Differential Diagnosis for Dysuria and Increased Urinary Frequency with Negative Urine Culture

Single Most Likely Diagnosis

• Urethral Syndrome: This condition, often related to urethral irritation or inflammation, can cause dysuria and frequent urination without a positive urine culture. It's a common issue, especially in women, and can be due to various factors including sexual activity, certain soaps, or other irritants.

Other Likely Diagnoses

• Vaginitis: In women, vaginitis (inflammation of the vagina) can cause symptoms similar to a urinary tract infection (UTI), including dysuria and increased frequency, but without a positive urine culture. Common causes include yeast infections, bacterial vaginosis, and trichomoniasis.
• Prostatitis: In men, prostatitis (inflammation of the prostate gland) can lead to dysuria and urinary frequency. The urine culture might be negative if the inflammation is not due to a bacterial infection that would show up in a standard urine culture.
• Interstitial Cystitis: Also known as bladder pain syndrome, this condition involves chronic pain in the bladder and pelvic region, often accompanied by dysuria and frequent urination. Urine cultures are typically negative.

Do Not Miss Diagnoses

• Tuberculosis (TB) of the Urinary Tract: Although rare, TB can infect the urinary tract and cause symptoms similar to a UTI, including dysuria and frequency. A urine culture for TB is necessary for diagnosis, as standard urine cultures will be negative.
• Sexually Transmitted Infections (STIs): Certain STIs, such as gonorrhea and chlamydia, can cause urethritis, leading to dysuria and increased urinary frequency. These infections may not always be detected by a standard urine culture.
• Kidney Stones: While often associated with severe pain, kidney stones can sometimes cause dysuria and frequency without significant pain. A negative urine culture does not rule out the presence of stones.

Rare Diagnoses

• Bladder Cancer: Though rare, bladder cancer can cause irritative bladder symptoms, including dysuria and frequency. Hematuria (blood in the urine) might also be present, but not always.
• Sarcoidosis Involving the Urinary Tract: Sarcoidosis is a condition that can affect various parts of the body, including the urinary tract, leading to symptoms that mimic a UTI. It's a rare cause of urinary symptoms.
• Eosinophilic Cystitis: A rare condition characterized by an eosinophilic infiltration of the bladder wall, leading to symptoms such as dysuria, frequency, and sometimes hematuria.