Chapter 92: Acute Urinary Retention

Acute urinary retention is a common painful urologic emergency characterized by a sudden inability to pass urine, with lower abdominal distention or pain. Most patients with urinary retention are elderly men with benign prostatic hyperplasia.^1,2 The incidence and risk increase with age. There is a 20% recurrence within 6 months after an episode of urinary retention.² Few data are available for women. In men with spontaneous urinary retention, the mortality rate at 1 year increases from 4.1% in patients age 45 to 54 years to 32.8% in those age 85 years and older.³

The voiding process, or micturition, involves the complex integration and coordination of high cortical neurologic (sympathetic, parasympathetic, and somatic) and muscular (detrusor and sphincter smooth muscle) functions. As the sensory impulse of bladder distention transmits to cortical centers, these areas of the brain smoothly coordinate voluntary urination. Continent urine storage in the bladder requires both relaxation of the detrusor muscle (through β-adrenergic stimulation and parasympathetic inhibition) and contraction of the bladder neck and internal sphincter (through α-adrenergic stimulation). The contraction of bladder detrusor muscle (by cholinergic muscarinic receptors) and relaxation of both the internal sphincter of bladder neck and the urethral sphincter (through α-adrenergic inhibition) contribute to smooth urination.⁶

Any causes that interfere with the neurologic control of the voiding process can result in voiding dysfunction. Urinary retention is the inability to void voluntarily despite a distended bladder and results from the dysfunction of the detrusor muscle and its coordination with the control of the bladder outlet. As bladder outlet obstruction progressively increases, the urine stream decreases in strength and size despite forceful and prolonged detrusor contraction. In chronic decompensation of urination, diminished detrusor muscle contractility is more pronounced, with a large amount of residual urine volume, compared to acute decompensation.

The causes of urinary retention (Tables 92-1, 92-2 and 92-3) are categorized into several domains: obstructive, neurogenic, traumatic, infectious, operative, psychogenic, childhood, extraurinary, and pharmacologic.^4,5,6,7 A detailed history of the present illness and physical examination, especially the neurologic examination, supported by imaging and urodynamic studies, reveal the cause in the majority of patients.

The most common presentation is an elderly male with inability to void for several hours and lower abdominal distention or pain, secondary to benign prostatic hyperplasia.

Collect past medical history to look for a history of prostatism, prostate or urinary bladder cancer, bladder calculi, indwelling urethral catheter or injury to urethra, prostate surgery, or pelvic radiation therapy. Ask about history of urinary urgency, frequency, or hesitancy; decreased force and caliber of stream; terminal dribbling; nocturia; and incontinence (typically due to overflow phenomena). Gross hematuria may indicate infection, bladder calculi, or urinary tract neoplasm. A patient with urethral stricture may have a history of Foley catheter insertion, cystoscopy, trauma, or previous radiation therapy or infection. Collect any history of new medications, including common cold preparations, anticholinergics (including bronchodilators), sympathomimetic agents, and psychogenic and other potential agents (Table 92-3). Obtain a detailed neurologic history, looking for a causative lesion from high cortical function down to peripheral nerves that determine end-organ function. Identify possible spinal cord injury by determining recent activities including any remote trauma.

Fever, tachycardia, tachypnea, and hypotension suggest infection or sepsis. Hypertension or tachycardia may be transient and may resolve after bladder decompression. Consider urinary retention in patients complaining of lower abdominal pain, even if they do not offer urinary complaints. On abdominal examination, palpitate or percuss from the epigastric area to the lower abdomen to identify a painful mass (distended bladder) in the lean patient. Examine the external genitalia to identify phimosis, paraphimosis, meatal stenosis or stricture, or evidence of urethral or penile trauma.

Perform digital rectal examination (either before or after relief of obstruction, depending on patient comfort) to evaluate the anal-rectal area and prostate, assessing anal tone, perineal sensation, prostate enlargement, stool impaction, and any possibility of malignancy. A nodular or rock-hard prostate may suggest prostate cancer, which must be confirmed at a later date. Women with urinary retention should receive a pelvic examination to detect possible inflammatory lesions or pelvic or adnexal masses. Perform a neurologic examination to determine any neurogenic cause. After successful drainage of the distended bladder, a repeat physical examination of the lower abdomen is indicated to help exclude an unresolved extraurinary bladder problem (e.g., appendicitis) needing further management.

