Ashiv Patel
The management of urinary retention is one of importance, particularly as most patients presenting with urinary retention can be managed using an ‘ambulatory’ model.
Urinary retention occurs most frequently in men over the age of 60, with this risk increasing with age. Males are 13 times more likely to be affected by acute urinary retention (AUR) than women. Over a five‐year period, 10% of men over 70 will develop AUR whilst 30% of men over 80 will be affected.
An ambulatory approach will result in a reduced financial burden, better utilisation of inpatient beds and an improvement in patient‐based outcomes through a reduction in admissions.
Aside from advancing age, the presence of lower urinary tract symptoms (LUTS), larger prostate volume and previous spontaneous retention are all considered risk factors for urinary retention in men.
Acute urinary retention (AUR) is defined as a painful inability to pass urine, followed by relief on draining the bladder through utilising a catheter. It is normally associated with >500 ml of urine being drained.
AUR can be classified as either being spontaneous or precipitated by an event. If the precipitating cause (e.g., infection) is treated, the retention usually resolves; however, spontaneous retention usually requires more definitive management.
Defined as a non‐painful bladder that is still palpable after voiding and post‐void residual volumes in excess of 300 ml being present within the bladder.
Defined as a painful inability to pass urine, followed by relief on draining the bladder through utilising a catheter. It is normally associated with bladder volumes far in excess of 500 ml, typically 1000 ml or more.
Both benign and malignant prostatic enlargement can cause urinary retention. These patients commonly present with lower urinary tract symptoms (LUTS); however, they may present more acutely with urinary retention.
Due to a narrowing of the urethra, an outflow obstruction can occur secondary to a stricture that results in urinary retention.
Faecal constipation can cause urinary retention by obstructing the urethra.
Infection or inflammation of the bladder, urethra, or prostate can cause obstruction of the urethra and lead to urinary retention.
Urinary retention is precipitated by the obstruction of the urethra by clots formed secondary to haematuria. Any amount of macroscopic haematuria can result in clot retention; however, the subset of patients at greatest risk are those without sufficient bladder irrigation post‐operatively.
Drugs can be a precipitating cause of urinary retention. Drugs that commonly cause urinary retention include anaesthetics, anticholinergics, and sympathomimetic agents.
Abdominal pain and associated pelvic floor contraction can make it difficult for patients to pass urine, and adequate analgesic control is important in order to allow the patient to pass urine.
There are a number of risk factors for urinary retention post‐operatively. These include surgery involving the anorectum or perineum, bladder over‐distension, instrumentation of the lower urinary tract, the use of epidural anaesthesia, and immobility in the post‐operative period.
Pelvic fracture and urethral injury will cause urinary retention because the urine is unable to pass down a disrupted urethra.
Conditions that cause central nervous system disfunction can cause detrusor areflexia or detrusor sphincter dyssynergia. Fowler's syndrome is thought to cause impaired relaxation of the external urethral sphincter and can also cause urinary retention.
Cauda equina compression can be caused by a prolapsed lumbar disc, trauma, and benign or malignant masses. Compression or damage to the S2–S4 nerve roots can result in areflexia of the detrusor muscles and ultimately urinary retention.
Women with cystoceles can suffer from urinary retention if the cystocele obstructs or creates a kink in the urethra. A vaginal support pessary provides a simple solution to correct anatomical position and relieve the issue.
Pelvic masses can cause obstruction of the urethra and result in outflow obstruction and urinary retention.
Injury to the pelvic plexus can cause loss of motor innervation of the detrusor muscle and ultimately urinary retention.
Defined as a condition of increased urine production of >200 ml for two consecutive hours following relief of retention or a total of 3000 ml over 24 hours.
Post‐obstructive diuresis is a possibility when over 1000 ml is drained from the bladder using a catheter. This is a result of solute and fluid accumulation occurring due to prolonged renal obstruction, leading to a diuresis and polyuria through multiple mechanisms.
Post‐obstructive diuresis will normally cease once homeostasis is achieved, but can become pathological and may cause electrolyte abnormalities, hypotension, dehydration leading to hypovolaemic shock and even death. Typical supportive management includes replacing 50% of the urine output by volume with intravenous fluids, but if the patient can freely drink according to their thirst, this can be a more physiologically accurate way of achieving the correct rate of fluid replacement in less severe diuresis.
Taking a full history and examination are central to the initial management of a patient with urinary retention. The most important factors to identify when taking a history from the patient include:
Important factors when examining a patient with urinary retention are examination of the abdomen for a palpable bladder and performing a digital rectal exam in order to ascertain whether prostatic enlargement is a contributing factor in men.
It is paramount to make sure that the drained volume and fluid balance is clearly documented for any patient with urinary retention, particularly in those patients who drain more than 1000 ml of urine when a catheter is inserted. The patient's urine should also be tested using urine dip and sent for culture if positive.
Blood tests to monitor the patient's urea and electrolytes is also of key importance in order to correct any subsequent electrolyte abnormalities, before they become life threatening.
