Urinary retention

Urinary retention

Urinary retention, also known as ischuria, is a lack of ability to urinate. It is a common complication of benign prostatic hyperplasia (BPH), although it can also be caused by nerve dysfunction, infection, or medications (including anticholinergics, antidepressants, COX-2 inhibitors, amphetamines and opiates). Diagnosis and/or treatment may require use of a catheter or prostatic stent.

Signs and symptoms

Urinary retention is characterised by poor urinary stream with intermittent flow, straining, a sense of incomplete voiding and hesitancy (a delay between trying to urinate and the flow actually beginning). As the bladder remains full, it may lead to incontinence, nocturia (need to urinate at night) and high frequency. Acute retention caused by complete anuria is a medical emergency, as the bladder may distend (stretch) to enormous sizes and possibly tear if not dealt with quickly. If the bladder distends enough it will begin to become painful. The increase in pressure in the bladder can also prevent urine entering from the ureters or even cause urine to pass back up the ureters and get into the kidneys, causing hydronephrosis, and possibly pyonephrosis, kidney failure and sepsis. A person should go straight to an emergency department as soon as possible if unable to urinate when having a painfully full bladder.

In the longer term, obstruction of the urinary tract may cause:

• Bladder stones
• Loss of detrusor muscle tone (atonic bladder is an extreme form)
• Hydronephrosis (congestion of the kidneys)
• Hypertrophy of detrusor muscle
• Diverticula in the bladder wall (leads to stones and infection)

Causes

In the bladder

• Detrusor sphincter dyssynergia
• Neurogenic bladder (commonly pelvic splanchic nerve damage, cauda equina syndrome, descending cortical fibers lesion, pontine micturation or storage center lesions, demyelinating diseases or Parkinson's disease)
• Iatrogenic scarring of the bladder neck (commonly from removal of indwelling catheters or cystoscopy operations)
• Damage to the bladder

In the prostate

• Benign prostatic hyperplasia
• Prostate cancer and other pelvic malignancies
• Prostatitis

Penile urethra

• Congenital urethral valves
• Phimosis or pinhole meatus
• Circumcision
• Obstruction in the urethra, for example a metastasis or a precipitated pseudogout crystal in the urine
• STD lesions (gonorrhoea causes numerous strictures, leading to a "rosary bead" appearance, whereas chlamydia usually causes a single stricture)

Other

• Paruresis ("shy bladder syndrome")- in extreme cases, urinary retention can result
• Consumption of some psychoactive substances, mainly stimulants, such as MDMA and amphetamine.
• Use of NSAIDs or drugs with anticholinergic properties.
• Stones or metastases can theoretically appear anywhere along the urinary tract, but vary in frequency depending on anatomy

Paruresis, inability to urinate in the presence of others (such as in a public restroom), may also be classified as a type of urinary retention, although it is psychological rather than biological.

Diagnostic tests

Urine flow tests may aid in establishing the type of micturition abnormality. Common findings include a slow rate of flow, intermittent flow and a large post void residual, determined by ultrasound of the bladder. A normal test result should be 20-25 mL/sec peak flow rate. A post void residual urine greater than 50 ml is a significant amount of urine and increases the potential for recurring urinary tract infections. In adults older than 60 years, 50-100 ml of residual urine may remain after each voiding because of the decreased contractility of the detrusor muscle. In chronic retention, ultrasound of the bladder may show massive increase in bladder capacity (normal capacity being 400-600 ml).

Determination of the serum prostate-specific antigen (PSA) may aid in diagnosing or ruling out prostate cancer, though this is also raised in BPH and prostatitis. A TRUS biopsy of the prostate (trans-rectal ultra-sound guided) can distinguish between these prostate conditions. Serum urea and creatinine determinations may be necessary to rule out backflow kidney damage. Cystoscopy may be needed to explore the urinary passage and rule out blockages.

In acute cases of urinary retention where associated symptoms in the lumbar spine are present such as pain, numbness (saddle anesthesia), parasthesias, decreased anal sphincter tone, or altered deep tendon reflexes, an MRI of the lumbar spine should be considered to further assess cauda equina syndrome.

