1 - Urinary Retention

Authors: Macfarlane, Michael T.

Title: Urology, 4th Edition

Copyright 2006 Lippincott Williams & Wilkins

> Table of Contents > Part One - Chief Presentations > Chapter 1 - Urinary Retention

Chapter 1

Urinary Retention

Acute urinary retention is the sudden inability to void. It is a common problem that usually causes agonizing suprapubic pain that demands urgent relief.

Etiology

Acute urinary retention most commonly occurs in patients who have preexisting partial bladder outlet obstruction and experience a decrease in detrusor pressures or a sudden increase in outlet resistance. Frequent precipitating events include drugs (such as -agonists, anticholinergics, antihistamines, and anesthetics), acute infection, bleeding, or overdistention of the bladder (e.g., that which happens after anesthesia).

Benign Prostatic Hyperplasia

Patients with increasing outlet resistance secondary to benign prostatic hyperplasia (BPH) may go into acute urinary retention by delaying voiding. With overdistention, the already weakened detrusor will become atonic. Edema from acute infection (e.g., prostatitis) can also send the patient into retention.

Stricture

An acute event such as infection, bleeding, or overdistention of the bladder can cause the patient with severe stricture disease to go into retention.

Blood Clots

Acute clot retention can occur secondary to bleeding from BPH or bladder tumor or be a late complication from transurethral resection of the prostate, particularly in patients on anticoagulants.

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Sloughing of a scab within the prostatic fossa can produce significant bleeding with clot formation. Prostate needle biopsy can also be a precipitating event.

Bladder Neck Contracture

A tight scar formed at the bladder neck after transurethral resection of the prostate can lead to retention if infection, bleeding, or acute overdistention of the bladder occurs.

Prostate Cancer

Acute urinary retention can occur in patients with advanced cancer of the prostate. Patients will often give a history of rapid onset of obstructive voiding symptoms as opposed to the more gradual onset usually noted with BPH.

Myopathic Bladder

Detrusor myopathy can result from overdistention of the bladder. This is most frequently seen after surgery, when the normal voiding pattern is delayed while the patient recovers from anesthesia.

Neuropathic Bladder

An areflexic neurogenic bladder will be in retention if bladder outlet resistance is higher than intravesical pressures. These patients are usually managed on intermittent catheterization.

Medications

Anticholinergic agents, antihistamines, or -agonists, all of which are common components of over-the-counter cold remedies, can cause retention in patients with mild to moderate prostatism.

Psychogenic Retention

Patients with psychogenic urinary retention have a persistent volitional override of detrusor contractility. This is not a surgical disease and should be treated with intermittent catheterization and psychiatric referral.

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Workup

The workup for acute urinary retention is primarily directed at quickly determining the underlying urologic problem (e.g., stricture, BPH, prostate cancer).

History

Inquire about strictures, venereal disease, lower urinary tract symptoms, past urologic surgery (e.g., prostate surgery), and medications. Primary anticholinergic agents, drugs with anticholinergic side effects [e.g., diphenhydramine (Benadryl), antidepressants], or -agonists [e.g., phenylephrine (Neo-Synephrine)] may precipitate urinary retention.

Physical Examination

Include a digital rectal examination (DRE) to assess the size of the prostate and careful palpation and percussion of the suprapubic area to confirm the presence of a full bladder.

Management

Initial management of the patient in retention is to provide urinary drainage by the least invasive technique available. Definitive treatment can be handled on an elective basis. It is generally recommended that more than 1,000 mL should not be drained from the bladder at once because of the possibility of a vasovagal reaction. After draining 1,000 mL, clamp the catheter for a few minutes before allowing the remainder to drain.

Lubrication

Liberal lubrication should always be used when attempting to pass any instrument into the urethra. Patients will often tightly contract their external sphincter muscles because of discomfort and anxiety. The use of 2% lidocaine (Xylocaine) jelly can make the difference between passing and not passing a catheter.

Foley Catheter

Simple placement of a Foley catheter is the treatment of choice; however, this occasionally can be a formidable task. Placement of

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a Foley in the patient with BPH can often be facilitated by using a large caliber (e.g., 22 F) catheter. The stiffness of the heavier catheter can help to separate the hypertrophied lateral lobes. Additionally, a prominent median lobe can be difficult to get over. The curve of a coud tip catheter can be effective in negotiating the median lobe of the prostate. The coud catheter is inserted with the curved tip pointing up toward the patient's head. A urethral stricture should be suspected if catheter passage is blocked in the distal or anterior urethra. Small catheters can often be used to pass a strictured area; sometimes a feeding tube as small as 8 F may be necessary.

Percutaneous Suprapubic Tube

Insertion of a percutaneous suprapubic tube requires that the bladder contain at least 200 to 300 mL; however, the fuller the better. The bladder should be easily percussed in the suprapubic region. If percussion is difficult, ultrasound can be used to confirm that the bladder is full. Previous lower abdominal surgery is a contraindication to attempting percutaneous placement because adhesions may hold a loop of bowel in the area of insertion. Other contraindications to percutaneous placement of a suprapubic tube are listed in the following section.

Contraindications to Percutaneous Suprapubic Tube

• Previous lower abdominal surgery

• A small contracted neurogenic bladder

• Coagulopathy

• Known bladder tumor

Many different prepackaged suprapubic tube kits are available, such as the Stamey catheter. Percutaneous suprapubic tubes are generally ineffective for draining patients with clot retention because of their small caliber. Open surgical placement of a large caliber tube is necessary in this case if urethral catheterization is impossible.

Filiforms and Followers

Filiforms are long, thin, fiberglass probes with straight or spiral tips that are inserted into the urethra. With careful manipulation, they can often negotiate narrow strictures and pass into the bladder. Followers are tapered stiff catheters that screw into the end of the filiform and can follow the filiform through the stricture area into the bladder. By using progressively larger caliber followers,

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the stricture area can be dilated up to allow passage of a standard Foley catheter. The stricture should be dilated to 2 F greater than the catheter that will be inserted. An open-tipped catheter can be placed over a Councill stylet and follow the filiform into the bladder. The stylet and filiform can then be removed, leaving the catheter in place. Filiforms and followers should not be used for the first time without experienced supervision. They can cause serious injury to the urethra or rectum.

Cystourethroscopy

In difficult cases, the safest and most successful technique is to pass the filiform under direct vision using a cystoscope. A flexible cystoscope can be used in the office setting or brought to the patient's bedside in the hospital or emergency room. The filiform is passed alongside the cystoscope and visually guided through the stricture. The scope is then removed and the stricture dilated with followers. Cystoscopy is also beneficial in negotiating a posterior urethral false passage created by prior attempts to insert a catheter.

Complications of Relieving Obstruction

Postobstructive Diuresis

Patients may require careful monitoring for postobstructive diuresis (>200 mL/hour) after establishing drainage, particularly if obstruction was prolonged and blood urea nitrogen (BUN) and creatinine are significantly elevated (see Chapter 29).

Hemorrhage

Relief of longstanding obstruction may result in major hematuria secondary to bladder mucosal disruption. These patients will need careful monitoring and continuous bladder irrigation. In severe cases, more rigorous measures may be necessary (see Chapter 4).

Hypotension

Significant hypotension may occur secondary to a vasovagal response or may be caused by relief of pelvic venous compression from bladder distention.