- Email: [email protected]
The patient with urinary retention
URINARY RETENTION
The patient with urinary retention
the patient should be given 100% oxygen by an anaesthetic mask. Data on the optimal induction agent are limited, but ketamine (a parenteral anaesthetic agent) and inhalational anaesthetics (e.g. isoflurane, halothane) have been used and have broncho-dilating properties. Their use requires specialist expertise, because they have vasodilating and myocardial depressant actions and may sensitize the myocardium to catecholamines. The potential for induction of life-threatening arrhythmias and/or hypotension is high. Following intubation, use of a benzodiazapine is indicated to ensure sedation, with neuromuscular blockade to improve pulmonary compliance and aid ventilation. A ventilation strategy of controlled hypoventilation (permissive hypercapnoea) with high FiO2 is commonly used. Often, only a short period of ventilation and ICU care is required, because most patients respond rapidly to these and previously started treatments. However, positivepressure ventilation in patients with asthma has specific problems including hypotension, barotrauma (pneumothorax and pneumomediastinum) and nosocomial infection. The most common cause of severe hypotension in a ventilated asthmatic patient is autopositive end-expiratory pressure secondary to air trapping. This can be corrected by stopping ventilation for a brief period (< 60 seconds) while observing the patient’s oxygen status, then restarting at a ventilation rate of 8–10 per minute.
Rebecca Hamm Mark J Speakman
Urinary retention can be acute, chronic or acute-on-chronic. The most common presentation is a patient in acute urinary retention (AUR) complaining of pain associated with the desire, but the inability to void. In AUR, the volume drained is usually less than 1 litre. If the volume drained is 1 litre or more, this can be used as a distinction between acute and acute-on-chronic retention, particularly if associated with less pain (a finding that is more typical of chronic urinary retention (CUR)). CUR occurs when patients retain a substantial amount of urine in the bladder after each void. However, a defined volume for CUR is more difficult. and the finding of persistent residual volumes of >300 ml (some authors suggest >500 ml) after voiding is often used as evidence of chronic retention, although some patients present with many litres in their bladders. Generally, AUR is painful whilst CUR is not. Although it is usually stated that patients with AUR did not have previous lower urinary tract symptoms (LUTS), it is more likely that many of these patients had not complained of these symptoms before. That is, they may have either not recognized their significance or assumed them to be an inevitable consequence of ageing.
Discharge and follow-up Before discharge, check that the patient’s inhaler technique is adequate, that all medications (inhalers, corticosteroid, antibiotics) have been altered appropriately, and that he or she has and understands a PEF record chart and symptom-based asthma plan. The GP must be informed directly whenever a patient with asthma has needed A&E or hospital treatment following an exacerbation. The patient should be reviewed by an asthma liaison nurse or GP within 48 hours of discharge, and in a specialist hospital clinic after about 1 month.
Aetiology AUR occurs in an obstructed or decompensated lower urinary tract and may be precipitated by the combination of a large fluid intake volume and some delay in micturition resulting in bladder overdistension and consequent reduced bladder contractility. Common causes of retention include constipation, urinary infection, drugs with an anticholinergic or sympathomimetic effect and clot retention. Underlying causes are shown in Figure 1. The aetiology of CUR is more complex and can be divided into high-pressure chronic retention (HPCR) and low-pressure chronic retention (LPCR). The terms ‘high’ and ‘low’ refer to the detrusor pressure at the end of micturition, i.e. at the start of the next filling phase. Bladder outlet obstruction usually exists in high-pressure chronic retention and the voiding detrusor pressure is high, but
FURTHER READING British Thoracic Society, Scottish Intercollegiate Guidelines Network. British guideline on asthma management: a national clinical guideline. Thorax 2003; 58: (Suppl. 1): i1–94. (Essential reading for all clinicians involved in the care of asthma patients.) Cates C J, Rowe B H, Bara A. Holding chambers vs nebulisers for beta-agonist treatment of acute severe asthma. The Cochrane Library 2001; 3. Parameswaran K, Belda J, Rowe B H. Addition of intravenous aminophylline to beta2 agonists in adults with acute asthma. The Cochrane Library 2001; 3. Rowe B H, Bretzlaff J A, Bourdon C et al. Magnesium sulphate for treating exacerbations of acute asthma in the emergency department. The Cochrane Library 2001; 2.
