In patients with suspected pyelonephritis, how useful is the finding of costovertebral (CVA) tenderness?

Bottom line:  A finding of CVA tenderness on physical exam does not by itself significantly raise the suspicion of UTI to confirm diagnosis, but can combine with other findings, such as hematuria and dysuria, to guide decision-making.

Summary:  The diagnostic usefulness of CVA tenderness for UTI can be found in the Diagnose app, which incorporates the information from the JAMA Rational Clinical Exam – Bent S, et al.  Does this woman have an acute uncomplicated urinary tract infection? JAMA. 2002;287(20):2701-2710.

Table 2b of this systematic review summarizes the positive likelihood ratio from two studies, a training set and a validation set, that aimed to identify the predictive value of various clinical findings on the diagnosis of uncomplicated UTI.  Uncomplicated refers to a non-pregnant patient with an anatomically and functionally normal urinary tract, and no history of immunosuppression, diabetes, or recent catheterization or urological procedure.  The pooled positive likelihood ratio of a finding of CVA tenderness was 1.7 (95% CI, 1.0-2.2) and the negative LR was o.9 (95% CI, 0.8-1.0).

Try it:  Uncomplicated UTIs can are fairly common among women.  To see how a positive likelihood ratio of 1.7 can change the level of suspicion, check out the Likelihood Ratiop Nomogram at JAMAevidence (click Diagnosis>Likelihood Ratio Nomogram on the menu.)  Use a pre-test probability of 50% and adjust the likelihood ratio indicator to 1.7.

Here is a brief review of likelihood ratios impact on clinical decision-making.

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About Amy

Clinical Informationist at EUH Branch Library
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