Catheter-induced urethritis: a comparison between latex and silicone catheters in a prospective clinical trial

A controlled randomised prospective study has been carried out on 100 male patients to compare the incidence of urethritis following catheterisation with either latex or silicone catheters. All patients underwent elective cardiac surgery and were catheterised for 48 h with antibiotic cover, and were followed up for 6 months post-operatively. Of those with latex catheters 22% developed urethritis, compared with 2% of those in the silicone catheter group. This difference is statistically significant (P less than 0.01). Two of the former patients developed a decreased urinary flow and both had tight anterior urethral strictures.     

Toxic catheters and diminished urethral blood circulation in the induction of urethral strictures

Local effects of indwelling urinary catheters are poorly characterized. Latex catheter brands of various degrees of tissue toxicity were implanted into the urethra of 27 male piglets. The systemic hemodynamic states varied from normal to hypovolemia, where the circulation changes simulated the extracorporeal perfusion used in open-heart surgery. The urethral epithelial changes caused by the catheters were studied by light ad scanning electron microscopy (SEM). The blood circulation in paraurethral tissue reacted strongly to systemic hemodynamic changes. A reduced local blood flow induced an accumulation of polymorphonuclear leucocytes in the urethral epithelium and subepithelial space in connection with implanted latex urinary catheter strips. This was not seen in normovolemic piglets. Non-toxic wholly silicone control catheter implants did not induce changes. Epithelial cell damage correlated with the tissue toxicity values of implanted catheter strips. In SEM analysis destruction of microvilli and cell membranes was also discovered in connection with a latex catheter brand regarded as non-toxic. The wholly silicone catheters did not cause any detectable changes. The observed cell damage is induced by toxic chemicals dissolving from latex catheters. Local ischemia exacerbates these toxic effects and activates complement cascade. This induces polymorphonuclear granulocyte accumulation in the damaged urethral epithelium leading to demolition and urethral fibrotization. The present findings explain the etiology of the long urethral stricture epidemics seen in open-heart surgery in the early 1980s by showing the interference between indwelling latex catheters and reduced local blood flow.     

Reused silicone catheter for clean intermittent catheterization (CIC): is it safe for spinal cord-injured (SCI) men?

STUDY DESIGN: Study of reusable catheter. OBJECTIVE: To investigate whether a silicone cathether reused over years for clean intermittent catheterization (CIC) was safe for spinal cord injured (SCI) men. SETTING: Maharaj Hospital, Chiang Mai, Thailand. METHOD: A cross-sectional study was obtained from SCI men who had used CIC with a reusable silicone catheter for more than a year. Demographic data, urological management and urinary tract complications focusing on the radiologic status of the urethra were reviewed and analyzed. In addition, two reused and one new catheters were studied under electron microscope for catheter morphology (surface and lumen) and stiffness. RESULTS: There were 28 SCI men included in this study. The average duration of CIC use was 4.8 years and the average time of usage for each catheter was 3 years (range 1-7 years). In all, 26 men previously used indwelling catheterization (ID) during the acute phase. In all, 23 men performed self-catheterization. Regarding urinary complications, three reported urethral bleeding, five had episodes of pus per urethra, five had epididymitis, four had passing stones, 18 had occasional foul smelly urine, 10 developed fever and cloudy urine during the past year. Of 17 patients who had ultrasonography done, four had pathologic findings in kidney and one had bladder calculi. Demographic data, urinary management and complications did not have significant relation to the abnormality of the urethrogram or urinary tract infection. However, where the frequency of CIC was higher, the abnormality of the urethra was lower (P<0.05). All had serum Cr level < or =1.3 mg/dl. Electron microscopic findings of reused catheters for 2 years revealed encrustation but no obstruction in the lumens and 20% increase in stiffness. CONCLUSION: The clinical outcome, especially with regard to urethral abnormalities with this reusable silicone catheter is as good as with a disposable one. However, to reuse urinary catheters, one should consider the increasing risk of infection. For SCI patients in developing countries, CIC with a reusable silicone catheter may be a suitable and safe choice if one cleans and applies it properly to reduce infection. In order to answer the question how long a person in a developing country should use the same silicone catheter, further research should be conducted.     

