Dr. med. Dirk Manski

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Urinary Tract Infections (3/4): Diagnosis

Review literature: (Krieger, 2002) (Nickel, 2005a) (Nickel, 2005b) (Sussman and Gally, 1999) (Wagenlehner and Naber, 2006) (DGU 2009, S3-guideline for UTI).

Laboratory Tests in Urinary Tract Infections

Diagnostic Work-up of Uncomplicated Cystitis in Premenopausal Women

Premenopausal women with typical symptoms for bacterial cystitis (dysuria and urinary frequency without vaginal discharge) may be treated with antibiotics with no further diagnostic work-up. Urinalysis, urine culture or imaging are not absolutely necessary, since the probability for bacterial cystitis is over 70%, and the diagnostic accuracy will not improve with further work-up [DGU (2009) S3-guideline for UTI].

Urine Sediment or Urine Dipstick Test:

Signs of urinary tract infections in urine analysis are pyuria, (micro-) hematuria and bacteriuria (nitrite positive). In patients with bladder catheterization, the diagnostic value of urine sediment or dip stick test is reduced.

Urine Culture:

Any proof of bacteria in urine culture of a sterile bladder puncture or sterile diagnostic catheter specimen is pathological. For midstream urine specimen or in patients with bladder catheter, there is a significant risk of contamination (false-positiv urine culture results). To differentiate contamination from urinary tract infection, a threshhold of 105 cfu/ml (colony-forming units per ml) was introduced by Kass.

Kass criteria:

In a properly obtainded midstream urine, 105 cfu/ml indicates significant urinary tract infection (Kass, 2002 (reprint)). Two problems are important to acknowledge when using Kass criteria: underdiagnosis and overdiagnosis (20%). In dysuric patients, a threshhold of 103 cfu/ml is sufficient to indicate significant urinary tract infection. High diuresis or urinary frequency lead to a shorter icubation time of urine in the bladder and may thus result in falsely low bacterial counts. In patients with chronic bladder catheterization, urinary tract infection is likely if the bacterial count exceeds 104 and leucocyturia >100/μl is present.

Blood tests:

In urinary tract infection with fever: blood count, CRP, Kreatinin. In high fever and signs of systemic infection, a blood culture should be done. See also section urosepsis for further tests to identify complications of sepsis in severe urinary tract infection.

Diagnostic Work-Up and Imaging in Recurrent Urinary Tract Infections

Urinary Flow:

The measurement of urinary flow may identify subvesical obstruction or bladder emtying disorders.

Ultrasound Imaging:

Intravenous Urography or Computed Tomography:

Intravenous urography has been a routine diagnostic tool in recurrent urinary tract infection. It is used for exact localization of upper urinary tract obstruction or urinary stones, or if anatomical abnormalities of the urinary tract are suspected.

Computed tomography is more sensitive than intravenous urography to identify pyelonephritis, abscess formation, renal or ureteral calculi or intraabdominal diseases causing hydronephrosis.

Voiding cysturethrography:

Voiding cysturethrography is indicated, if vesicourethral reflux, bladder diverticula, chronic pyelonephritis or neurogenic bladder disorders are suspected.

Retrograde Urethrography in Men:

Retrograde urethrography is used to identify the cause of a weak urinary stream or if diverticula of the urethra are suspected.

Radionuclide Studies:

DMSA scintigraphy allows the identification of renal scarring and impairment of renal function. It should be done in children with vesicoureteral reflux and recurrent infections.


Cystoscopy is used to diagnose subvesical obstruction, bladder diseases (stones, diverticula or tumor) and should always be done after significant hematuria.


If history or imaging results speak in favour of micturition disorders, urodynamics should be considered after complete treatment and healing of urinary tract infection.

Index: 1–9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z


Deutsche Gesellschaft für Urologie, S3-guideline for urinary tract infection
Epidemiologie, Diagnostik, Therapie und Management unkomplizierter bakterieller ambulant erworbener Harnwegsinfektionen bei erwachsenen Patienten
AWMF, 2010, Register-Nr. 043/044

Bauer u.a. 2002 BAUER, H. W. ; RAHLFS, V. W. ; LAUENER, P. A. ; BLESSMANN, G. S.:
Prevention of recurrent urinary tract infections with immuno-active E. coli fractions: a meta-analysis of five placebo-controlled double-blind studies.
In: Int J Antimicrob Agents
19 (2002), Nr. 6, S. 451–6

Kass 2002 KASS, E. H.:
Asymptomatic infections of the urinary tract. 1956.
In: J Urol
167 (2002), Nr. 2 Pt 2, S. 1016–9; discussion 1019–21

Krieger 2002 KRIEGER, J. N.:
Urinary tract infections: what’s new?
In: J Urol
168 (2002), Nr. 6, S. 2351–8

Nickel 2005a NICKEL, J. C.:
Management of urinary tract infections: historical perspective and current strategies: Part 1–Before antibiotics.
In: J Urol
173 (2005), Nr. 1, S. 21–6

Nickel 2005b NICKEL, J. C.:
Management of urinary tract infections: historical perspective and current strategies: Part 2-Modern management.
In: J Urol
173 (2005), Nr. 1, S. 27–32

Sobel und Vazquez 1999 SOBEL, J. D. ; VAZQUEZ, J. A.:
Fungal infections of the urinary tract.
In: World J Urol
17 (1999), Nr. 6, S. 410–4

Sussman und Gally 1999 SUSSMAN, M. ; GALLY, D. L.:
The biology of cystitis: host and bacterial factors.
In: Annu Rev Med
50 (1999), S. 149–58

Tauchnitz 1991 TAUCHNITZ, C:
In: HAHN, H (Hrsg.) ; FALKE, D (Hrsg.) ; KLEIN, P (Hrsg.): Medizinische Mikrobiologie.
Berlin, Heidelberg : Springer, 1991, S. 501–507

Wagenlehner und Naber 2006 WAGENLEHNER, F. M. ; NABER, K. G.:
Treatment of bacterial urinary tract infections: presence and future.
In: Eur Urol
49 (2006), Nr. 2, S. 235–44

  Deutsche Version: Diagnostik und Bildgebung bei Harnwegsinfektion