THE FOUNDATION YEARS 1:3
Rebecca Hamm is a Specialist Registrar in urology on the South-West rotation, UK, and is currently working at Taunton and Somerset Hospital, Taunton, UK. Mark J Speakman is a Consultant Urologist and Associate Medical Director at the Taunton and Somerset Hospital, UK. He qualified from Charing Cross Hospital, London, and trained in urology in Oxford and Glasgow. His research interests include benign and malignant prostate disease and bladder function.
25
© 2005 The Medicine Publishing Company Ltd
URINARY RETENTION
α-adrenergic activity: some cases of AUR are associated with a rise in the prostatic intraurethral pressure through an increase in α-adrenergic stimulation (e.g. stress, cold weather, sympathomimetic agents used in cold remedies). Prostatic infarction or prostatitis may contribute to this process. Bladder overdistension also leads to increased adrenergic tone.
Aetiology of urinary retention Obstructive • Mechanical obstruction (e.g. benign prostatic hyperplasia (BPH), urethral stricture) • Dynamic obstruction i.e. increase in smooth muscle tone (e.g. postoperative pain, drugs) Neurological • Interruption of sensory or motor innervation to the bladder (e.g. pelvic surgery, multiple sclerosis, spinal injury, diabetes, psychogenic) Myogenic • Over-distension of the bladder (e.g . post-anaesthesia, high alcohol intake)
A decrease in the stromal:epithelial ratio has been noted in AUR. This may in part explain the effect of the agent finasteride, which is known to act mainly on the epithelial component of the prostate and has been reported to reduce the risk of retention. Neurotransmitter modulation: reduction of non-adrenergic, noncholinergic transmitters (e.g. vasoactive polypeptide (VIP), neuropeptide Y (NPY)), has been postulated as an underlying cause.
1
Presentation
associated with poor urinary flow rates. The constantly raised bladder pressure during both the storage and voiding phases of micturition creates a back pressure on the upper tract drainage and results in bilateral hydronephrosis. Other patients may have large-volume retention in a very compliant bladder with no hydronephrosis or renal failure and these are said to have LPCR. Urodynamic studies in these patients show low detrusor pressures, low flow rates and very large residual volumes. LUTS, however, are usually minimal in CUR, certainly in the early stages, until the onset of nocturnal enuresis, which results from the drop in urethral resistance during sleep, which is overcome by the maintained high bladder pressure causing incontinence – sometimes inappropriately called overflow incontinence.
In acute retention, patients present with lower abdominal discomfort and swelling, an inability to pass urine (or passing only small amounts of urine), and with a palpable mass arising from the pelvis which is dull to percussion. Examination should include a digital rectal examination noting the size and texture of prostate, anal tone and the presence or absence of constipation. Although AUR is primarily a clinical diagnosis, a bladder volume scan (if available) will further confirm the diagnosis before catheterization. Dipstix test of the urine should always be performed and a catheter specimen of urine (CSU) sent if there are signs of infection: urinary infection should be treated. Urea and electrolytes should be checked in all patients with urinary retention. Renal ultrasound is indicated in patients with high-volume retention and in patients with abnormal renal function. Prostate-specific antigen (PSA) testing is best avoided during the acute episode, since any instrumentation of the prostate leads to a spurious rise in PSA.
Epidemiology Community-based studies suggest that 10% of men in their 70s experienced AUR over a 5-year period, and the risk increases to one in three over 10 years. AUR is rare in younger men; men in their 70s are five times more at risk of AUR than men in their fourth decade. It can be calculated that a 60-year-old man would have a 23% probability of experiencing AUR if he were to reach the age of 80. Retention is over ten times more common in men than in women. An underlying neurological cause should always be considered in women. The most common underlying causes in women are infection or inflammation occurring post-partum, or secondary to herpes, Bartholin’s abscess, acute urethritis or vulvovaginitis. AUR is rare in children and is usually associated with infection or occurring postoperatively.