Bedside US can easily identify urinary retention. However, the need for further diagnostic tests will depend on the nature of the clinical presentation, precipitating factors, and the patient's comorbidities. Obtain a urine culture to identify urinary tract infection. Hematuria secondary to the physical trauma of catheter insertion that clears over time is common (see chapter 91, "Urinary Tract Infections and Hematuria"). A CBC should be checked for patients with suspected severe infection, massive hematuria with possible hypovolemia, or hematologic diseases. Prolonged obstruction may result in impaired renal function and electrolyte imbalance, so obtain renal function studies and serum electrolytes. Formal abdominal US or CT may be indicated to identify pelvic or abdominal masses, bladder stones, or hydronephrosis, but are not routinely needed if symptoms resolve after catheter placement. Neuroimaging or spinal imaging is needed if examination identifies neurologic deficits. Cystourethrography may be required eventually to evaluate the pathology in the lower urinary tract; however, this is not an ED procedure.

The goal of ED management is outlined in Table 92-4. Bladder decompression is by urethral or suprapubic catheterization. Difficult catheterization in males can result from urethral stricture, prostatic enlargement, or postsurgical bladder neck contractures. If the patient recently underwent urologic surgery (e.g., radical prostatectomy or complex urethral reconstruction), consult the urologist before attempts at catheter placement.

URETHRAL CATHETERIZATION TECHNIQUE

Most catheters are made of latex, but silicone catheters are available for patients with latex allergy. The retrograde injection of 10 to 15 mL of water-soluble anesthetic lubricant (e.g., 2% lidocaine jelly) 5 to 10 minutes before inserting the catheter can alleviate patient discomfort (Figure 92-1). Retract the foreskin when inserting the catheter, and remember to reduce the foreskin once the catheter is in place. The catheter is in place when urine is freely draining. Do not inflate the retention balloon until urine begins to flow through the catheter into the clear extension tube. The urethra can be injured from inflation of the retention balloon within the urethra. If the catheter balloon is inflated in the prostatic urethra and not the bladder, urine may or may not drain freely, and balloon inflation causes extreme pain⁸ (Figure 92-2). Forceful attempts at catheter removal with the balloon still inflated can cause edema and tears to the urethra.

If attempts at passage of a straight 14- to 18-French Foley catheter fail, use a firm angulated coudé catheter, positioned so the tip points anteriorly. The curved tip adjusts to the course of the prostatic urethra. A modification of the standard catheterization technique was reported in a small convenience sample, using US guidance while applying transrectal pressure to help smooth out the course of the prostatic urethra and simultaneously gently advancing the catheter.⁹ Applying this technique requires two healthcare providers—one using US and applying rectal pressure, and another advancing the catheter.

During insertion, a false lumen can be created, or the catheter may kink in the urethra, especially in patients with underlying urethral strictures or prostate enlargement. Consult urology for management. If catheterization produces gross blood, deflate the balloon, remove the catheter, and do not attempt reinsertion because a false passage (through the penile soft tissue instead of the urethra) may have been produced. Management may require urology consultation for the use of a guidewire, flexible filiforms, and dilation followers for progressive dilation of the urethra to place a catheter.

SUPRAPUBIC CATHETERIZATION TECHNIQUE

Suprapubic catheterization can be performed in patients after failure of several attempts of urethral catheterization and as long as there is no obvious pelvic trauma or abnormal anatomy in the lower abdomen. This may be the only option to decompress an extremely painful, distended bladder when urethral catheterization is not possible. US-guided suprapubic catheterization has a low complication rate.¹⁰ Prepare the suprapubic area with betadine and local anesthesia. Visualize the distended bladder with US. While monitoring with US, advance a 22-gauge spinal needle with 10-mL syringe posteriorly and caudally at a 30-degree angle from the true vertical and 60 degrees from the horizontal plane of the abdomen, 3 to 4 cm above the pubic symphysis in the midline. Advance the needle while withdrawing on the syringe. US visualization of the needle in the bladder and urine return indicates correct placement. Use the depth and position of this attempt to direct the placement of the obturator. Make a small skin incision in the midline at the point of prior needle removal. The cystostomy catheter and obturator assembly are then placed in similar manner as the spinal needle, again aspirating for urine (Figures 92-3 and 92-4).

