urethral catheter selection

John Robinson RGN, RMN, NDN (Cert), is District ChargeNurse, Catheter Specialist, Bay Community NHS Trust,Morecambe.

march 7/vol15/no25/2001 nursing standard 39

art&sciencecontinencenursing standard: clinical · research · education

URINARY CATHETERISATION is a relativelycommon procedure experienced in acuteand community settings. Patients might

require catheterisation for a variety of reasons.These include acute or chronic urine retention,accurate urine measurement, drainage of hypo-tonic bladder or neurogenic bladder, urodynamicinvestigation, bladder irrigation and pre- andpost-operative management. Urethral catheterscan also be used to manage urinary incontinence,However, indwelling catheters have a number ofassociated complications for the patient (Box 1),and should only be used when all other inter-ventions have failed or are inappropriate (Winn1998). Urinary catheterisation can be intermit-tent or indwelling and the two most commonmethods for catheter insertion are urethral andsuprapubic.

The factors affecting the decision to catheterisea patient are frequently interrelated and multi-factorial and can change over time. Each patientshould be regularly assessed and the availabletreatment options fully discussed with him or herbefore the procedure is carried out. Patients’needs and expectations should also be estab-lished to decide the optimum method and typeof catheter to use.

The large number of urinary catheters availableoffers a variety of options, but also makes selec-tion more complex. The type, size, material anddesign should be considered when selecting themost appropriate catheter for a patient.Choosing the right catheter is crucial to preventassociated risks, minimise complications andpromote patient comfort and quality of life.

Urinary catheterisation is primarily a nursingprocedure and promoting best nursing practiceis integral to enhancing good patient care.Catheterisation is a sensitive issue that requireseffective communication and diplomacy skills,and practitioner confidence and skill canpromote patient comfort and dignity.

The large variety of catheters can raise concernsfor practitioners who are not experienced in thisarea. Some nurses, including students, might nothave dealt with a catheterised patient before.Nurses might be unsure about the indications forusing different types of catheter or the differ-ence between ‘male-length’ and ‘female-length’catheters.

The literature suggests that each of the threemethods of catheterisation – urethral, suprapubicand intermittent – has specific problems(Lowthian 1995, Lowthian 1998, Roe 1991,Schonebeck et al 1987, Woollons 1996).Urologists and surgeons continue to debate theadvantages and disadvantages of urethral andsuprapubic methods of catheterisation (Horganet al 1992, Sethia et al 1987) and their respec-tive management (Peate 1997, Pomfret 2000).Accurate patient assessment and evidence-based decision making are important aspects ofcare; record keeping, including time and date ofinsertion, type and size of catheter used, and anycomplications identified, is becoming an increas-ingly important area of practice (Buckley 1999).

The history of catheterisation is interesting.Around 3000BC, river reeds and onion stemswere used to drain the bladder. This was fol-lowed by the development of metal cathetersusing gold, tin, lead and silver tubes: in the1920s, latex was vulcanised. Latex is a productof the Hevea Brasiliensis tree and is collected bytapping the tree trunk. Chemicals known asaccelerators were added during the process,which resulted in a durable and flexible material.A single hollow drainable tube was then pro-duced. In 1934, Frederick Foley, an Americanurologist, developed a catheter with a separatechannel that could be used to inflate a balloonwith water to keep the catheter positionedinside the bladder. The Foley catheter is a self-retaining, flexible tube which is held in positionby an inflated balloon.

Catheters

Urethral catheter selectionRobinson J (2001) Urethral catheter selection. Nursing Standard. 15, 25, 39-42. Date ofacceptance: December 27 2000

Many patients undergo urethral catheterisation. Selecting the most appropriatecatheter for an individual patient requiresknowledge and a practical understanding ofthe types of catheter available. A number offactors should be considered in catheterselection, including patient needs,indications for catheterisation, the type ofmaterial, the balloon size and the length anddiameter of the catheter. The aim of this article is to provide information that willclarify some of the concerns nurses mighthave regarding urethral catheterisation.

Summary

� Nursing care

� Urinary catheters

These key words are based on subject headings from theBritish Nursing Index. This article has been subject todouble-blind review.