Differential diagnosis This is not usually difficult, but diverticulitis or a diverticular abscess, perforated or ischaemic bowel or an abdominal aortic aneurysm are all recognized as potentially more serious conditions that can be referred into hospital as ‘acute retention’. Urinary retention may occur secondary to any of the above conditions and it is therefore important that the patient is re-examined soon after catheterization to confirm that the symptoms and signs have resolved. Occasionally an obese patient with renal failure may be mistaken for a case of AUR.
Management of AUR (Figure 2) Pathology and pathogenesis
Treatment of acute retention requires urgent catheterization. Whether patients are catheterized at home by a GP, in accident and emergency departments or in surgical/urology wards depends mainly on local circumstances, as does the decision to admit or send home after catheterization. If patients are kept in hospital awaiting definitive treatment, this results in overall longer total hospital stay. The urine volume drained in the first 10–15 minutes following catheterization must be accurately recorded in the patient’s notes, to enable a distinction between acute and acute-on-chronic reten-
Four factors have been implicated in pathogenesis: Prostatic infarction: prostatic infarction caused by infection, instrumentation, and thrombosis, is far more common in prostatectomy specimens after AUR than in cases of clinical benign prostatic hyperplasia alone. This may lead to neurogenic disturbance, preventing relaxation of the prostatic urethra, or to swelling and a rise in urethral pressure.
THE FOUNDATION YEARS 1:3
26
© 2005 The Medicine Publishing Company Ltd
URINARY RETENTION
Management of chronic urinary retention
Management of acute urinary retention after catheterization
Normal renal function
No
Chronic retention
Monitor fluid balance Check renal function daily Elective TURP if fit Long-term catheter if not
Abnormal renal function or upper tract dilatation No
Yes
Symptomatic or complications
Catheter drainage monitor diuresis TURP if fit or LTC or CISC
Yes
Prostate feels benign
No
Further investigation for prostate cancer
No
Teach catheter care and use of flip flow valve/leg bag discharge with date for TURP
Yes
Retention <1 litre/no history of LUTs/obvious precipitating cause
Yes
Commence α-blocker, laxatives/antibiotics TWOC at 48 hours
No
Yes
Regular follow-up of symptoms and creatinine
Urodynamic investigation Good detrusor function Yes
Yes
Successful TWOC
No
Teach catheter care and use of flip flow valve/leg bag dishcharge with date for TURP
TURP if fit or LTC or CISC
LTC or CISC
3
prior to the episode of retention) • loss of the corticomedullary concentration gradient caused by reduced urinary flow through the chronically obstructed kidney • an osmotic diuresis caused by the high urea level. In about 10% of cases this is excessive and requires careful fluid replacement. Daily weighing is an accurate way of monitoring fluid output. After the first 24 hours, fluid replacement should not religiously follow the output, which would perpetuate the diuresis. Potassium levels, which are often high, should be monitored and will usually (but not always) fall with the diuresis. Catheterization is often followed by haematuria; this is caused by renal tract decompression and not usually by the catheter itself. The practice of slow decompression is unnecessary and haematuria usually settles after 48–72 hours. If there is evidence of renal failure, which settles with catheterization, the patient should not undergo a TWOC before a definitive procedure has been considered. If presenting electively through outpatients, the indications for catheterization before TURP in cases of CUR are again renal impairment and water and salt retention; otherwise it is best to avoid catheterization to avoid infection and bladder shrinkage before TURP, but the patients should be listed for early surgery. Patients with low-pressure chronic retention do poorly after TURP, frequently failing to void after surgery even after prolonged periods of catheteritization. A number of interesting debates remain in the management of patients with retention, as follows.
Yes
Discharge on α blocker/finasteride. Review in outpatients with flow rate and residual volume estimation TURP: Transurethral resection of the prostate TWOC: Trial without catheter 2
tion. Less than 800 ml, particularly if associated with a known predisposing factor, is associated with a higher chance of a successful trial without catheter. AUR was previously considered an absolute indication for transurethral resection of the prostate (TURP). However, more recently, other treatments have been considered. AUR is the indication for prostatectomy in 25% of patients in the USA and up to 50% of patients in the UK. A trial without catheter (TWOC) is now considered in most patients. In the UK National Prostatectomy Audit, AUR and CUR accounted for 28% and 26% of the indications for TURP respectively.
