The effectiveness of the ultrasound bladder scanner in reducing urinary tract infections: a meta‐analysis
Alvisa Palese, Associate Professor, School of Nursing, Udine University, Viale Ungheria 18, 331000 Udine, Italy. Telephone: 0039 (0)432 590926.
E‐mail: alvisa.palese@uniud.it
E‐mail: alvisa.palese@uniud.it
Abstract
Aim. To synthesise the evidence available in the literature on the effectiveness of the ultrasound bladder scanner in reducing the risk of urinary tract infection.
Background. Acute urinary retention is the inability to empty the bladder notwithstanding it being full and is frequent in the postoperative period. Using the ultrasound bladder scanner for the measurement of urinary residue, nurses are able to evaluate the presence of urinary retention, monitor the volume and the excessive relaxation of the bladder and avoid unnecessary catheterisations. The association between urinary catheterisation and urinary tract infection is well documented in the literature.
Design. A meta‐analysis was conducted.
Method. An extensive review was carried out by two researchers using multiple databases, including all articles published from 1 January 1986–8 February 2008. No restrictions were adopted with regard to language. Studies on (1) documenting hospitalised patients with a need to evaluate bladder urinary volume, (2) comparing the use of the ultrasound bladder scanner vs. the clinical judgment of the nurses in the evaluation of acute urinary retention followed by a decision regarding whether or not to apply a bladder catheter and (3) those documenting the impact on urinary tract infection associated with catheterisation were included.
Results. A total of 61 articles were retrieved, of which 58 were excluded because they did not meet the inclusion criteria. The overall effectiveness of the bladder ultrasound scanner in the reduction of urinary tract infection associated with catheterisation was OR 0·27 (IC95% 0·16–0·47; p‐value 0·00000294, variance 0·08, weight 12·50).
Discussion. The ultrasound bladder scanner helps to define and monitor bladder urinary volume and therefore, to catheterise patients only when necessary. Although there were numerous factors affecting the clinical heterogeneity of the included studies, the reduction in risk of urinary tract infection associated with catheterisation was consistent.
Conclusion. The use of the ultrasound bladder scanner for evaluating and monitoring the residue volume in immediate postoperative patients, aged 18 or above, reduces unnecessary catheterisations and therefore the risk of urinary tract infection associated with catheterisation.
Relevance to clinical practice. The systematic use of the ultrasound bladder scanner in the peri‐operative period could increase the appropriateness of catheterisation and reduce patient discomfort, costs and days of hospitalisation associated with urinary tract infection associated with catheterisation.
Background
Urinary retention is the inability to empty the bladder notwithstanding it being full; this may be an acute or chronic condition and either complete or incomplete (Abrams et al. 2002). As defined by the American Medical Association (2004), acute urinary retention is the most common complication in the first two–four hours after surgery and may occur in 0·8–35% of patients. This may provoke discomfort, atony of the bladder wall and sometimes prolonged hospitalisation for urinary tract infection (UTI), damage to the bladder (related to excessive relaxation) and chronic nephropathy (The National Institute of Diabetes and Digestive and Kidney Diseases 2007, Kemp & Tabaka 1990). The combination of these complications, as well as patient discomfort and stress and the costs related to longer hospitalisation, highlights the importance of immediate identification of any urinary retention (Wren & Wren 1996, Wynd et al. 1996) using non‐invasive systems.