Key words

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Catheter manufacturers are striving to producebetter materials for indwelling catheters, toimprove drainage, resistance to bacterial coloni-sation and reduce encrustation, which frequentlycauses catheters to become blocked (Bard 1987,Roe 1991, Roe 1992). A list of catheters can befound in the Drug Tarrif (DoH 2000), the NHSLogistics Authority Catalogue (NHS LogisticsAuthority 2000), or the Continence ProductsDirectory (Continence Foundation 1999). Themajority can be divided into four categories (Box 2).Packaging Accurate record keeping is essentialto good catheter care and the packaging hasimportant information clearly marked on it. Thisincludes: � The reference number.� The catheter material being used.� The length of the catheter – paediatric, stan-

dard or female length.� Charrière (Ch) size and balloon infil, and

whether the catheter is prefilled or not.� The lot number and expiry date.

Catheter length There are three lengths ofcatheter currently in use: female (23-26cm),paediatric (30cm), and standard (40-44cm). Thestandard-length catheter is now termed the‘male-length’ catheter, which is confusingbecause there is no such thing as a ‘male’catheter. The standard-length catheter must beused on male patients. This length can also beused when catheterising female patients. Somefemales prefer the standard-length catheter;female-length catheters may cause pressure anddiscomfort in the groin area of obese women(Pomfret 1996, 2000). Until the 1980s thestandard-length catheter was the only lengthavailable to catheterise either sex.

The female-length catheter was manufacturedin the late 1980s. This length should only beused for catheterising female patients – if afemale-length catheter is used to catheterise amale patient in error, it could result in severetrauma to the prostatic urethra, urethra, orboth. Disciplinary action could be taken againstthe person who catheterised the patient forusing the wrong length of catheter. Extremecare must be taken to identify the correct lengthof catheter before insertion.

Ideally, the catheter should be categorised asstandard and female length and also by whetherit is suitable for intermittent, short- or long-termuse depending on the material used. It would beuseful if manufacturers printed ‘male/female use’on the packaging of all standard-lengthcatheters and ‘strictly for female catheterisationonly’ on female length-catheters.Charrière size The external diameter of the

catheter is measured in Charrière (Ch), Frenchgauge (Fg) or French (F) units. One Charrière unitis 0.33mm, therefore a 12Ch catheter is 4mmand a 16Ch catheter is 5.3mm in diameter. TheCharrière size determines the type of fluid thecatheter should be used to drain (Getliffe 1993,McGill 1982, Pomfret 2000). Smaller Charrièresized catheters have smaller drainage eyes. TheCharrière size is also important for patientcomfort – a large Charrière size can causeurethral discomfort and trauma. In general, thesmallest diameter catheter that is able to provideadequate urine drainage should be used(Pomfret 2000).

The urethra is lined with paraurethral glands,which produce a mucus substance that lines theurethra and protects against ascending infec-tion (Norton 1986, Wilson and Waugh 1996).This lining is flushed away on micturition, butburning or stinging on micturition could indi-cate the presence of cystitis, or a urine infec-tion. However, in catheterised patients themucus coating is not flushed away and drainsaway by gravity and peristaltic action. Thisresults in a dried staining to the patient’s under-wear or a dark dried coating outside the urethraand on the catheter surface.

The smaller the Charrière size, the easier it isfor the mucus to drain away. The higher theCharrière size and the longer the catheter is insitu, the greater the risk of the catheter pressingagainst the urethral wall, which could preventdrainage from the paraurethral glands. Thiscould result in inflammation of the urethrawhich can result in urethritis or another ascend-ing infection (Blandy et al 1989).

In addition, catheters of a high Charrière sizewill not move as easily as a smaller size inside theurethra, which could cause urethral irritation andsores (Lowthian 1998). Charrière sizes, colourcoding and indications for use are outlined inTable 1.

Inflation valves are colour coded according tothe Charrière size. The make, material, Charrièresize and balloon infil is printed on most valves.

Practitioners should avoid inserting a highCharrière sized catheter immediately after usinga small Charrière size – for example, inserting a18Ch catheter directly after 12Ch catheterunless the patient’s condition determines that ahigher size is required, such as in haematuriawith large clots. If the patient needs a higherCharrière size, higher sizes should be introducedgradually to avoid causing trauma by suddendilatation of the urethra. If a large Charrière sizeis used, the patient should be regularly assessedand, where possible, a smaller Charrière sizeshould be inserted.