Management of CUR (Figure 3) The management of CUR is more complex. Catheterization is less urgent as the condition is generally less painful. Early catheterization is indicated if there is renal dysfunction or upper tract dilatation. Patients must be monitored for a post-obstructive diuresis. They can pass many litres of urine in the first few days following catheterization. The diuresis is due to: • off-loading of retained salt and water (retained in the weeks
THE FOUNDATION YEARS 1:3
No
Urethral versus suprapubic catheterization The principal advantages of suprapubic catheterization are reduction in urinary tract infections (UTIs), less stricture formation and 27
© 2005 The Medicine Publishing Company Ltd
URINARY RETENTION
the fact that it permits TWOC without catheter removal. It could therefore be regarded as the preferred route of catheterization. Disadvantages are that it is a more complex procedure, which not all health professionals are adequately skilled to perform, and also has the potential for serious complications, such as bowel perforation and peritonitis, particularly where there has been previous pelvic surgery. Therefore, it is usually reserved for cases where urethral catheterization has failed, and in some cases of chronic retention where intermittent self-catheterization is not an option and long-term catheterization may be necessary. Urine should always have been withdrawn using an exploratory ‘tap’ with a small needle before trocar and cannula insertion.
Prevention Community-based studies and the placebo arms of long-term randomized studies have identified predictive risk factors for AUR. Risk factors include men >70 years of age with LUTS, an International Prostate Symptom Score (IPSS) >7 (i.e. moderate or severe LUTS), a flow rate of <12 ml/second and/or a prostate volume of >40 cm2 or a PSA >1.4 ng/ml, which is a good proxy for prostate volume. Studies have suggested that hesitancy may also predict a greater risk of subsequent AUR. Placebo-controlled trials have shown that treatment with finasteride for periods >6 months reduces the risk of AUR by over 50%. Long-term use of α-adrenergic receptor antagonists (e.g. alfuzosin, tamsulosin) may reduce the rate of AUR by a similar extent.
TWOC If a policy of TWOC was carried out in all patients with AUR, then about 20% of patients would be expected to have a successful trial and avoid surgery in the long term. With these statistics, it may not be advisable to trial all patients. Factors leading to a high probability of successful TWOC include: • UTI with no previous obstructive symptoms • gross constipation • recently started anticholinergic or sympathomimetic drugs • drained volume <500 ml. Conversely, factors leading to a high probability of unsuccessful TWOC include: • patients >75 years of age • drained volume >1 litre • previous LUTS • voiding detrusor contraction (on urodynamics) of < 35 cmH2O. The duration of catheterization before TWOC alters the chance of a successful trial of catheter removal. In one study, 44% of patients had a successful TWOC after a single day of catheterization, 51% were successful after 2 days of catheterization and 62% after 7 days of catheterization. Higher success rates for TWOC have been reported after treatment with the α-blockers alfuzosin and tamsulosin. These drugs are started on admission and TWOC carried out after 48 hours. Initial success rates increase from 30% to 50% with these drugs. However, if an initial TWOC is successful, over half of these men will experience recurrent AUR over the next year. The role of clean intermittent self-catheterization (CISC) CISC is an alternative to an indwelling catheter. It is a safe, simple and well accepted technique that results in fewer UTIs than indwelling catheterization. There are no external devices and maintenance of sexual activity is possible. It may also increase the rate of successful spontaneous voiding. CISC can be used either instead of an indwelling catheter after an episode of acute or CUR or in patients who fail to void following a prostatectomy (who go into retention secondary to detrusor failure following TURP). Prostatectomy after retention Prostatectomy after AUR is associated with an increased morbidity due to infection, perioperative bleeding and increased transfusion rates as well as up to a threefold increase in mortality. In addition, a higher percentage of men fail to void after TURP compared with men undergoing surgery for symptoms alone.