Indwelling urethral catheters are composed of a semi‐rigid tube that blocks the urethra but drains the bladder, they involve multiple lumens, with one controlled by an external valve that allows for the inflation of a balloon to maintain the catheters position in the bladder. Indwelling catheters can be broadly divided into two types; two‐way catheters and three‐way catheters. Two‐way catheters are used for all types of urinary retention; three‐way catheters are reserved for patients who require irrigation of their bladders either after suffering from clot retention secondary to haematuria or post‐operatively.
Indwelling catheters come in a range of sizes and are described by the term ‘French’. This relates to the catheters external circumference and was devised by the Parisian manufacturer of surgical instruments, Joseph‐Frédéric‐Benoît Charrière. Therefore, both two‐way and three‐way catheters will have the same external diameter if they have the same ‘French’ size. However, the three‐way catheter will have the smaller drainage lumen, given the space occupied by the irrigation lumen.
Both two‐way and three‐way catheters have a further sub‐type, which comes with a curved tip called either a Coudé tip or Tiemann tip catheter. This curved tip helps the catheter navigate any areas of constriction particularly constriction caused by an enlarged prostate in men.
Verbal consent is imperative to obtain from the patient, and this involves explaining the need for a catheter as well as what a catheter insertion will involve. The smallest sized catheter that will provide adequate drainage should be used.
The technique utilised is aseptic. Sterile water or saline should be used to prepare the skin around the urethral meatus. Lubricant jelly should then be applied to the urethra and this typically contains local anaesthetic. The catheter should be inserted until the flow of urine confirms it is situated in the bladder. The catheter balloon can then be inflated; however, care must be taken not to inflate the balloon whilst it is intra‐urethral because this may cause damage to the patient's urethra and even urethral rupture.
The absence of urinary flow from the catheter indicates either the catheter is not in the bladder or that the diagnosis of urinary retention is incorrect.
In men, a curved‐tip catheter can be used in order to facilitate entry of the catheter into the bladder. However, if the catheter will not pass into the bladder and it is certain that the patient is in urinary retention, then a flexible cystoscopy guided catheter insertion or supra‐pubic catheter insertion is the next step in management. In extremis, a supra‐pubic needle aspiration of urine can be used to drain enough urine to improve the patient's comfort whilst arrangements are put in place for a more definitive solution.
If a flexible cystoscope is available, this should be the first choice when faced with a difficult catheterisation where a catheter cannot be placed into the bladder.
The flexible cystoscope can be used to enter the bladder under vision and site a guide‐wire into the bladder. A catheter (an open Council‐tip catheter for example) can then be ‘rail‐roaded’ over the guide wire to achieve drainage.
There are several things to consider before attempting supra‐pubic catheterisation. Whether the patient may have bladder cancer and the risk of spread through the created tract, previous abdominal surgery that may have caused adhesions, pelvic fractures, and the presence of a pelvic haematoma, anticoagulation, vascular graft in situ in the pelvic region.
Antibiotic prophylaxis is recommended if there is a concurrent urine infection. Abdominal examination to check for a distended bladder and a BAUS (British Association of Urological Surgeons) recommended ultrasound to identify any interposing bowel in the planned tract. Commence with aspiration of urine using a 21G needle, 2 cm superior to the pubic symphysis.
The suprapubic trocar should then be placed 2 cm above the pubic symphysis and inserted following infiltration of local anaesthetic in the same direction that urine was aspirated.
Patients with chronic or acute‐on‐chronic urinary retention must be considered for admission to monitor their urine output for post obstructive diuresis and blood tests the following day to assess for any electrolyte abnormalities.
Any patient with a difficult catheterisation requiring the use of flexible cystoscopy guidance or the insertion of a suprapubic catheter should be admitted to hospital for monitoring and a decision on definitive treatment.
Patients with a simple ambulatory urinary retention (AUR) (500–800 ml drained volume) will usually be manageable in an ambulatory fashion. Once the precipitating cause is identified and reversed following the insertion of a catheter, the patient can be safely discharged if there are no abnormalities on blood tests and they are not in diuresis. They can be seen in urology outpatients or in a trial‐without‐catheter clinic in order to further assess their needs and the next steps in their management.
The ‘outpatient’ catheter service requires careful planning in order to be able to prevent the need for the patient to re‐attend prior to the planned catheter removal and avoid unnecessary stress and anxiety for the patient. This involves adequate explanation and education of catheter care prior to discharge and the means for the patient to have a point‐of‐contact within the department in case of difficulties or need for supplies. Catheter removal should be timed for a point that minimises indwelling catheter time (thus reducing risk of infection) whilst allowing sufficient time for recovery to optimise chances of successful voiding. For the majority of male AUR, two weeks is considered the standard catheter indwelling time. Medication such as tamsulosin (further discussed in the prostatic obstruction chapter) can lower bladder outlet resistance and maximise chances of success.