Urethral dilation can result in urethral sway –movement of the smaller size catheter inside the

Selecting catheter size

40 nursing standard march 7/vol15/no25/2001


� Bladder irritability/spasm� Bypassing� Urine/urethral

infection/bacteraemia� Catheter blockage� Trauma (accidental traction)� Haematuria� Urethral perforation� Catheter encrustation� Bladder calculi� Urethral stricture� Neoplastic changes(Lowthian 1998)

Box 1. Catheter-relatedproblems

� Foley (soft/non-rigid)indwelling catheters forshort- to medium-term use(up to 28 days dependingon the material used).These are not rigid likesome specialised catheters

� Foley (soft/non-rigid)indwelling catheters formedium- to long-term use(up to 12 weeks)

� Rigid (specialised) cathetersfor urological use madefrom plastic and reinforcednylon (three to five days)

� Single-use plastic cathetersused for intermittent self-catheterisation (ISC)

Box 2. Different categoriesof catheter

urethra – and it might be necessary to changethe Charrière size in stages to avoid this. Whenassessing patients for catheter selection, it isimportant to use the smallest Charrière size andballoon infil possible, to avoid catheter-relatedproblems.

Balloon infill can vary from 2.5-5ml in paediatriccatheters, 10-30ml in adult catheters and 20-50ml,and even up to 80ml, in specialised urologicalcatheters. The correct balloon infill is printed onthe packaging. However, balloon infill should beno greater than 10ml for routine use. The 30mlballoon was designed to aid haemostasis byadding downward pressure on the bladder neckfollowing prostatic surgery.

Infilled catheter balloons add weight to thebladder neck, internal sphincter valve and pelvicfloor. A 10ml balloon weighs 17g comparedwith a 30ml balloon which weighs 48.2g. Thegreater the balloon infill, the greater the weightpressing down on the bladder neck and pelvicfloor. If the pelvic floor is weak, the catheter candislodge or, in some cases, fall out with the bal-loon still inflated. The bladder in the normalstate is designed to stretch on filling with urineand to shrink on voiding. However, with acatheter in situ the bladder remains shrunk andthe inflated catheter balloon rests on the base ofthe bladder.

Using a high balloon infill means that the bal-loon surface comes into contact with the bladderwall. The greater the balloon infill the higher theballoon sits inside the bladder, which means thecatheter tip can irritate the trigone area. Thisstimulates the bladder muscle which can causespasm, urinary bypassing, haematuria, traumaand possible erosion of the bladder wall. Careshould be taken to ensure that the balloon isfully deflated before catheter removal. Removalcan also cause urethral trauma, as the ballooncan become creased on deflation causing trau-ma (Robinson 2000, Semjonow et al 1995).

Catheter balloons are either prefilled or non-prefilled. Currently, only one company producesprefilled catheters. Non-prefilled catheters shouldbe inflated with sterile water (Belfield 1988). Tapor boiled (cooled) water will stagnate and maycross through the balloon membrane into thebladder, causing infection. Tap water also con-tains many chemicals. Normal saline will evapo-rate and resultant salt crystals can block the nar-row infill channel, making balloon deflation diffi-cult. Air should never be used as the cathetermay float above the level of urine in the bladder.

Care must be taken not to over- or under-inflate the balloon infill (Belfield 1988, Britton etal 1990, Chrisp et al 1990, Gulmez et al 1996).

Risks associated with over-inflation are: � Balloon rupture leaving fragments inside the

bladder. � Distortion of the catheter/balloon inside the

bladder. � The catheter tip can rise and irritate the

trigone area. � Irritation of the detrusor muscle. � Pain, spasm, bypassing and haematuria.Risks associated with under-inflation are:� Catheter dislodgement into the prostatic urethra

(males) and urethra in both sexes.� Drainage eyes can become blocked if they

enter the balloon area.� Failure of the catheter to drain urine and

catheter dislodgement.� Bladder neck and urethral irritation, bypassing,

pain, haematuria and urethral trauma

Catheters are made from various materials,which determine use and how long the catheterremains in situ (Pomfret 1996, Woollons 1996).Catheters can be made from plain latex, bondedlatex, plastic, pure silicone or nylon re-inforcedmaterials (used in specialised catheters for uro-logical use). Choosing the appropriate catheter

Catheter materials

Balloon infill size

march 7/vol15/no25/2001 nursing standard 41

Charrière size Colour coding Indications for use

10Ch/3.3mm Black Initial catheterisation (female). Clear urine.No grit (encrustation), debris, or haematuria

12Ch/4mm White Initial catheterisation (male or female)Clear urine, no grit, debris, or haematuria

14Ch/4.7mm Green Initial catheterisation (male or female). Clear urine, no grit or debris, no haematuria

16Ch/5.3mm Orange Initial catheterisation (male). Clear or slightlycloudy urine, both sexes. No or mild grit.Light haematuria with no clots

18Ch/6mm Red Initial catheterisation (male). Moderate toheavy grit and debris. Haematuria withmoderate clots

You are advised to seek urology guidance on the use of charrière sizes 20-24 asthe patient may require urological intervention

20Ch/6.7mm Yellow Avoid unless urine is very cloudy, with heavygrit and debris. Heavy haematuria with large clots. Following prostatectomy andbladder surgery

22Ch/7.3mm Violet Severe haematuria with large blood clots.Following prostatectomy and bladder surgery

24Ch/8mm Blue Severe haematuria with large blood clots.Following prostatectomy and bladdersurgery

Table 1. Urethral catheter charrière sizes, colour coding and indications for use


REFERENCESBard (1987) You, Your Patients and

Urinary Catheters. Crawley, WestSussex, Bard Ltd.