THE FOUNDATION YEARS 1:3
28
© 2005 The Medicine Publishing Company Ltd
The patient with urinary retention
the patient should be given 100% oxygen by an anaesthetic mask. Data on the optimal induction agent are limited, but ketamine (a parenteral anaesthetic agent) and inhalational anaesthetics (e.g. isoflurane, halothane) have been used and have broncho-dilating properties. Their use requires specialist expertise, because they have vasodilating and myocardial depressant actions and may sensitize the myocardium to catecholamines. The potential for induction of life-threatening arrhythmias and/or hypotension is high. Following intubation, use of a benzodiazapine is indicated to ensure sedation, with neuromuscular blockade to improve pulmonary compliance and aid ventilation. A ventilation strategy of controlled hypoventilation (permissive hypercapnoea) with high FiO2 is commonly used. Often, only a short period of ventilation and ICU care is required, because most patients respond rapidly to these and previously started treatments. However, positivepressure ventilation in patients with asthma has specific problems including hypotension, barotrauma (pneumothorax and pneumomediastinum) and nosocomial infection. The most common cause of severe hypotension in a ventilated asthmatic patient is autopositive end-expiratory pressure secondary to air trapping. This can be corrected by stopping ventilation for a brief period (< 60 seconds) while observing the patient’s oxygen status, then restarting at a ventilation rate of 8–10 per minute.
Rebecca Hamm Mark J Speakman
Urinary retention can be acute, chronic or acute-on-chronic. The most common presentation is a patient in acute urinary retention (AUR) complaining of pain associated with the desire, but the inability to void. In AUR, the volume drained is usually less than 1 litre. If the volume drained is 1 litre or more, this can be used as a distinction between acute and acute-on-chronic retention, particularly if associated with less pain (a finding that is more typical of chronic urinary retention (CUR)). CUR occurs when patients retain a substantial amount of urine in the bladder after each void. However, a defined volume for CUR is more difficult. and the finding of persistent residual volumes of >300 ml (some authors suggest >500 ml) after voiding is often used as evidence of chronic retention, although some patients present with many litres in their bladders. Generally, AUR is painful whilst CUR is not. Although it is usually stated that patients with AUR did not have previous lower urinary tract symptoms (LUTS), it is more likely that many of these patients had not complained of these symptoms before. That is, they may have either not recognized their significance or assumed them to be an inevitable consequence of ageing.
Discharge and follow-up Before discharge, check that the patient’s inhaler technique is adequate, that all medications (inhalers, corticosteroid, antibiotics) have been altered appropriately, and that he or she has and understands a PEF record chart and symptom-based asthma plan. The GP must be informed directly whenever a patient with asthma has needed A&E or hospital treatment following an exacerbation. The patient should be reviewed by an asthma liaison nurse or GP within 48 hours of discharge, and in a specialist hospital clinic after about 1 month.
Aetiology AUR occurs in an obstructed or decompensated lower urinary tract and may be precipitated by the combination of a large fluid intake volume and some delay in micturition resulting in bladder overdistension and consequent reduced bladder contractility. Common causes of retention include constipation, urinary infection, drugs with an anticholinergic or sympathomimetic effect and clot retention. Underlying causes are shown in Figure 1. The aetiology of CUR is more complex and can be divided into high-pressure chronic retention (HPCR) and low-pressure chronic retention (LPCR). The terms ‘high’ and ‘low’ refer to the detrusor pressure at the end of micturition, i.e. at the start of the next filling phase. Bladder outlet obstruction usually exists in high-pressure chronic retention and the voiding detrusor pressure is high, but
FURTHER READING British Thoracic Society, Scottish Intercollegiate Guidelines Network. British guideline on asthma management: a national clinical guideline. Thorax 2003; 58: (Suppl. 1): i1–94. (Essential reading for all clinicians involved in the care of asthma patients.) Cates C J, Rowe B H, Bara A. Holding chambers vs nebulisers for beta-agonist treatment of acute severe asthma. The Cochrane Library 2001; 3. Parameswaran K, Belda J, Rowe B H. Addition of intravenous aminophylline to beta2 agonists in adults with acute asthma. The Cochrane Library 2001; 3. Rowe B H, Bretzlaff J A, Bourdon C et al. Magnesium sulphate for treating exacerbations of acute asthma in the emergency department. The Cochrane Library 2001; 2.