A strategy for the control of catheter blockage by crystalline Proteus mirabilis biofilm using the antibacterial agent triclosan

OBJECTIVES: Catheter blockage by crystalline Proteus mirabilis biofilm is a common complication in patients undergoing long-term indwelling bladder catheterisation. Previously we have shown that inflating the retention balloons of all-silicone catheters with triclosan solutions prevents the encrustation process. The aim of the present work was to examine whether this strategy is effective in latex-based catheters. METHODS: Laboratory bladder models were fitted with catheters and the retention balloons inflated with water or various concentrations of triclosan. The urine was inoculated with Pr. mirabilis and the times catheters took to block recorded. RESULTS: Control catheters blocked in mean times ranging from 18 to 27 h. The pH of the urine rose from 6.1 to >8.6. In models with latex-based catheters inflated with 1-10 mg/ml triclosan, the urinary pH was controlled, the numbers of organisms in the urine was reduced and the catheters drained freely for the 7 day experimental period. Electron microscopy confirmed that crystalline biofilm was blocking control catheters. Little sign of encrustation was visible on the test catheters. CONCLUSION: Inflating the retention balloons with triclosan could have practical applications in controlling encrustation on both latex and silicone-based catheters.     

Single-blind, randomised, parallel group study of the Bard Biocath catheter and a silicone elastomer coated catheter

A group of 69 community patients undergoing long-term urethral catheterisation for urinary incontinence took part in this study; 33 patients with a mean age of 70.03 years (+/- 16.6) received the Dow Corning Silastic catheter (16 F 10-ml balloon) and 36 patients with a mean age of 75.61 years (+/- 12.6) received the Bard Biocath catheter (16 F 10-ml balloon). Over a 16-week period catheters were monitored every 2 weeks and changed as necessary. The Bard Biocath catheter remained in situ for an average of 89.61 days (+/- 35.31) and the Silastic catheter remained in situ for an average of 56.7 days (+/- 38.8); this difference was statistically significant. Used catheters were analysed for encrustation using scanning electron microscopy (SEM). The average time in situ for non-encrusted Biocath catheters was 83.7 days and 25.28 days for non-encrusted Silastic catheters. It was found that 70% of patients who received Biocath catheters preferred them to their previous catheters whereas only 30% of patients in the Silastic group preferred the trial catheter. The incidence of bypassing was 28% in the Biocath group and 52.8% in the Silastic group.     

Silver alloy coated catheters reduce catheter-associated bacteriuria

The tendency of indwelling catheters to cause urinary tract infection was evaluated in a randomised clinical study of 223 patients. A Foley catheter coated with silver alloy on both inner and outer surfaces was used in 60 patients; 60 others received a Teflonised latex Foley's catheter and the remaining 103 patients were excluded because of antibiotic treatment, diabetes, etc. There was a statistically significant difference in the incidence of catheter-associated bacteriuria (greater than 10(5) organisms/ml) in the 2 groups after 6 days' catheterisation: 6 patients with the silver coated catheter developed bacteriuria compared with 22 who had the Teflonised latex catheter. This suggests that the silver impregnated urethral catheters reduce the incidence of catheter-associated urinary tract infection.     

Meatal strictures after transurethral prostatectomy using latex or polyvinyl chloride three-way catheters.