Complications

Urinary retention often occurs without warning. It is basically the inability to pass urine. In some people, the disorder starts gradually but in others it may appear suddenly. Acute urinary retention is a medical emergency and requires prompt treatment. The pain can be excruciating when urine is not able to flow out. Moreover one can develop severe sweating, chest pain, anxiety and high blood pressure. Other patients may develop a shock like condition and may be require an admission to the hospital. It is not unusual for an individual to develop a heart attack after suffering acute urinary retention. Other more serious complications of untreated urinary retention include bladder damage and chronic kidney failure. Urinary retention is a disorder which is treated in a hospital and the quicker one seeks treatment, the fewer the complications.

Complications of treatment

The acute urinary retention is treated by placement of a urinary catheter (small thin flexible tube) into the bladder. This can be either a self-catheterization or a Foley catheter that is emplaced with a small inflatable bulb that holds the catheter in place. Patients can be taught to use a self catheterization technique in one simple demonstration, and that reduces the rate of infection from longer term Foley catheters. Self catheterization requires doing the procedure every 3 or 4 hours. The chronic form of urinary retention may require some type of surgical procedure. While both procedures are relatively safe, complications can occur.

In acute urinary retention, the treatment requires urgent placement of a urinary catheter (tube) into the urethra and into the bladder. These catheters are usually inserted by health care professionals. However, if the procedure is not accomplished in a sterile fashion, it can introduce bacteria into the bladder. This can result in an infection of the entire urinary tract. Therefore, sterile technique is a must when inserting a foley catheter. Careful washing of hands, meatus, and reusable catheters are also necessary with self catheterization techniques.

Sometimes the urinary catheter may cause discomfort and pain which often lasts for several days. The urinary catheter must be placed into the bladder and not near the prostate gland. Placement of the catheter near the prostate can lead to bleeding and significant irritation. In most patients with benign prostate hyperplasia (BPH), a procedure known as transurethral resection of the prostate (TURP) is performed to relieve bladder obstruction. The surgery is done with a small lighted instrument which is inserted into the urethra under anesthesia. The surgeon can core out the enlarged prostate and relieve obstruction. However, the procedure does have risks. There are risks of anesthesia which may include allergy to medications or low blood pressure which results from spinal anesthesia.

The surgical complications from TURP include a bladder infection, bleeding from the prostate, scar formation, inability to hold urine and inability to have an erection. The majority of these complications are short lived and most individuals recover fully within 6–12 months. Some people with BPH are treated with medications like finasteride or dutasteride to decrease prostate enlargement. The drugs only work for mild cases of BPH but also have mild side effects. Some of the medications decrease libido and may cause dizziness, fatigue and lightheadedness. Unfortunately, medications only work in less than 5 percent of individuals with BPH.

Incidence and prevalence

Urinary retention is a common disorder in elderly males. The most common cause of urinary retention is benign prostate hypertrophy and this disorder starts around age 50 and symptoms may appear after 10–15 years. BPH is a progressive disorder and narrows the neck of the bladder leading to urinary retention. By the age of 70, almost 10 percent of males have some degree of BPH and 33% have it by the eighth decade of life. While BPH rarely causes sudden urinary retention, the condition can become acute in the presence of certain medications (blood pressure pills, anti histamines, antiparkinson medications), after spinal anaesthesia or stroke.

In young males, the most common cause of urinary retention is infection of the prostate (known as "acute prostatitis"). The infection is acquired during sexual intercourse and presents with low back pain, penile discharge, low grade fever and an inability to pass urine. The exact numbers of individuals with acute prostatitis is unknown because many do not always seek treatment. In the USA, at least 1-3 percent of males under the age of 40 develop urinary difficulty as a result of acute prostatitis. Most physicians and other health care professionals are aware of these disorders. Worldwide, both BPH and acute prostatitis have been found to occur in males of all races, color and ethnic backgrounds. Cancers of the urinary tract can cause urinary obstruction but the process is more gradual. Bladder cancer, prostate or ureters can gradually obstruct urine output. Cancers often present with blood in the urine, weight loss, lower back pain or gradual distension in the flanks.

Treatment

In acute urinary retention, urinary catheterization, placement of a prostatic stent or suprapubic cystostomy relieves the retention. In the longer term, treatment depends on the cause. Benign prostatic hypertrophy may respond to alpha blocker and 5-alpha-reductase inhibitor therapy, or surgically with prostatectomy or transurethral resection of the prostate (TURP). Older patients with ongoing problems may require continued intermittent self catheterization. 5-alpha-reductase inhibitor increase the chance of normal urination following catheter removal.

See also

• Constipation, inability to defecate
• Urinary incontinence, inability to hold the urine