Urinary retention may be detected and monitored in two ways: with intermittent/extemporaneous catheterisation and with an ultrasound bladder scanner (Addison 2007, Borrie et al. 2001, Coombes & Millard 1994). Catheterisation is a standard procedure (Borrie et al. 2001, Coombes & Millard 1994) and in the case of urinary retention, should be performed only when the bladder volume is at least 100 ml postvoid or at least 250–300 ml without a preceding evacuation (Lee et al. 2007, 2000). As an invasive procedure, catheterisation causes psychological and physical discomfort, embarrassment and increases the risk of UTI: it also has an economic impact related to possible infections, to the materials used and the nursing time necessary for its application and management (Stevens 2005, Frederickson et al. 2000, Broomhead 1986). Catheter‐associated UTIs (CAUTI) are the most common complications associated with their use; they account for approximately 40% of all nosocomial infections (Kalsi et al. 2003, Kunin 2001, Gastmeier et al. 2000). The method of catheterisation (e.g., failure the recommendations of best practice guideline available) and the duration of catheter use (the risk of acquiring bacteriuria is approximately 5% for each day of catheterisation) influence the risk of CAUTI (Cochrane 2007). The majority of CAUTIs are caused by pathogens ascending the urethra: potential reservoirs for bacteria in the catheterised patient include the urethral meatus, drainage bag and connections (Doughty 2006). The best prevention of UTI is based on (1) the assessment of the need for catheterisation before the placement of any indwelling urinary catheter (Pellowe et al. 2001), evaluating its appropriateness in the treatment of the condition affecting the patient and (2) application of the best practice recommendations (Cochrane 2007). Saint (2000) estimated that each episode of UTI requires an additional cost of US$ 676, while the bacteremia related to the use of the bladder catheter even for intermittent use (such as for evaluating acute urinary retention) costs at least US$ 2836. Moore and Edwards (1997) also estimated the cost as approximately US$ 680, while that associated with materials used for a single catheterisation vary from US$ 5.25–16.35.
Having been available since 1980, bladder ultrasound is a non‐invasive method that permits, with minimal training (Krapp 2006), in the case of acute urinary retention, (1) diagnosis of the problem, (2) evaluation of the bladder volume, (3) the decision to perform catheterisation only when the volume is over a cut‐off point. The result of bladder ultrasound is the avoidance of unnecessary catheterisations. Lee et al. (2000) reported that the proportion of unnecessary catheterisations in the neurosurgical population of the National Taiwan University Hospital oscillated between 28·5–29·5%. In their later study in 2007, the same authors compared two groups of patients: the first (168 patients) underwent 143 evaluations with an ultrasound bladder scanner and the second (76 patients) underwent 164 catheterisations each time the clinical judgment of the nurse suggested its opportune use. Assuming appropriate catheterisations as being those performed at bladder volumes over 300 ml, it emerged that 7% were not necessary in the first group, while in the second group 35·3% of those administered were not necessary.
There is an emerging need to analyse the available research comparing the use of the ultrasound bladder scanner followed by the application or not of an intermittent/extemporaneous catheter vs. the clinical judgment of the nurses who decide whether or not to apply an intermittent/extemporaneous catheter and the effect of these procedures in reducing CAUTIs, given that:
- 1bladder ultrasound is recommended for the evaluation of bladder volume in patients with urinary retention because of its easy use, reliability, accuracy and sensitivity (Tseng et al. 2008, Oh‐Oka & Fujisawa 2007, Byun et al. 2003, Araki et al. 2003, Dudley et al. 2003, Topper et al. 1993, Borrie et al. 2001, Anton et al. 1998, Massagli et al. 1989),
- 2acute urinary retention is managed in daily practice by extemporaneous/intermittent bladder catheterisations applied by the nurse on the basis of their clinical judgment (e.g. the number of hours since last voiding, the presence of the bladder globe) (Borrie et al. 2001, Coombes & Millard 1994),
- 3the application of a bladder catheter exposes the patient to the risk of CAUTI (Kalsi et al. 2003, Kunin 2001, Gastmeier et al. 2000),
- 4the best way to reduce the incidence of CAUTIs is to avoid unnecessary catheterisations (Shekelle et al. 1999).
Objective
The objective was to synthesise the evidence available in the literature on the effectiveness of the ultrasound bladder scanner in reducing the risk of UTI.
Materials and methods
Study type
A meta‐analysis was conducted.
Criteria for study inclusion
The inclusion criteria for the studies were as follows:
- •Type of subjects: male and female patients aged 18 or over, those hospitalised for treatment with a need to evaluate bladder urinary volume.
- •Type of intervention: use of the ultrasound bladder scanner vs. the clinical judgment of the nurses in the evaluation of acute urinary retention followed by a decision whether or not to apply a catheter.
