retention should be discontinued when possible, and constipation should be treated if present.
Common medications used for BPH-related urinary retention include alpha-blockers such as prazosin, tamsulosin, alfuzosin, and terazosin. These agents help improve urinary flow and are often started in the emergency setting when BPH is suspected.
Most patients can be discharged after successful bladder decompression, provided there is no serious underlying cause or complication. Admission is indicated for significant postobstructive diuresis requiring IV fluids or vasopressors, sepsis, retention related to spinal cord compression, obstruction caused by malignancy or a mass, or any condition requiring urgent urologic or surgical intervention.
All patients require follow-up for continued evaluation of the underlying cause, management of the catheter if one remains in place, and further treatment planning. Important pitfalls include failing to recognize a mass or malignancy, overlooking spinal cord compression, and missing a medication-related cause. A careful drug history, including over-the-counter medications, is especially important when no obvious cause is identified.
Urinary retention is the sudden or chronic inability to empty the bladder adequately. Acute urinary retention refers to the abrupt inability to void spontaneously and occurs most often in men older than 60 years. In the emergency department, the most common cause is benign prostatic hyperplasia (BPH).
The causes of urinary retention are broad and include anatomic, neurologic, and medication-related conditions. Anatomic causes may involve the penis, urethra, or prostate and include phimosis, paraphimosis, meatal stenosis, tumors, pelvic masses, pelvic organ prolapse, foreign bodies, urethral calculi, urethritis, strictures, hematoma, vulvar edema after vaginal delivery, benign prostatic hypertrophy, prostate carcinoma, prostatitis, bladder neck contracture, and prostatic infarction. Neurologic causes include motor or paralytic disorders such as spinal shock and spinal cord syndromes, as well as sensory or paralytic disorders such as diabetes, multiple sclerosis, and other spinal cord syndromes. Medications may also precipitate retention, especially antihistamines, anticholinergics, antispasmodics, tricyclic antidepressants, alpha-adrenergic stimulators, narcotics, and NSAIDs.
Patients with acute urinary retention typically present with lower abdominal or suprapubic discomfort and may appear restless or distressed. Chronic urinary retention, in contrast, is often painless. A careful history is essential and should include any prior episodes of urinary retention, history of BPH or prostate cancer, other malignancy, prior radiation treatment, pelvic trauma, signs or symptoms of infection or abscess, symptoms suggesting urinary stones, neurologic complaints, intravenous drug use, back pain, and a complete medication review.
The physical examination should include assessment of vital signs for evidence of infection or shock, an abdominal examination, a rectal examination, and a genitourinary examination. In women, a pelvic examination should be considered. If the presentation suggests a neurologic cause, a thorough neurologic examination is necessary. In trauma patients, special attention should be given to possible urethral injury.
Because urinary retention has many possible causes, the workup is guided by the history and examination. Laboratory testing is usually limited. Renal function tests may be obtained if acute renal insufficiency is suspected, although this is uncommon in isolated acute urinary retention. A PSA test is not useful in the emergency department because it is often elevated in the setting of retention. Urinalysis may be obtained if the history or exam suggests infection. Imaging such as abdominal or pelvic ultrasound or CT may be indicated if there is concern for a mass, abscess, malignancy, bladder calculi, or another structural cause. Neuroimaging or spinal imaging is warranted if an acute neurologic process is suspected. A postvoid residual volume greater than 200 mL is generally considered abnormal.
Management begins with identifying and treating any immediately life-threatening condition. The key initial step is prompt bladder decompression. This is usually attempted with placement of a 14–18 French urinary catheter. If that cannot be passed and there is a history of prior transurethral procedures or known stricture, a smaller 10–12 French catheter may be tried. In men without prior instrumentation, a 20–22 French coudé catheter may be helpful. If catheter placement remains unsuccessful, suprapubic aspiration or suprapubic catheter placement may be required. In trauma patients with suspected urethral injury, such as those with gross hematuria, blood at the meatus, or a high-riding prostate, urethral catheterization should be deferred until a retrograde urethrogram has been performed.
After catheter placement, the bladder should be drained and urine output monitored. Rapid decompression may occasionally cause transient gross hematuria, though this is rarely clinically significant. Postobstructive diuresis is a possible complication after relief of retention, so it is reasonable to observe patients for two to three hours to ensure they do not develop hypotension or significant volume loss. If the catheter is to remain in place, a leg bag should be attached before discharge, and the patient and family should receive instructions on catheter care. Prophylactic antibiotics are not indicated for an indwelling urinary catheter unless there is evidence of infection. If BPH is the cause, starting an alpha-blocker is appropriate. Medications contributing to retention should be discontinued when possible, and constipation should be treated if present.
Common medications used for BPH-related urinary retention include alpha-blockers such as prazosin, tamsulosin, alfuzosin, and terazosin. These agents help improve urinary flow and are often started in the emergency setting when BPH is suspected.
Most patients can be discharged after successful bladder decompression, provided there is no serious underlying cause or complication. Admission is indicated for significant postobstructive diuresis requiring IV fluids or vasopressors, sepsis, retention related to spinal cord compression, obstruction caused by malignancy or a mass, or any condition requiring urgent urologic or surgical intervention.
All patients require follow-up for continued evaluation of the underlying cause, management of the catheter if one remains in place, and further treatment planning. Important pitfalls include failing to recognize a mass or malignancy, overlooking spinal cord compression, and missing a medication-related cause. A careful drug history, including over-the-counter medications, is especially important when no obvious cause is identified.
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