THE FOUNDATION YEARS 1:3
Rebecca Hamm is a Specialist Registrar in urology on the South-West rotation, UK, and is currently working at Taunton and Somerset Hospital, Taunton, UK. Mark J Speakman is a Consultant Urologist and Associate Medical Director at the Taunton and Somerset Hospital, UK. He qualified from Charing Cross Hospital, London, and trained in urology in Oxford and Glasgow. His research interests include benign and malignant prostate disease and bladder function.
25
© 2005 The Medicine Publishing Company Ltd
URINARY RETENTION
α-adrenergic activity: some cases of AUR are associated with a rise in the prostatic intraurethral pressure through an increase in α-adrenergic stimulation (e.g. stress, cold weather, sympathomimetic agents used in cold remedies). Prostatic infarction or prostatitis may contribute to this process. Bladder overdistension also leads to increased adrenergic tone.
Aetiology of urinary retention Obstructive • Mechanical obstruction (e.g. benign prostatic hyperplasia (BPH), urethral stricture) • Dynamic obstruction i.e. increase in smooth muscle tone (e.g. postoperative pain, drugs) Neurological • Interruption of sensory or motor innervation to the bladder (e.g. pelvic surgery, multiple sclerosis, spinal injury, diabetes, psychogenic) Myogenic • Over-distension of the bladder (e.g . post-anaesthesia, high alcohol intake)
A decrease in the stromal:epithelial ratio has been noted in AUR. This may in part explain the effect of the agent finasteride, which is known to act mainly on the epithelial component of the prostate and has been reported to reduce the risk of retention. Neurotransmitter modulation: reduction of non-adrenergic, noncholinergic transmitters (e.g. vasoactive polypeptide (VIP), neuropeptide Y (NPY)), has been postulated as an underlying cause.
1
Presentation
associated with poor urinary flow rates. The constantly raised bladder pressure during both the storage and voiding phases of micturition creates a back pressure on the upper tract drainage and results in bilateral hydronephrosis. Other patients may have large-volume retention in a very compliant bladder with no hydronephrosis or renal failure and these are said to have LPCR. Urodynamic studies in these patients show low detrusor pressures, low flow rates and very large residual volumes. LUTS, however, are usually minimal in CUR, certainly in the early stages, until the onset of nocturnal enuresis, which results from the drop in urethral resistance during sleep, which is overcome by the maintained high bladder pressure causing incontinence – sometimes inappropriately called overflow incontinence.
In acute retention, patients present with lower abdominal discomfort and swelling, an inability to pass urine (or passing only small amounts of urine), and with a palpable mass arising from the pelvis which is dull to percussion. Examination should include a digital rectal examination noting the size and texture of prostate, anal tone and the presence or absence of constipation. Although AUR is primarily a clinical diagnosis, a bladder volume scan (if available) will further confirm the diagnosis before catheterization. Dipstix test of the urine should always be performed and a catheter specimen of urine (CSU) sent if there are signs of infection: urinary infection should be treated. Urea and electrolytes should be checked in all patients with urinary retention. Renal ultrasound is indicated in patients with high-volume retention and in patients with abnormal renal function. Prostate-specific antigen (PSA) testing is best avoided during the acute episode, since any instrumentation of the prostate leads to a spurious rise in PSA.
Epidemiology Community-based studies suggest that 10% of men in their 70s experienced AUR over a 5-year period, and the risk increases to one in three over 10 years. AUR is rare in younger men; men in their 70s are five times more at risk of AUR than men in their fourth decade. It can be calculated that a 60-year-old man would have a 23% probability of experiencing AUR if he were to reach the age of 80. Retention is over ten times more common in men than in women. An underlying neurological cause should always be considered in women. The most common underlying causes in women are infection or inflammation occurring post-partum, or secondary to herpes, Bartholin’s abscess, acute urethritis or vulvovaginitis. AUR is rare in children and is usually associated with infection or occurring postoperatively.
