Differential Diagnoses for Urinary Tract Infection

Lower Tract Symptoms

The European Urology guidelines suggest that when evaluating a patient with suspected UTI, the key differentials depend on whether symptoms suggest lower tract involvement, and whether the presentation is uncomplicated or complicated 1
Atrophic vaginitis is a consideration, particularly in postmenopausal women, who should be examined for vaginal atrophy 2, 3
Interstitial cystitis/bladder pain syndrome should be considered in patients with chronic symptoms without positive cultures, often with baseline genitourinary symptoms between episodes 4
Bladder or urethral diverticula may present with recurrent symptoms and incomplete emptying 2, 3
Pelvic organ prolapse (cystocele) should be examined for, particularly in postmenopausal women with recurrent symptoms 2, 4

Nephrolithiasis (kidney stones) should be considered if symptoms persist beyond 72 hours or if a stone is suspected, with CT imaging being useful 5
Renal abscess should be considered if there is no response to appropriate antibiotics within 48-72 hours, with contrast CT being the preferred imaging 5, 6
Perinephric abscess has a similar presentation to renal abscess with persistent fever despite treatment 5
Diverticulitis should be considered, particularly if there is a history of prior diverticulitis, and may present with pneumaturia or fecaluria 2, 3
Appendicitis should be considered in patients with right-sided flank pain that may mimic pyelonephritis 7

The European Urology guidelines suggest that anatomical abnormalities, such as urinary tract obstruction, fistulae, and indwelling catheters, increase the risk for complicated UTI 2
Functional abnormalities, such as voiding dysfunction, neurogenic bladder, and high post-void residuals, also increase the risk for complicated UTI 2
Host factors, including pregnancy, diabetes mellitus, immunosuppression, and renal transplant, increase the risk for complicated UTI 1
Prior history of urinary tract surgery/trauma, abdominopelvic malignancy, and recurrent pyelonephritis also increase the risk for complicated UTI 2

Asymptomatic bacteriuria (ASB) is characterized by the presence of a positive urine culture without UTI symptoms, and should not be treated in non-pregnant women, elderly patients, diabetics, or those with recurrent UTIs 1
Pyuria alone is not diagnostic, as it has a low positive predictive value and indicates genitourinary inflammation from many non-infectious causes 9, 7
Urinalysis has low specificity in patients with indwelling catheters or ileal conduits, and bacteriuria is almost always present regardless of symptoms 5
Fever workup in hospitalized patients should not include routine UA and cultures, as UTI/CAUTI rarely causes fever without urinary tract obstruction 9, 7
Genitourinary symptoms in elderly women are not necessarily UTI-related, and baseline incontinence, cognitive changes, or other age-related conditions should be considered 1