Indwelling urinary catheters remain one of the most commonly used clinically invasive devices across the NHS, with over 1 million inserted every year in the UK. This represents up to 24% of all inpatients wearing an indwelling urinary catheter at some point during their stay (Feneley et al, 2015). This figure can be much higher in community settings, with almost 40% of community patients in some areas requiring a catheter (Wagg et al, 2005; Loveday et al, 2014).
Of the multiple recognised risks associated with catheter use, blockage and bypassing represent a large proportion of issues faced in the community setting. This leaves both staff and patients frustrated, with frequent out-of-hours visits or repeated call-outs to manage the pain, discomfort and non-drainage.
Common causes of blockage or bypassing and tips to improve practice
Encrustation
Encrustation is commonly caused by a build up of Proteus mirabilis, a urease-producing bacterium that causes biofilm formation on the catheter surface. This, in turn, encourages the production of magnesium phosphate and calcium crystals in the alkaline urine. These crystals attach to the catheter lumen and eyes, resulting in blockage of the lumen and drainage eyelets (Stickler et al, 2003; Feneley et al, 2015).
For many years, the common response for management of encrusted catheters has been to use bladder-washout techniques or catheter-maintenance solutions to dissolve the encrustation or remove the debris. However, clinical evidence has demonstrated that these are risky interventions, as their administration usually involves breaking the closed sterile drainage system and increases the risk of infection. Further, the acidic solutions may, in some cases, damage the urothelial lining of the bladder, resulting in an inflammatory response. The administration of some bladder-washout/catheter-maintenance solutions also increases the pressure within the bladder due to how their are administered or used (e.g. via a 50 ml syringe or use of pressure with bags designed for gravity administration). This, too, can contribute to significant damage and increase the risk of infection (Turner and Dickens, 2011; Davey, 2015; Feneley et al, 2015; Gibney, 2016). Antibiotics and antiseptics have little effect on encrustation, and acidic catheter-maintenance solutions should be used with caution, as these require breaking the catheter's closed system every time the solution is administered (Davey, 2015). In this scenario, the risk of infection may be reduced with the use of a bladder infusion kit, which allows the washout to be administered via a sterile device through the needle-free sampling port, thereby negating the need to break the closed sterile system. Any use of catheter-maintenance solutions or bladder washouts should be clinically relevant, and the reasons should be documented in the notes (Royal College of Nursing (RCN), 2019).
Antimicrobials used in the balloon inflation solution have been a more recent option for managing difficult catheters in UK practice (RCN, 2019). The evidence behind their use dates back to the 1970s, and their use has been increasing in other countries across Europe and North America, where the use of an antimicrobial solution has demonstrated a positive effect in reducing harmful bacteria, including Proteus mirabilis (Pannek and Vestweber, 2011; National Institute of Health and Care Excellence (NICE), 2017).
Negative pressure
Another cause of a blocked catheter is the increase in negative pressure created by the free drainage catheter, which can lead to the mucosal walls of the bladder being ‘sucked’ into the catheter eyelet holes, causing a disruption to the drainage of urine and resulting in blockage (Geng et al, 2012; Feneley et al, 2015). Additionally, the distance or choice of the drainage bag can have a negative impact on drainage and result in frequent blockage or slower urine drainage (Feneley et al, 2015). It is recommended, therefore, that drainage bags are appropriately supported on a stand or with a body-worn device to reduce the weight pulling on the catheter tubing and bladder neck. They should be emptied frequently enough to maintain the flow of urine and prevent reflux, without interrupting the closed drainage system unnecessarily (Geng et al, 2012; RCN, 2012). It is recommended that the bags not be allowed to fill up more than three-quarters of the way (Loveday et al, 2014). The choice of drainage bag will depend on the reason for the catheter, patient choice, length of tubing required, design and position of the tap, manual dexterity and ability to manage the system and bladder capacity (Yates, 2014).
High pressure with catheter valve systems
Catheter valve systems mimic normal voiding patterns by allowing the bladder to fill and empty on a regular basis, therefore reducing the risk of tissue trauma on the bladder neck and mucosal lining (Woodward, 2013). There are some considerations before engaging the use of a catheter valve: bladder capacity, sensation and the individual's cognitive ability to manage a valve system must be established/assessed (Yates, 2014). The risk of high pressure from a full bladder causing renal damage or any recent surgery on the genito-urinary tract will exclude the use of a catheter valve system.
Poor stability
Non-stabilised catheters can increase the movement of the catheter inside the bladder, leading to unstable detrusor contractions and muscle spasms. This will increase the incidence of bypassing, pain and self-expulsion of the catheter (Newman, 2007; Geng et al, 2012; RCN, 2019). A non-stabilised catheter also increases the risk of trauma on the bladder neck, urethra and abdominal opening (in the case of suprapubic catheters), each of which significantly increases the risk of the patient developing a catheter-associated urinary tract infection (Spinks, 2013; Feneley et al, 2015).
Catheter-associated urinary tract infections
Catheter-associated urinary tract infections (CAUTIs) account for a significant proportion of healthcare-acquired infections (Pellowe, 2009), and the cost of treating CAUTIs is estimated at almost £2000 per episode (Loveday et al, 2014), placing an enormous burden on the healthcare economy. Establishing the cost to a patient's quality of life is difficult to determine, with the risk of serious infection increasing the longer the catheter is in place (Chang et al, 2011; Loveday et al, 2014). Some 45% of all bacteraemia cases caused by Escherichia coli are attributed to the urinary tract and the use of catheters (Abernathy, 2017). It is now a Public Health England focus to reduce all healthcare-associated Gram-negative bloodstream infections by 50% by 2021, and all trusts have been challenged with ensuring that a robust action plan is in place to achieve this by closer monitoring, early detection and appropriate treatment of CAUTIs (NHS Improvement, 2017). Needless to say, avoidance of the use of indwelling catheters or early removal of indwelling catheters will help reduce the incidence of CAUTIs.
Useful resources for clinicians in safe catheter management
NHS Improvement (2019) recently released national clinical documentation to support the safe and effective use of urinary catheters. The RCN (2019) also recently revised and republished their catheterisation guidance document to reflect the most recent evidence available for safe and effective care. There are multiple documents that are free to access and downloadable to use in a variety of health and social care settings.
Conclusion
Catheter blockage is a common complication of long-term indwelling urinary catheter use, and various management techniques and products are available for it. Choices regarding the use of a catheter and its associated devices must be subject to careful patient assessment and include consideration of choice, lifestyle and activity level. Health professionals involved with any element of catheter care have a duty of care to ensure that best practice evidence-based care is offered to patients who need to wear catheters.