- •Type of outcome: occurrence of at least one CAUTI in hospitalised patients, detected before release.
Criteria for study exclusion
Studies documenting different outcome(s), reporting a different type of intervention and/or the intervention but not conforming to an appropriate study design (e.g. quasi experimental studies, RCT) and not reporting sufficient data, were excluded.
Search methods
Electronic databases
A review of the electronic databases Medline and CINAHL was carried out, including all articles published after 1 January 1986. The last review was carried out on 8 February 2008. No restrictions were adopted regarding language, and articles published in languages other than English and Italian were translated into Italian by native translators.
Medline
The following search strategy string was adopted: (BladderScan[Text] OR Bladder Scan[Text] OR Bladder Scanner[Text] OR Bladder Ultrasound[Text] OR Bladder Scanning[Text] OR Portable Ultrasound Device[Text]) AND Urinary Tract Infection[MeSH]. The search was limited to humans (limit: ‘Humans’).
CINAHL
The following search strategy string was adopted: (BladderScan OR Bladder Scan OR Bladder Scanner OR Bladder Ultrasound OR Bladder Scanning OR Portable Ultrasound Device) AND Urinary Tract Infection.
On‐line journals
The Journal of Ultrasound in Medicine was consulted from 1997–July 2008.
Internet
The search engines Altavista, Dica33.net, Google, MSN, Virgilio and Yahoo were consulted, using the following search terms: ‘BladderScan’, ‘Bladder Scan’, ‘Bladder Scanner’, ‘Bladder Ultrasound’, ‘Bladder Scanning’, ‘Portable Ultrasound Device’.
Bibliographies
All the reference materials of the preceding studies were searched (hand searched or, when appropriate, searched in the database) and consulted.
Contact with the authors
The authors of the articles selected using the preceding search methods were contacted by e‐mail (Dai YT, Frederickson M, Graner T, Heller J, Lee YY, Lou MF, Miller EH, Neitzel JJ, Reuter S, Slappendel R, Tsay WL, Weber EWG). Each of them was asked if they knew of any other relevant studies, including those not yet published.
Grey literature
The bibliographical citations reported on the site of the producer of the BladderScan® range were consulted, and the company Eurel S.r.l. of Linate (Milan), the Italian distributor, was contacted by e‐mail to track down unpublished literature.
Data analysis
The odds ratio, the 95% confidence interval, the p‐value, the variance and weight of each study and the overall estimate were evaluated using the Mantel‐Haenszel method according to the fixed‐effects model. Statistical heterogeneity among the studies was evaluated by applying the heterogeneity test and graphically analysing the forest plot. The Software Package StatsDirect Version 2.6.6 (StatsDirect Ltd, Altrincham, UK) was used for the analyses.
Results
A total of 61 articles were found, of which 58 were excluded (Table 1). The three studies reported in Table 2 were included. In the study by Lee et al. (2007), the patients enrolled were neurosurgical (with spinal and brain lesions): in the group subjected to evaluation by bladder ultrasound, there was an average age of 55·6 (SD 18·1) while 51·2% were men; in the control group there was an average age of 63·3 (SD 14·2) and 51·3% were men. Slappendel and Weber (1999) included orthopaedic patients (lesions to: rachis, upper limb, hip/pelvis, lower limb): the patients in the study group had an average age of 45·2 (SD 19·7) and 38% were men; those of the control group had an average age of 45·7 (SD 17·8) and 38·2% were men. In Frederickson et al. (2000), the patients were orthopaedic (lesions to: rachis, hip, knee) and had an average age of 63 (SD 15) with 53% men in the study group, while in the control group there was an average age of 53 (SD 19) and 40% were men. The difference between the average age of the study group and the control group was statistically significant both in Lee et al. (2007) (p‐value = 0·01) and in Frederickson et al. (2000) (p‐value = 0·002), while in Slappendel and Weber (1999) it was not statistically significant (p > 0·05). The ethnicity of the patients under observation was not documented in these studies. In addition, Frederickson et al. (2000) excluded patients with abdominal lesions, pregnancies and obesity.
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