|
GPAC: Guidelines and Protocols Advisory Committee Urinary Tract Infections - Macroscopic and Microscopic Urinalysis and Investigation of Urinary Tract Infections Effective Date: May 1, 2005 Summary | Flow Sheet | Patient Guide | Full Guideline in PDF Recommendations and TopicsScopeThe purpose of this protocol is to avoid unnecessary testing in routine cases while allowing physicians to order tests justified by the patient's clinical condition in special cases. This protocol applies to:
It does not apply to individuals under 19 years of age, catheter or bagged specimens, or suprapubic aspirations. Laboratories may now perform a microscopic urinalysis without a preceding macroscopic urinalysis (dipstick) when:
 RECOMMENDATION 1: Urinalysis When UTI Not SuspectedNegative macroscopic-screened urines do not routinely require microscopic examination of urine sediment. Microscopic examination of urine sediment will be performed when requested only under the following conditions:
Note: Other choices for urinalysis on the requisition include:
If one of these is checked, the test will be performed as requested. If both are checked, the request will be treated as Macroscopic → microscopic if dipstick positive. RECOMMENDATION 2: UTI SuspectedIf an uncomplicated UTI is suspected in a patient with classic symptoms and treatment is not conditional on culture or sensitivity results (i.e. if antibiotics have been prescribed), then no further testing is necessary. If an uncomplicated UTI is suspected in a patient with classic symptoms and treatment is conditional on culture or sensitivity, then 'urine culture' alone should be requested. If 'urine culture' and any combination of macroscopic and/or microscopic urinalysis are ordered, urinalysis will be performed according to the rules outlined in Recommendation 1, and urine culture will be performed regardless of the results of macroscopic and/or microscopic urinalysis. If 'urine culture' is requested without an accompanying request for urinalysis, a urine culture will be performed. RECOMMENDATIN 3: UTI Suspected - Conditional Request for CultureWhen a 'urinalysis - urine culture if pyuria or nitrite present' is requested, either a macroscopic or a microscopic urinalysis,* but not both, will be performed. A urine culture will then be performed only if:
* The choice of macroscopic or microscopic urinalysis will be made by the laboratory unless the referring physician requests microscopic. ** 'Positive for white blood cells' must be defined by the local laboratory physician. RationaleThe purpose of this protocol is to avoid unnecessary testing in routine cases while allowing physicians to order tests justified by the patient's clinical condition in 'special cases'. Routine UrinalysisVarious studies have examined whether macroscopic screening urinalysis can predict the need for further microscopic assessment of urinary sediment.1-12 While some studies have supported microscopic assessment of all urines, regardless of macroscopic results,1-3 others support microscopic analysis only in certain patient populations.4 The majority, however, have concluded that microscopic examination of urine sediment is not necessary if initial macroscopic screening is negative.12 Notable exceptions are urinalysis for patients with spinal cord injury, quadriplegic or paraplegic patients with no voluntary urine control, and patients with genitourinary problems (e.g. nephrolithiasis, bladder calculi, congenital or developmental anatomic abnormalities).4 The latter two patient categories account for about half of the false negative macroscopic screening results.4 Macroscopic test results positive for certain components are rarely correlated with positive microscopic examination of urine sediment. A study of 1385 specimens, positive for pH, SG, urobilinogen, bilirubin, ketone, or glucose, found that less than 0.5% were associated with positive microscopic examinations of urine sediment. Macroscopic tests positive for blood (Hb), protein and turbidity, however, are more likely to be associated with positive microscopic examination or urine sediment.4 Macroscopic tests positive for leukocyte esterase and nitrite are highly correlated with positive microscopic examinations of urine sediment.4,13-16 Since high glucose concentration interferes with leukocyte esterase, a glucose concentration greater than 55 mmol/l may be considered an appropriate justification for proceeding to microscopic urinalysis. Investigation of Urinary Tract InfectionThe costs associated with the investigation of urinary tract infection (UTI) are substantial. However, up to 60-80% of all urine samples sent to the lab for culture are reported negative for bacteria.17 To reduce the costs of unnecessary testing in the investigation of UTI, the ordering physician should consider whether the test(s) ordered will modify the patient's management. The likelihood of a significant urine culture in the absence of pyuria or nitrite in a midstream specimen is low.18-20 When a urine culture or conditional request for culture is submitted, a midstream sample must be collected. It is important to follow proper technique to prevent contamination (consult your laboratory for details). If urinalysis is required before urine culture, microscopic urinalysis is preferable to macroscopic because of its higher sensitivity and specificity.19 - 22 Macroscopic (dipstick) urinalysis may, however, provide a useful aid for the rapid diagnosis of urinary tract infections for physicians who do not have access to a microscope. If pyuria is found on the dipstick in the physician's office, further microscopic urinalysis may not be necessary. It is rarely necessary to order both a macroscopic and a microscopic urinalysis with a urine culture except for 'special cases' (see Recommendation 1). Some laboratories may prefer to perform macroscopic urinalysis to facilitate processing since the difference in sensitivity between macroscopic and microscopic is considered to be relatively small. Physicians concerned about the difference in sensitivity may wish to request microscopic urinalysis on the requisition. In uncomplicated community-acquired cystitis, culture is rarely required when antibiotics are being prescribed. Furthermore, follow-up cultures are not routinely indicated in asymptomatic patients with uncomplicated urinary tract infections. References
SponsorsThis guideline was developed by the Guidelines and Protocols Advisory Committee, approved by the British Columbia Medical Association and adopted by the Medical Services Commission. Partial funding for this guideline was provided by the Health Canada Primary Health Care Transition Fund Revised Date: April 1, 2007This guideline is based on scientific evidence current as of the effective date. The principles of the Guidelines and Protocols Advisory Committee are to:
DisclaimerThe Clinical Practice Guidelines (the "Guidelines") have been developed by the Guidelines and Protocols Advisory Committee on behalf of the Medical Services Commission. The Guidelines are intended to give an understanding of a clinical problem, and outline one or more preferred approaches to the investigation and management of the problem. The Guidelines are not intended as a substitute for the advice or professional judgment of a health care professional, nor are they intended to be the only approach to the management of clinical problems. PDF Format Some documents on this Web site are in PDF format and require a PDF reader. If you do not have Adobe Acrobat Reader Version 7.0 or the most recent version of another PDF reader, you can download Adobe Acrobat Reader by clicking on the 'Get Acrobat Reader' icon.
|
 |
|
|
|||
