Differential Diagnosis for Persistent Dysuria

Single Most Likely Diagnosis

• Interstitial Cystitis: This condition is characterized by chronic inflammation of the bladder, leading to persistent dysuria, frequency, and urgency. The fact that all tests are negative and symptoms persist despite treatment with phenazopyridine (which is often used for symptomatic relief of dysuria) makes interstitial cystitis a plausible diagnosis.

Other Likely Diagnoses

• Urinary Tract Infection (UTI) with Resistant Organisms: Although initial tests may be negative, the possibility of a UTI caused by bacteria that are resistant to commonly used antibiotics or not detected by standard urine cultures cannot be ruled out. Further testing, such as urine PCR for bacteria, might be necessary.
• Vulvovaginitis: In women, vulvovaginitis can cause dysuria due to external irritation of the urethral meatus. This condition might not be detected by routine urine tests.
• Urethral Syndrome: This condition presents with symptoms of dysuria, frequency, and urgency without evidence of UTI. It could be due to various factors, including urethral irritation or inflammation.

Do Not Miss Diagnoses

• Tuberculosis of the Urinary Tract: Although rare, urinary tuberculosis can cause chronic dysuria and other urinary symptoms. It is crucial to consider this diagnosis, especially in endemic areas or in patients with risk factors, as it requires specific treatment.
• Bladder or Urethral Cancer: These conditions are rare but can present with persistent dysuria. Early detection is critical for effective treatment.
• Sexually Transmitted Infections (STIs): Certain STIs, such as gonorrhea or chlamydia, can cause dysuria. These infections are important to diagnose and treat to prevent long-term complications.

Rare Diagnoses

• Sjögren's Syndrome: This autoimmune disorder can cause interstitial cystitis and other urinary symptoms due to inflammation of the bladder and urethra.
• Eosinophilic Cystitis: A rare condition characterized by eosinophilic infiltration of the bladder wall, leading to symptoms similar to interstitial cystitis.
• Fowler's Syndrome: A rare condition in women characterized by urinary retention due to a non-relaxing urethral sphincter, which can lead to dysuria among other symptoms.

Each of these diagnoses requires careful consideration of the patient's history, physical examination, and additional diagnostic tests to determine the underlying cause of persistent dysuria.