ACUTE URINARY RETENTION:
A painfull inability to void urine in the presence of a palpable bladder
Causes:
Acute urinary retention often appears suddenly in patients with longstanding symptoms of
bladder outflow obstruction, for example benign prostatic hypertrophy, bladder neck
hypertrophy, or prostatic carcinoma.
Other causes include - as a complication of surgery, due to fluid overload, drugs, pain,
anxiety, embarrassment or the supine posture.
Less common causes include:
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stones or blood clots in the urethra
urethral stricture
constipation
pregnancy - particularly associated with a retroverted uterus
pelvic tumour
genital herpes - painful ulceration may result in urinary retention
Medications: anticholenergic, psudoephidrine (cold medications)
Clinical Features:
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the patient reports a sudden, painful inability to pass urine
there is usually a longer history of bladder outflow symptoms
suprapubic pain which typically, comes in spasms
patient is acutely distressed
pain worsens with time
bladder is enlarged and tender
the patient is typically male
Acute retention may also be acute on chronic, that is, chronic obstruction which suddenly
becomes acute, being precipitated by overfilling, urinary tract infection or severe constipation.
History and examination - classically the patient is anuric, in great discomfort and has an
intense desire to micturate. The bladder is palpable and there is suprapubic dullness to
percussion.
Passing a urethral catheter releases a large volume of urine - more than 500 ml in an adult which confirms the clinical diagnosis. Passing a catheter helps to exclude renal failure as a
cause of anuria.
If patient unable to void, must decide whether this is due to outflow obstruction, or
decreased urine production.
Investigations:
The diagnosis is confirmed by catheterisation.
Additional investigations should be performed to ascertain the cause:
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urinalysis - blood, infection
blood - white cell count, haemoglobin, urea and electrolytes
abdominal radiology might be performed to look for bladder calculi
A rectal examination should also be done to assess the size of the prostate and to exclude
constipation.
Management:
The first objective is to relieve the patient of the discomfort so provide some strong opiate
analgesia. Try conservative methods first - privacy, sound of running water, and making the
patient stand up.
Catheterise if these conservative methods do not provide relief. First, try a Foley catheter
inserted via the urethra; if unsuccessful, try a suprapubic catheter.
Some factors that should discourage an attempt at simple urethral catherisation include:
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previous prostatectomy
known urethral stricture
history of difficult catheterisation
non-retractile foreskin
Contraindications for suprapubic catheter:
 Previous Bladder Ca
 Non palpable bladder
 Un diagnosed haematuria
 Previous pelvic or abdominal surgery
 Coagulopathy
CHRONIC RETENTION
Chronic urinary retention involves chronic incomplete bladder emptying. The patient is
generally asymptomatic. An enlarged bladder may be found on abdominal examination.
Causes include:
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prostatic enlargement, the most common cause
abnormalities of structure and function of bladder muscle or sphincter mechanism
persistent urethral obstruction
Clinical features include:
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asymptomatic
nocturnal enuresis
enlarged bladder
voiding is usually by overflow when the bladder becomes full - i.e. maximally
distended.
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features are those of bladder outflow obstruction, ie frequency, nocturia, urgency and
urge incontinence, hesitancy, terminal dribbling and poor stream
Complications include:
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those of prolonged bladder outflow obstruction: - hypertrophy of bladder muscle bladder diverticula formation - hydronephrosis may occur, and may lead to renal
failure
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acute on chronic urinary retention - precipitated by factors such as: - constipation urinary tract infection - overfilling - drugs, for example, antidepressants or diuretics
If the patient presents with uncomplicated chronic urinary retention, management is as
follows:
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do not catheterise
investigate renal function - creatinine and haemoglobin; excretory and endocrine
function respectively
catheterisation is indicated in:
o acute on chronic retention
o a patient who is ill, managing a medical emergency. Note that this may correct
an underlying hyperkalaemia, but it is important to monitor the because there
is a subsequent diuresis
o the patient who already has a urinary tract infection
Medical management should probably be confined to patients with symptoms but no other
pathology. Pharmacological options include:
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alpha blockers
5 alpha reductase inhibitors