Because latex rubber catheters have been implicated in urethral stricture formation, the incidence of urethral strictures following transurethral prostatectomy (TUP) and subsequent catheterisation with latex rubber or polyvinyl chloride catheters was compared. A total of 84 patients with benign prostatic hyperplasia (n = 71) or prostatic carcinoma (n = 13) underwent assessment of urethral diameter and subsequent internal urethrotomy prior to TUP. Following resection, 42 patients received three-way self-retaining latex rubber catheters and 42 received similar catheters made of PVC. Catheters were removed when the urine was clear (mean time = 3 days), and no patient required recatheterisation. Urinary flow was assessed in all patients at 6, 12 and 24 weeks after surgery, and diminution of flow with submeatal stricture formation was noted in one patient who had received a latex rubber catheter, and in one who had received a PVC catheter. In this study, the composition of the catheter had no bearing on subsequent stricture formation following TUP.     

Some observations on the diffusion of antimicrobial agents through the retention balloons of foley catheters

PURPOSE: We examined the ability of antimicrobial agents to diffuse through the retention balloons of urinary catheters and inhibit their encrustation by Proteus mirabilis. MATERIALS AND METHODS: An agar diffusion screening test was developed to detect agents capable of diffusing through catheter balloons and inhibiting the growth of P. mirabilis. The effect of inflating the balloons with antibacterials on the ability of P. mirabilis to encrust catheters was tested in laboratory models of the catheterized bladder. RESULTS: Of 18 antimicrobial agents active on P. mirabilis only mandelic acid, phenoxyethanol, nalidixic acid and triclosan diffused through all-silicone catheter balloons to produce zones of inhibition against P. mirabilis. Polyurethane balloons were permeable to gentamicin and fluoroquinolones. Experiments with silicone catheters showed that inflating balloons with mandelic acid (100 gm/l) or ciprofloxacin (10 gm/l) failed to extended the time at which catheters became blocked in models inoculated with P. mirabilis. However, nalidixic acid (50 gm/l) significantly extended the lifespan of catheters (p <0.05). Triclosan (10 gm/l) prevented the increase in urinary pH that induces crystal formation and inhibited the formation of crystalline biofilm, enabling the catheters to drain freely for the full 7-day experimental period. CONCLUSIONS: Inflation of silicone catheter retention balloons with solutions of nalidixic acid or triclosan rather than water should be considered as strategies to control catheter encrustation. Polyurethane balloons are more permeable than silicone balloons to gentamicin and the fluoroquinolones, and they should be investigated as an alternative to silicone or latex in catheter manufacture.     

Pentosanpolysulfate coating of silicone reduces encrustation

BACKGROUND AND PURPOSE: A significant problem associated with catheterization in the urinary tract is the encrustation of the catheter materials. One approach to reducing encrustation is to alter the surface properties of the catheters. We evaluated the effectiveness of coating with pentosanpolysulfate (PPS), a semisynthetic polysaccharide similar to heparin, in reducing encrustation and the foreign-body inflammatory response to silicone stents in the bladders of male New Zealand White rabbits. MATERIALS AND METHODS: Sixteen rabbits were divided into three groups to receive placement in their bladders of uncoated (N = 7), PPS-coated (N = 7), or sham matrix-processed silicone rings (N = 2) via open cystotomy. After 50 days of maintenance on normal food and water, all rabbits were sacrificed, and the air-dried, unfixed silicone ring surfaces were examined by scanning electron microscopy. Bladders and remaining silicone rings were removed and preserved separately. Silicone rings, cleaned of all encrustation, were stained with toluidene blue to determine the presence or absence of PPS coating on the surface. RESULTS: Histologic examination revealed normal tissue in bladder sections exposed to coated silicone rings and an inflammatory response in sections from bladders having uncoated silicone rings. Coating with PPS was associated with an eightfold reduction in the amount of encrustation of silicone and a marked reduction in the inflammatory response of the bladder wall to the foreign body. CONCLUSIONS: A PPS coating may be useful in reducing the encrustation of long-term indwelling silicone stents or catheters in the human urinary tract.     

