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Isn’t it ironic that the acronym for post-op urinary retention – POUR – is exactly what the bladder, sometimes, cannot do following an operation!
Basics
POUR is the inability to urinate after a surgical procedure and a common reason for urology consultation. The surgical procedure that incurred the problem does not necessarily have to involve the urinary tract, and the patient may have had no issues with urination before the surgical procedure. The key factors contributing to this problem are anesthesia, medications, pain, and confinement to a bed or stretcher.
Any form of anesthesia – general, spinal, or regional – can suppress urination at the level of the central nervous system (pontine micturition center) and the peripheral nervous system (sacral spinal cord). General anesthetics are smooth muscle relaxants that may decrease the ability of the bladder to contract effectively. Spinal and epidural anesthetics interfere with nerves going from the spinal cord to and from the bladder. POUR occurs most commonly with spinal anesthesia, followed by epidural anesthesia and general anesthesia.
When my wife had an epidural immediately before our first daughter’s delivery, she could not urinate. She had to have a catheter placed for over one liter of urine in her bladder.
Pain medications – particularly opioids – may profoundly affect urination by blunting the sensation of bladder filling and increasing the resistance to bladder outflow via stimulation of the sympathetic nervous system.
Post-operative pain triggers the sympathetic nervous system and the adrenaline released by the adrenal glands in response to pain and stress. It also decreases bladder contractility and increases the sphincteric resistance to urinary flow. This occurs in both genders but is particularly pronounced in men because of the presence of the prostate gland, which is highly responsive to adrenaline release, resulting in contraction and tightening.
The prone, non-ambulatory position– often necessary for several hours following a surgical procedure — does not lend itself to efficient bladder emptying.
Risk Factors
Risk factors for POUR are the following: male gender, aging, diabetes, benign prostate enlargement, pre-existing unrecognized urinary symptoms, neurological diseases, spinal surgery, orthopedic procedures including total knee and total hip replacement, anal-rectal and colon surgery (particularly those procedures that can affect the pelvic nerves going to the bladder such as colon resection and abdominal-perineal resection), urogynecological procedures, prolonged surgical procedures, when greater volumes of infused intravenous fluids are used, spinal anesthesia, delayed time to ambulation, and post-operative opioid use.
Symptoms
The typical symptoms are an intense urgency to urinate, pain or discomfort in the bladder region, inability to urinate, and perhaps leakage of urine when the bladder becomes over-distended (overflow incontinence). Anesthesia can make these symptoms less apparent by blunting bladder sensation. Physical exam demonstrates fullness in the supra-pubic region because of the distended bladder. A bladder scan is a form of ultrasound technology that non-invasively determines the amount of urine in the bladder.
Note: The urinary bladder typically holds 10-12 ounces under normal circumstances. A patient with POUR may have over one liter of urine in the bladder and, at times, significantly more than one liter.
Management
A bladder catheter needs to be placed to drain the urinary bladder. This hollow, straw-like tube is inserted into the urethra and advanced into the bladder. It can be left indwelling and attached to a drainage bag. Alternatively, an intermittent catheterization regimen can be utilized in which a catheter is not left in but used as necessary to drain the urinary bladder. Suppose the bladder becomes significantly over-distended with more than one liter of urine. In that case, it is considered a physical “insult.” It may take time to heal and recover from over-stretching and loss of tone and contractility. These changes are reversible with bladder decompression by the use of the catheter. Typically, if an indwelling catheter is used, it is left in for 1-3 days before removal and a voiding trial. There is no need to keep the patient hospitalized for this, as POUR can be managed on an outpatient basis.
The patient with POUR is typically placed on an alpha-blocker medication to decrease outlet resistance and facilitate the resumption of spontaneous voiding. Prostate relaxing medications include the following:
Flomax (Tamsulosin)
Uroxatral (Alfuzosin)
Cardura (Doxazosin)
Hytrin (Terazosin)
Rapaflo (Silodosin)
Prevention of POUR
Anticipation is key. Men with obstructive lower urinary tract symptoms and/or a history of prior POUR should be considered for prophylactic and peri-operative alpha blocker medication. Completing surgical procedures as quickly as possible, not overdoing it with intravenous fluids, minimizing intra-operative and post-operative opioid use, and encouraging early ambulation are practical measures to mitigate the risk of POUR. Those at significantly high risk for POUR may be considered for catheter placement during the surgical procedure with continued use until fully ambulatory.
For more information on bladder catheters, please see the video I created a few years ago: Bladder catheters.
