Chapter 54. Acute Urinary Retention

Urinary retention can be either acute or chronic. The most common cause of retention is outlet obstruction secondary to benign prostatic hypertrophy in men although medication use, acute neurologic dysfunction, urinary tract bleeding or calculi, and other anatomic obstruction are also common causes in both sexes. Acute syndromes typically present with rapid onset of lower abdominal pain occasionally radiating to the lower back. Patients typically complain of difficulty voiding but some may not volunteer this information. Chronic obstruction usually presents with lower abdominal pain and the patient may note incomplete voiding or the need to void frequently.

The history should address previous episodes of obstruction, recent medication changes and over-the-counter medicine use. Assess for any history of trauma or neurologic disability or symptoms of infection. It is critical to know if any recent urologic procedures or urinary catheterizations have been performed. The duration of symptoms is also important as it is associated with the development of postobstructive diuresis and renal dysfunction.

Physical examination should address the functional and anatomic assessment of the lower urinary tract. Palpate the abdomen for a suprapubic mass corresponding to the distended urinary bladder. The penis should be examined for stricture at the meatus or palpable abnormalities of the penile urethra. The female lower urinary tract should be evaluated for bladder prolapse or stricture of the urethral meatus. In men the prostate should be assessed for size, texture, and tenderness. Perineal sensation and anal sphincter tone should be documented. A comprehensive neurologic examination should be performed.

Bedside ultrasound can be very helpful in distinguishing both the degree of obstruction and in discriminating obstruction from the sensation of fullness associated with bladder spasm in conditions like inflammatory or infectious cystitis. The patient should first be encouraged to attempt to void. After a voiding attempt the bladder is imaged with a low-frequency sector format probe in both the transverse and sagittal views (Fig. 54-1). Many manufacturers have a calculation package available to estimate the retained urine volume. Residual volumes > 50 to 150 cc are consistent with urinary retention, however, volumes are typically greater than 300 cc.

The goals of emergency department care are relieving the discomfort of retention, assessing for any secondary injury to the renal system, and treatment of the primary cause of retention.

1. Most patients with bladder outlet obstruction are in distress, and passage of a urethral catheter alleviates their pain and their urinary retention. Copious intraurethral lubrication including a topical anesthetic (2% lidocaine jelly) should be used, and a 16-French Coudé catheter is recommended if straight catheters fail. The catheter should be passed to its fullest extent to obtain free urine flow before inflating the balloon. A catheter should not be placed if there is suspicion of trauma to the urethra, either secondary to a traumatic event or recent instrumentation. The catheter should be left indwelling and connected to a leg drainage bag.

2. The patient with obstruction from hematuria represents a special case. A 3-way Foley catheter should be placed and the bladder irrigated until returning fluid is free of blood. These patients are likely to need admission for continued irrigation as the catheter often becomes blocked with clot following placement.

3. Failure to pass a urethral Foley or recent urologic procedure or instrumentation requires the involvement of a urologist for catheter placement, consultation should not be delayed. Urgent urologic consultation is also indicated for obstruction secondary to stricture, prostatitis, or urethral trauma.

4. Urine should be sent for routine analysis as well as culture. Electrolytes, BUN, and creatinine should be assessed for postobstructive renal failure. Urine output should be monitored quantitatively.

5. Oxybutynin can be prescribed for control of bladder spasms. This anticholinergic medicine can itself cause a functional obstruction. Patients may also require pain medication for control of discomfort from bladder spasms. Prescription of an α-blocker is indicated for male patients in whom BPH is the suspected etiology of their obstruction.

6. Antibiotics are not indicated unless there is also evidence of cystitis.

7. If urinary retention has been chronic, postobstructive diuresis may occur even in the presence of normal blood urea nitrogen and creatinine levels. In such patients, close monitoring of urinary output is indicated, and they should be observed for 4 to 6 hours after catheterization.

8. Precipitating causes of retention must be addressed. Offending medications should be discontinued. Infectious or neurologic causes must be completely evaluated (urgency for work-up depends on patient acuity and comorbidities).

9. In all cases of urinary retention, urologic follow-up in 3 to 7 days is indicated for a complete genitourinary evaluation. Patients should usually expect to have the catheter removed at that visit.