After inflating the retention balloon, withdraw the obturator and leave the catheter in the bladder. Secure the catheter with a suture. If a guidewire is used for catheter insertion, remove the pull-apart sheath after successful bladder placement.

Patients with long-standing obstruction are at risk for postobstructive diuresis and postobstructive renal failure. Monitor for 4 hours minimum for significant hourly urinary output (>200 mL/h over input) after initial return. If this degree of output continues, admit the patient with volume replacement adjusted hourly according to urine output. Patients with significant elevations of BUN or creatinine should be admitted. Patients should be reassessed after Foley insertion for resolution of symptoms.

Routine use of antibiotics for the prevention of bacteriuria or for the treatment of asymptomatic bacteriuria is not suggested. Antibiotics are reserved for symptomatic urinary tract infection⁴ (see chapter 95, "Complications of Urologic Procedures and Devices").

Pharmacologic therapy with an α-adrenergic receptor blocker, which exerts its effects on the bladder neck and prostate, may relax bladder smooth muscle, reducing outlet resistance to urinary flow (Table 92-4). α-Adrenergic blockers such as alfuzosin, 10 milligrams daily, or tamsulosin, 0.4 milligram daily, increase the success of spontaneous voiding after the catheter is removed.¹¹ Warn patients, especially the elderly, about possible postural hypotension. α-Adrenergic blockers may also shorten the interval of time before a successful voiding trial and prevent recurrent episodes.¹²

The majority of patients with urinary retention are discharged home with a catheter connected to a leg bag and wait for further surgical intervention after the urology clinic visit. Patients should be educated in Foley catheter care and bag drainage and given a list of alarm symptoms that should prompt return to the ED. These include fever, return of symptoms, repeated vomiting, abdominal pain, catheter blockage, or penile pain. Penile pain suggests migration of the balloon into the proximal urethra. Feelings of urgency or bladder spasm can be treated with oxybutynin, 2.5 milligrams PO two or three times a day. Oxybutynin has anticholinergic properties and can cause the same adverse effects as any anticholinergic agent. There is no satisfactory treatment for urinary leakage around the catheter. Placement of a larger catheter is not typically effective.

α-Adrenergic blockers can be prescribed as needed (Table 92-4). Recommend urology follow-up within 3 to 7 days. A longer period of Foley drainage is encouraged in patients with retention volumes >1.3 L to improve chances of successful voiding. The serum prostate-specific antigen assay and long-term use of a 5α-reductase inhibitor could be evaluated at urology follow-up.

For precipitated urinary retention, remove the catheter in the ED and allow a voiding trial. Discontinue offending medications. Patients with clot retention, hematuria and coagulopathy, sepsis, possible neurologic cause of urinary retention, or other significant comorbidities should be admitted.¹²

FEMALES WITH URINARY RETENTION

Urinary retention in women is uncommon. The obstructive causes of urinary retention in women are usually related to gynecologic problems (Table 93-1), but neurogenic causes can develop in both men and women.¹³

The management of urinary retention in females involves catheterization and attending to any treatable cause. The ideal selection of catheterization method, including in and out catheterization, short-term indwelling urethral catheter followed by a trial of voiding, or clean intermittent self-catheterization, depends on the clinical assessment of precipitating factors and underlying conditions. α-Adrenergic blockers do not appear to be helpful in women with urinary retention. If there is no apparent cause, refer to a gynecologic urologist for urodynamic studies.¹³

GROSS HEMATURIA AND CLOT RETENTION

Gross hematuria can lead to clot retention, resulting in pain and hypertension and tachycardia from acute bladder distention. Management of gross hematuria is placement of a 20- to 24-French triple-lumen catheter (one port for urine drainage, one port for balloon inflation, one port for bladder irrigation) and irrigation with saline until clear to evacuate clots.¹⁴ Patients with clot retention may require admission, because clot retention may reoccur and may require cystoscopic clot removal. Patients with gross hematuria from coagulopathy (i.e., warfarin) should have clotting parameters corrected as appropriate and be admitted.

POSTOPERATIVE URINARY RETENTION

Treatment is discussed in chapter 87, "Complications of General Surgical Procedures." For patients with retention after GU or pelvic procedures, consult with the operating surgeon. Otherwise, for patients with normal renal function and no obstruction, bladder catheterization to relieve symptoms and then removal of the catheter and a trial of voiding are usually all that is necessary.