Belfield P (1988) Urinary catheters.British Medical Journal. 296, 6625,836-837.

Blandy J et al (1989) Catheters andcatheterisation. In Blandy J et al (Eds).Urology for Nurses. First Edition.Oxford, Blackwell ScientificPublications Ltd.

Britton R et al (1990) Catheters: makingan informed choice. ProfessionalNurse. 5, 4, 194-198.

Buckley R (1999) Keep it legal. NursingTimes. 95, 6, 75-77.

Chrisp J et al (1990) Foley catheterballoon puncture and the risk of free-fragment formation. BritishJournal of Urology. 66, 5, 500-502.

Continence Foundation (1999)Continence Products Directory.London, Continence Foundation.

Department of Health (2000) Drug Tarrif.London, The Stationery Office.

Evans A et al (2000) Bladder washouts inthe management of long-termcatheters. British Journal of Nursing.9, 14, 900-906.

Getliffe K (1994) The use of bladderwashouts to reduce urinary catheterencrustation. British Journal ofUrology. 73, 6, 696-700.

Getliffe K (1993) Care of urinarycatheters. Nursing Standard. 7, 44,31-36.

material is important as certain materials aremore resistant to encrustation. Encrustationoccurs when urine pH is greater than 7.2(Getliffe 1994, Evans et al 2000). Materialdeposits of struvite (ammonium, magnesiumand phosphate) and calcium phosphate accu-mulate, which can lead to partial or completecatheter blockage (Morris et al 1997).

Practitioners should not be afraid to try differ-ent catheter materials to establish which suits apatient’s needs. Before selecting a catheter it isimportant to check if the patient has a latex allergy– not only in relation to the catheter material, butin terms of sterile glove use (Woodward 1997).Foley catheters, the most common used in hos-pital and community settings, can be divided intotwo subcategories: short-to-medium-term andlong-term catheters.

PolyvinyI chlorine or plastic There are twotypes of catheter made from this material. In theindwelling balloon version, the balloon is madefrom latex. However, these indwelling cathetersare fairly rigid and therefore are rarely used.They can be left in situ for 7-14 days. Thesecond type is a single, non-ballooned catheter,which is mainly used for intermittent self-catheterisation (ISC). These catheters are forsingle use (ISC) or as directed by local policy.Plain latex This type is very rarely used. It has athin outer coating of silicone to aid insertion.The surface is not smooth and is prone toswelling, caused by the absorption of body fluidsthrough its surface. This causes the externaldiameter of the catheter to increase whiledecreasing the drainage lumen. They are proneto encrustation. The lifespan is 7-14 days.Polytetrafluoroethylene (PTFE) This is a latexcatheter which is bonded with Teflon, making itsmoother than plain latex catheters and easierto insert. This material also reduces theabsorption of body fluid through the cathetersurface. These catheters are for medium-termuse, with a lifespan of up to four weeks.

Silicone elastomer This is a latex catheter withsilicone bonding to the outer and inner surface.This makes both surfaces smooth and reducesthe potential for encrustation. The siliconeelastomer coating makes the latex lessabsorbent. The catheter lifespan is 12 weeks.Hydrogel This is made of latex, bonded with ahydrogel coating, which the manufacturers stateis more compatible with body tissue. This surfacereduces bacterial colonisation and encrustation(Pomfret 1996). The hydrogel surface absorbs a

small amount of body fluid to keep it smooth,reducing friction between the catheter andurethral surfaces. The lifespan is 12 weeks.Polymer hydromer Latex is bonded withpolymer hydromer to create a material suitablefor long-term catheter use. Similar to hydrogelcatheters, the surface of this catheter absorbs asmall amount of body fluid to keep the surfacesmooth. The catheter lifespan is 12 weeks.

