Pyelonephritis: Likelihood Ratios

Introduction: Acute Pyelonephritis is usually defined as a UTI plus fever. However, according to the one study that everyone cites (see below), this is simply untrue.

Other diagnostic findings are leukocytosis, CVAT or flank pain, and WBC casts in the urine.

See also Urinary Tract Infection, which has many related diagnostic findings, including CVAT and flank pain.

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Tags: Infection Tag this Diagnosis.

Differential Diagnoses include: Urinary Tract Infection

The likelihood ratios of findings for Pyelonephritis are listed below. See the left navigation bar to change the display.

Pre-Test Probability (Prevalence): %.	Post-Test Probability (Predictive Value): %.	Switch to display mode.
Note that calculating probabilities from more than one** finding is inherently inaccurate because findings are not independent. (For example, using two positive findings that share a common pathogenesis is likely to overestimate the true probability.)

Good Positive Likelihood Ratio
Finding	Result	+LR	-LR
[ + ] hearing loss	+ 0 -	4.7	0.6
Population: women presenting to ED with pyuria AND either: clinically suspected pyelonephritis without fever, or fever. Differential Diagnosis: Urinary Tract Infection Study: Am J Emerg Med. 1997 Mar;15(2):148-51. PMID 9115515

Poorly Diagnostic Findings
Finding	Result	+LR	-LR
[ + ] Blood Cultures		Sensitivity = 11%
specificity not assessed. Contaminant blood cultures counted as negative. Blood cultures did not have a greater sensitivity than urine cultures except in 1/307 patients. Study: Am J Emerg Med. 1997 Mar;15(2):137-40.

Findings With Unspecified Accuracy
Finding	Result	+LR	-LR
[ + ] White Cell Cast		No accuracy specified.
supposedly pathognomonic Study: no study specified.
[ + ] Abdominal CT		No accuracy specified.
contrast is necessary to demonstrate heterogeneous renal parenchyma - however, asymmetric perinephric stranding (which can be seen on non-contrast CTs) is also indicative of pyelonephritis heterogeneous enhancement of renal parenchyma is generally thought to be very sensitive and specific (e.g. more so than US) Study: no study specified.