Safer urethral catheters: how study of catheter balloon pressure and force can guide design

What's known on the subject? and What does the study add? The urethal catheter is a ubiquitous device that has not been modified or improved for safety in the last 20 years, although it can be associated with significant patient harm. This study utilizes force and pressure measurements of the urethral catheter in order to aid in future safety modifications.

OBJECTIVES

• ? To better define urethral catheter balloon pressures and extraction forces during traumatic placement and removal of urethral catheters.
• ? To help guide design for safer urethral catheters.

MATERIALS AND METHODS

• ? Measurements of balloon pressure were made upon filling within the urethra vs the bladder.
• ? Extraction forces were measured upon removal of a catheter with a filled balloon from the bladder.
• ? Models for the bladder and urethra included an ex vivo model (funnel, ‘bladder’, attached to a 30 F tube, ‘urethra’) and fresh human male cadavers.
• ? The mean (sem ) balloon pressures and extraction forces were calculated.

RESULTS

• ? In the ex vivo model, the mean (sem ) pressures upon filling the balloon with 10 mL were on average three‐times higher within the ex vivo‘urethra’ (177 [6] kPa) vs ‘bladder’ (59 [2] kPa) across multiple catheter types.
• ? In the human cadaver, the mean balloon pressure was 1.9‐times higher within the urethra (139 [11] kPa) vs bladder (68 [4] kPa).
• ? Balloon pressure increased non‐linearly during intraurethral filling of both models, resulting in either balloon rupture (silicone catheters) or ‘ballooning’ of the neck of the balloon filling port (latex catheters).
• ? Removal of a filled balloon per the ex vivo model ‘urethra’ and cadaveric urethra, similarly required increasing force with greater balloon fill volumes (e.g. 9.34 [0.44] N for 5 mL vs 41.37 [8.01] N for 10 mL balloon volume).

CONCLUSIONS

• ? Iatrogenic complications from improper urethral catheter use is common.
• ? Catheter balloon pressures and manual extraction forces associated with urethral injury are significantly greater than those found with normal use.
• ? The differences in pressure and force may be incorporated into a safer urethral catheter design, which may significantly reduce iatrogenic urethral injury associated with catheterization.

     

Histological changes in the urinary bladder secondary to urethral catheterisation

The macroscopic and microscopic features of the urothelial response of the human urinary bladder to urethral catherisation are described. The catheter reaction is characterised by a predominantly eosinophilic inflammatory response producing, macroscopically, a papillary mucosal appearance termed polypoid cystitis. The severity of the epithelial inflammatory response correlates significantly with the duration of catheterisation. Urothelial dysplasia confined to the catheter reaction site was noted in 6% of cases. The possible implications of these findings are discussed.     

Toxic catheters and urethral strictures: A concern about types of catheters used in resource-poor countries

Various reports in the literature have confirmed urethral toxicity caused by the use of catheters, mostly latex catheters and their coated versions, resulting in long-segment urethral strictures or strictures located in multiple areas of the urethra. Most catheters used in resource-poor countries, such as Nigeria, are latex catheters with various coatings, such as silicone. The reasons for the widespread use of these potentially toxic catheters are mainly non-availability and/or the high cost of less toxic catheters. We report three cases of urethral strictures following the use of siliconized latex catheters in order to highlight the potential urethral toxicity associated with the use of latex catheters and to draw the authorities’ attention to the need to regulate the types of catheters used in the country.     

The assessment of catheter-induced urethritis using an experimental dog model

A new experimental model for the assessment of urethral catheters is described. Fifty catheters, comprising brands of latex, silicone, teflon-coated latex and polyvinylchloride (PVC) were assessed. The silicone, teflon-coated latex and PVC catheters were shown to cause minimal inflammatory change of the urethral mucosa, whereas the latex catheters showed variable and more marked changes. The model was simple to establish, and gave reproducible results.     