These catheters all contain latex and shouldnot be used in patients who have a latex allergy.Pure silicone This is a latex-free catheter foruse in patients with latex allergy. However, theballoon material allows diffusion to occur – thewater in the balloon slowly passes through theballoon membrane into the bladder. Theballoon infill should be checked and correctedhalf way through its lifespan, otherwise theballoon will slowly deflate causing the catheterto dislodge or fall out. The advantage of thistype is that the catheter walls are thinner andthe internal drainage channel is equal to ahigher Charrière size, for example 12Ch = 14Ch(Getliffe 1993, Woollons 1996). The lifespan isup to 12 weeks.

Selecting the most appropriate catheter length,material and balloon infill reduces the risk ofcatheter-related problems, such as trauma,blockage, haematuria, urethral perforation andencrustation. In using small Charrière sizes (12-16 Ch) with an appropriate balloon infill (10ml)nurses can enhance patient comfort. Guidanceshould be sought from suitably qualified andexperienced staff before using larger sizedcatheters.

Consultation with the patient and his or hercarers is important to establish the patient’s indi-vidual needs and discussion should occur beforethe patient is catheterised. Patients and carersshould be offered explanation and clarificationregarding the procedure and ongoing cathetermanagement. This can help to allay the patient’sfears and anxieties, and enhance understandingof the reasons for catheterisation and the needto report any problems that occur while thecatheter is in situ.

Catheterisation is often termed a ‘basic nurs-ing task’. However, choosing the correctcatheter to meet each patient’s needs requires agood understanding of the indications and rea-sons for catheterisation, experience of cathetermanagement, and knowledge of the differentcatheters available. By integrating clinical experi-ence with the relevant theory, nurses canimprove catheter selection and offer patientsreassurance and comfort while maintaining ahigh standard of care

Conclusion

Long-term catheters

Short-to-medium-term catheters

42 nursing standard march 7/vol15/no25/2001


Gulmez I et al (1996) A comparison ofvarious methods to burst Foleycatheter balloons and the risk of free-fragment formation. BritishJournal of Urology. 77, 5, 716-718.

Horgan A et al (1992) Acute urinaryretention: comparison of suprapubicand urethral catheterisation. BritishJournal of Urology. 70, 2, 149-151.

Lowthian P (1998) The dangers of long-term catheter drainage. BritishJournal of Nursing. 7, 7, 366-379.

Lowthian P (1995) An investigation ofthe uncurling forces of indwellingcatheters. British Journal of Nursing.4, 6, 328-334.

McGill S (1982) Catheter management:it’s the size that’s important. NursingMirror. 154, April 7, 48-49.

Morris N et al (1997) Which indwellingurethral catheters resist encrustationby Proteus mirabilis biofilms. BritishJournal of Urology. 80, 1, 58-63.

NHS Logistics Authority (2000) NHSLogistics Authority Catalogue.Normanton, Elanders Hindson.

Norton C (1986) Catheterisation. InNorton C (Ed). Nursing for Continence.Beaconsfield, Beaconsfield Publishers.

Peate I (1997) Patient managementfollowing suprapubic catheterisation.British Journal of Nursing. 6, 10, 555-562.

Pomfret I (2000) Catheter care in thecommunity. Nursing Standard. 14, 27,46-51.

Pomfret I (1996) Catheters: design,selection and management. BritishJournal of Nursing. 5, 4, 245-250.

Robinson J (2000) Removing catheters.Journal of Community Nursing. 14,12, 8.

Roe B (1992) From Pompeii to thepresent. Nursing Times. 88, 31, 57-60.

Roe B (1991) Catheters: looking at theevidence. Nursing Times. 87, 37, 72-74.

Schonebeck J et al (1987) The dangers ofcatheterisation: 12 photographs. InSchonebeck J, Hakansson L (1987) (Eds)The Atlas of Cystoscopy. Sweden, Gruneand Stratton. Issued by Molnlycke.

Semjonow A et al (1995) Reducingtrauma whilst removing long-termindwelling balloon catheters. BritishJournal of Urology. 75, 2, 241.

Sethia K et al (1987) Prospectiverandomised controlled trial of urethralversus supra-pubic catheterisation.British Journal of Surgery. 74, 7, 624-625.

Wilson KJW, Waugh W (1996) Protectionand survival. In Wilson KJW, WaughW (Eds). Ross and Wilson: Anatomyand Physiology. Eighth edition.London, Churchill Livingstone.

Winn C (1998) Complications withurinary catheters. Professional Nurse.13, 5 (Suppl), S7-10.

Woodward S (1997) Complications ofallergies to latex urinary catheters.British Journal of Nursing. 6, 14, 786-792.

Woollons S (1996) Urinary catheters forlong-term use. Professional Nurse. 11,12, 825-832.

urethral catheter selection

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