Differential diagnosis This is not usually difficult, but diverticulitis or a diverticular abscess, perforated or ischaemic bowel or an abdominal aortic aneurysm are all recognized as potentially more serious conditions that can be referred into hospital as ‘acute retention’. Urinary retention may occur secondary to any of the above conditions and it is therefore important that the patient is re-examined soon after catheterization to confirm that the symptoms and signs have resolved. Occasionally an obese patient with renal failure may be mistaken for a case of AUR.
Management of AUR (Figure 2) Pathology and pathogenesis
Treatment of acute retention requires urgent catheterization. Whether patients are catheterized at home by a GP, in accident and emergency departments or in surgical/urology wards depends mainly on local circumstances, as does the decision to admit or send home after catheterization. If patients are kept in hospital awaiting definitive treatment, this results in overall longer total hospital stay. The urine volume drained in the first 10–15 minutes following catheterization must be accurately recorded in the patient’s notes, to enable a distinction between acute and acute-on-chronic reten-
Four factors have been implicated in pathogenesis: Prostatic infarction: prostatic infarction caused by infection, instrumentation, and thrombosis, is far more common in prostatectomy specimens after AUR than in cases of clinical benign prostatic hyperplasia alone. This may lead to neurogenic disturbance, preventing relaxation of the prostatic urethra, or to swelling and a rise in urethral pressure.
THE FOUNDATION YEARS 1:3
26
© 2005 The Medicine Publishing Company Ltd
URINARY RETENTION
Management of chronic urinary retention
Management of acute urinary retention after catheterization
Normal renal function
No
Chronic retention
Monitor fluid balance Check renal function daily Elective TURP if fit Long-term catheter if not
Abnormal renal function or upper tract dilatation No
Yes
Symptomatic or complications
Catheter drainage monitor diuresis TURP if fit or LTC or CISC
Yes
Prostate feels benign
No
Further investigation for prostate cancer
No
Teach catheter care and use of flip flow valve/leg bag discharge with date for TURP
Yes
Retention <1 litre/no history of LUTs/obvious precipitating cause
Yes
Commence α-blocker, laxatives/antibiotics TWOC at 48 hours
No
Yes
Regular follow-up of symptoms and creatinine
Urodynamic investigation Good detrusor function Yes
Yes
Successful TWOC
No
Teach catheter care and use of flip flow valve/leg bag dishcharge with date for TURP
TURP if fit or LTC or CISC
LTC or CISC
3
prior to the episode of retention) • loss of the corticomedullary concentration gradient caused by reduced urinary flow through the chronically obstructed kidney • an osmotic diuresis caused by the high urea level. In about 10% of cases this is excessive and requires careful fluid replacement. Daily weighing is an accurate way of monitoring fluid output. After the first 24 hours, fluid replacement should not religiously follow the output, which would perpetuate the diuresis. Potassium levels, which are often high, should be monitored and will usually (but not always) fall with the diuresis. Catheterization is often followed by haematuria; this is caused by renal tract decompression and not usually by the catheter itself. The practice of slow decompression is unnecessary and haematuria usually settles after 48–72 hours. If there is evidence of renal failure, which settles with catheterization, the patient should not undergo a TWOC before a definitive procedure has been considered. If presenting electively through outpatients, the indications for catheterization before TURP in cases of CUR are again renal impairment and water and salt retention; otherwise it is best to avoid catheterization to avoid infection and bladder shrinkage before TURP, but the patients should be listed for early surgery. Patients with low-pressure chronic retention do poorly after TURP, frequently failing to void after surgery even after prolonged periods of catheteritization. A number of interesting debates remain in the management of patients with retention, as follows.
Yes
Discharge on α blocker/finasteride. Review in outpatients with flow rate and residual volume estimation TURP: Transurethral resection of the prostate TWOC: Trial without catheter 2
tion. Less than 800 ml, particularly if associated with a known predisposing factor, is associated with a higher chance of a successful trial without catheter. AUR was previously considered an absolute indication for transurethral resection of the prostate (TURP). However, more recently, other treatments have been considered. AUR is the indication for prostatectomy in 25% of patients in the USA and up to 50% of patients in the UK. A trial without catheter (TWOC) is now considered in most patients. In the UK National Prostatectomy Audit, AUR and CUR accounted for 28% and 26% of the indications for TURP respectively.