A Comparison of Urethral Profilometry using Microtip and Fiberoptic Catheters

This paper compares urethral profilometry measurements using two different types of catheter: the Millar microtip transducer and the FST fiberoptic catheter. Outcome variables were functional urethral length (FUL), maximum urethral closure pressure (MUCP), and mean pressure/transmission ratio (PTR). Thirty women presenting to the urodynamics laboratory with symptoms of stress urinary incontinence were evaluated with both catheters. All subjects underwent two passive urethral pressure profiles and two dynamic (cough) urethral pressure profiles with each catheter. For FUL and MUCP, the means of the two passive measurements were compared between catheters. For PTR, the means of the two dynamic measurements were compared between catheters. There was no difference in FUL between the two catheter types. The FST measurements of MUCP and PTR were lower than the microtip measurements. Twenty per cent of patients would have been diagnosed with low-pressure urethra with the FST catheter, but not with the microtip catheter. Caution must be used when applying urethral measurements taken with the fiberoptic catheters to standards set with microtip catheters.     

The effect of urease inhibitors on the encrustation of urethral catheters

Encrustation and blockage of indwelling urethral catheters is primarily brought about by infection of the urinary tract by Proteus mirabilis or other urease-producing species. The bacteria colonise the catheter forming a biofilm community within a polysaccharide matrix. The activity of the urease drives up the urinary pH and causes the crystallisation of calcium and magnesium phosphates in the biofilm. We have used a simple physical model of the catheterised bladder to investigate the ability of urease inhibitors to control encrustation. It was observed that acetohydroxamic acid (1.0 mg/ml) and fluorofamide (1.0 μg/ml) restricted the increase in pH of P. mirabilis-infected urine from 9.1 to 7.6. Significant reductions in the deposition of calcium and magnesium salts were also recorded on the silicone catheters. Electron microscopy confirmed that encrustation and occlusion of the catheter lumen was minimal in the presence of the urease inhibitors. The data from this in vitro study suggests that urease inhibitors, particularly fluorofamide, could have clinical applications in the prevention of catheter encrustation and blockage. Received: 22 September 1997 / Accepted: 2 January 1998     

Cytotoxicity of latex urinary catheters

After an epidemic of severe urethral strictures in cardiac surgery patients, all brand latex catheters marketed in Finland were investigated for cellular toxicity with eluates made from the catheters. Four of the seven brands, including the one involved in the stricture cases, showed marked cytotoxicity and inhibited almost all cell growth in various human cell cultures when a 30% catheter eluate was used. DNA histograms of cells cultured with toxic catheter eluate showed inhibition of DNA synthesis. Silicone catheters did not influence cell growth, which correlates with the finding that no new stricture cases were seen after the latex catheters were replaced with silicone ones. Attention is paid to the facts that international standards regarding urethral catheter toxicity are lacking and that catheter quality control is insufficient.     

Urethral strictures following transurethral resection of the prostate. The role of the catheter

Urethral stricture is the most common late complication of transurethral prostatectomy (TURP). The cause is unknown. A prospective, randomised study was undertaken to investigate the role of the transurethral catheter in stricture formation. A total of 205 patients subjected to TURP were studied. Following resection, they were randomly divided into 2 groups: those drained by a transurethral siliconised latex catheter and those drained by a suprapubic siliconised latex catheter. At follow-up, 6 to 24 months later, 17% of the patients in the transurethral group had developed urethral stricture; the corresponding figure in the suprapubic group was 4%. As a consequence of the higher incidence of stricture in the transurethrally drained group, more patients in that group were dissatisfied with the results of the operation. It was concluded that the post-operative transurethral catheter was an important factor in stricture formation following TURP and that transurethral drainage with a siliconised latex catheter resulted in a higher incidence of stricture. This led to a greater number of patients being dissatisfied with the results of the operation, but the catheter did not affect the results in any other way.     

Assessing the effectiveness of different urinary catheters in emptying the bladder: an application of transvaginal ultrasound

The effectiveness of different types of urinary catheters in completely draining the bladder has not been tested. Transvaginal ultrasound, which is able to measure bladder volumes in women from 2 to 175 ml, provides a means of measuring any fluid volume remaining in the bladder following catheter drainage. Using transvaginal ultrasound, the post-catheterisation bladder volumes were measured in 26 female patients; 14 underwent urethral catheterisation using either a 14F short plastic female catheter or a Foley catheter of the same size (balloon not inflated); 12 had an indwelling 12F suprapublic catheter following bladder neck surgery. The mean post-catheterisation bladder volumes after using the short plastic female and Foley catheters were less than 1 ml and 77 ml respectively. A short plastic catheter should be used in women to collect the residual urine volume by urethral catheterisation. A Foley catheter is relatively ineffective in this task. A 12F suprapubic catheter was found to drain the bladder relatively well. The mean post-catheterisation bladder volume was 35 ml. Prior to removing a suprapubic catheter post-operatively, it is recommended that the residual urine volume (measured using the suprapubic catheter) be checked by measuring the post-catheterisation bladder volume (using either a short plastic catheter or transvaginal ultrasound).     

The risk of intra-urethral Foley catheter balloon inflation in spinal cord-injured patients: Lessons learned from a retrospective case series

Background

Inflating the balloon of Foley catheter in urethra is a complication of urethral catheterisation. We report five patients in whom this complication occurred because of unskilled catheterisation. Due to lack of awareness, the problem was not recognised promptly and patients came to harm.

Case series

1. 1.
   A tetraplegic patient developed pain in lower abdomen and became unwell after transurethral catheterisation. CT pelvis revealed full bladder with balloon of Foley catheter in dilated urethra.
    
2. 2.
   Routine ultrasound examination in an asymptomatic tetraplegic patient with urethral catheter drainage, revealed Foley balloon in the urethra. He was advised to get catheterisations done by senior health professionals.
    
3. 3.
   A paraplegic patient developed bleeding and bypassing after transurethral catheterisation. X-ray revealed Foley balloon in urethra; urethral catheter was changed ensuring its correct placement in urinary bladder. Subsequently, balloon of Foley catheter was inflated in urethra several times by community nurses, which resulted in erosion of bulbous urethra and urinary fistula. Suprapubic cystostomy was performed.
    
4. 4.
   A tetraplegic patient developed sweating and increased spasms following urethral catheterisations. CT of abdomen revealed distended bladder with the balloon of Foley catheter located in urethra. Flexible cystoscopy and transurethral catheterisation over a guide-wire were performed. Patient noticed decrease in sweating and spasms.
    
5. 5.
   A paraplegic patient developed lower abdominal pain and nausea following catheterisation. CT abdomen revealed bilateral hydronephrosis and hydroureter and Foley balloon located in urethra. Urehral catheterisation was performed over a guide-wire after cystoscopy. Subsequently suprapubic cystostomy was done.
    

Conclusion

Spinal cord injury patients are at increased risk for intra-urethral Foley catheter balloon inflation because of lack of sensation in urethra, urethral sphincter spasm, and false passage due to previous urethral trauma. Education and training of doctors and nurses in proper technique of catheterisation in spinal cord injury patients is vital to prevent intra-urethral inflation of Foley catheter balloon. If a spinal cord injury patient develops bypassing or symptoms of autonomic dysreflexia following catheterisation, incorrect placement of urethral catheter should be suspected.

     

Toxicity study of first and second generation hydrogel-coated latex urinary catheters

The hydrogel-coated urinary catheter is a novel formulation in which the coating hydrogel polymer is claimed to reduce the level of cytotoxicity frequently associated with the use of latex catheters. This study was undertaken to measure cytotoxicity using in vivo techniques. Twelve first generation and 5 second generation hydrogel-coated latex catheters were evaluated in vivo using canine urethras. The results showed all catheters to cause minimal inflammatory changes of the urethral mucosa (toxicity score 0-1.2/6).