Management of CUR (Figure 3) The management of CUR is more complex. Catheterization is less urgent as the condition is generally less painful. Early catheterization is indicated if there is renal dysfunction or upper tract dilatation. Patients must be monitored for a post-obstructive diuresis. They can pass many litres of urine in the first few days following catheterization. The diuresis is due to: • off-loading of retained salt and water (retained in the weeks
THE FOUNDATION YEARS 1:3
No
Urethral versus suprapubic catheterization The principal advantages of suprapubic catheterization are reduction in urinary tract infections (UTIs), less stricture formation and 27
© 2005 The Medicine Publishing Company Ltd
URINARY RETENTION
the fact that it permits TWOC without catheter removal. It could therefore be regarded as the preferred route of catheterization. Disadvantages are that it is a more complex procedure, which not all health professionals are adequately skilled to perform, and also has the potential for serious complications, such as bowel perforation and peritonitis, particularly where there has been previous pelvic surgery. Therefore, it is usually reserved for cases where urethral catheterization has failed, and in some cases of chronic retention where intermittent self-catheterization is not an option and long-term catheterization may be necessary. Urine should always have been withdrawn using an exploratory ‘tap’ with a small needle before trocar and cannula insertion.
Prevention Community-based studies and the placebo arms of long-term randomized studies have identified predictive risk factors for AUR. Risk factors include men >70 years of age with LUTS, an International Prostate Symptom Score (IPSS) >7 (i.e. moderate or severe LUTS), a flow rate of <12 ml/second and/or a prostate volume of >40 cm2 or a PSA >1.4 ng/ml, which is a good proxy for prostate volume. Studies have suggested that hesitancy may also predict a greater risk of subsequent AUR. Placebo-controlled trials have shown that treatment with finasteride for periods >6 months reduces the risk of AUR by over 50%. Long-term use of α-adrenergic receptor antagonists (e.g. alfuzosin, tamsulosin) may reduce the rate of AUR by a similar extent.
TWOC If a policy of TWOC was carried out in all patients with AUR, then about 20% of patients would be expected to have a successful trial and avoid surgery in the long term. With these statistics, it may not be advisable to trial all patients. Factors leading to a high probability of successful TWOC include: • UTI with no previous obstructive symptoms • gross constipation • recently started anticholinergic or sympathomimetic drugs • drained volume <500 ml. Conversely, factors leading to a high probability of unsuccessful TWOC include: • patients >75 years of age • drained volume >1 litre • previous LUTS • voiding detrusor contraction (on urodynamics) of < 35 cmH2O. The duration of catheterization before TWOC alters the chance of a successful trial of catheter removal. In one study, 44% of patients had a successful TWOC after a single day of catheterization, 51% were successful after 2 days of catheterization and 62% after 7 days of catheterization. Higher success rates for TWOC have been reported after treatment with the α-blockers alfuzosin and tamsulosin. These drugs are started on admission and TWOC carried out after 48 hours. Initial success rates increase from 30% to 50% with these drugs. However, if an initial TWOC is successful, over half of these men will experience recurrent AUR over the next year. The role of clean intermittent self-catheterization (CISC) CISC is an alternative to an indwelling catheter. It is a safe, simple and well accepted technique that results in fewer UTIs than indwelling catheterization. There are no external devices and maintenance of sexual activity is possible. It may also increase the rate of successful spontaneous voiding. CISC can be used either instead of an indwelling catheter after an episode of acute or CUR or in patients who fail to void following a prostatectomy (who go into retention secondary to detrusor failure following TURP). Prostatectomy after retention Prostatectomy after AUR is associated with an increased morbidity due to infection, perioperative bleeding and increased transfusion rates as well as up to a threefold increase in mortality. In addition, a higher percentage of men fail to void after TURP compared with men undergoing surgery for symptoms alone.
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© 2005 The Medicine Publishing Company Ltd