What are the possible causes of bladder pain and increased urinary frequency in a 28‑year‑old woman?

Bladder Pain and Frequent Urination in a 28-Year-Old Woman

The most likely causes are urinary tract infection (UTI), interstitial cystitis/bladder pain syndrome (IC/BPS), or overactive bladder, and you must obtain a urine culture immediately to distinguish between these conditions. 1, 2

Immediate Diagnostic Steps

Obtain a urine culture before any treatment to determine if bacteria are present, as this single test distinguishes infectious from non-infectious causes. 1, 3

Key History Elements to Assess:

• Duration of symptoms: If >6 weeks with negative cultures, consider IC/BPS 4, 2
• Quality of pain: IC/BPS patients describe "pressure" or "discomfort" rather than classic "pain," and symptoms worsen with bladder filling or specific foods/drinks 4
• Timing relative to sexual activity: Post-coital pattern suggests UTI 1, 3
• Response to prior antibiotics: If symptoms persist despite antibiotics with negative cultures, strongly suspect IC/BPS 5
• Urgency characteristics: IC/BPS causes constant urge to void to relieve pain, while overactive bladder causes urgency to avoid incontinence 4

Most Common Causes by Likelihood

1. Urinary Tract Infection (Most Common)

• E. coli causes approximately 75% of UTIs in young women 1, 3
• Presents with dysuria, frequency, urgency, and suprapubic pain 1
• Confirmed by positive urine culture 1, 3
• If recurrent (≥2 infections in 6 months or ≥3 in one year), requires prevention strategy 1, 3

Treatment approach:

• First-line options: nitrofurantoin 100 mg twice daily for 5 days, fosfomycin 3g single dose, or trimethoprim-sulfamethoxazole 160/800 mg twice daily for 3 days (only if local resistance <20%) 1, 3
• Avoid fluoroquinolones due to resistance and stewardship concerns 1, 3

2. Interstitial Cystitis/Bladder Pain Syndrome

• Affects predominantly women of middle age, but can present in younger women 6, 7
• Hallmark: bladder/pelvic pain with frequency and urgency lasting >6 weeks with consistently negative urine cultures 4, 2
• Pain may extend to urethra, vulva, vagina, rectum, lower abdomen, and back 4
• Frequency occurs in 92% and urgency in 84% of IC/BPS patients 4
• Symptoms worsen with bladder filling and improve with urination 4

Diagnostic criteria:

• "Unpleasant sensation (pain, pressure, discomfort) perceived to be related to the urinary bladder, associated with lower urinary tract symptoms of more than six weeks duration, in the absence of infection or other identifiable causes" 4

Treatment approach:

• Start with behavioral modifications: avoid bladder irritants, stress management 2
• Manual physical therapy for pelvic floor tenderness 2
• Oral medications: amitriptyline, cimetidine, or hydroxyzine 2
• Pentosan polysulfate sodium is the only FDA-approved oral therapy 6

3. Overactive Bladder

• Characterized by urgency with frequency, but pain is NOT a primary feature 4
• Patients void to avoid incontinence, not to relieve pain 4
• If pain is present, IC/BPS is more likely 4, 8

Critical Diagnostic Algorithm

1. Obtain urine culture immediately 1, 3

   • If positive → Treat as UTI with appropriate antibiotics based on susceptibilities 1
   • If negative and symptoms <6 weeks → Repeat culture if symptoms persist 1
   • If negative and symptoms >6 weeks → Strongly consider IC/BPS 4, 2

2. Assess symptom pattern:

   • Post-coital timing → UTI more likely 1, 3
   • Constant symptoms worsening with bladder filling → IC/BPS more likely 4
   • Urgency without pain → Overactive bladder more likely 4

3. If recurrent negative cultures with persistent symptoms:

   • Diagnosis is IC/BPS by exclusion 4, 2
   • Do NOT perform cystoscopy or imaging in women <40 without risk factors 3

Common Pitfalls to Avoid

• Never treat asymptomatic bacteriuria in women with recurrent UTIs, as this promotes resistance without benefit 1, 3
• Do not empirically prescribe antibiotics for chronic symptoms without obtaining cultures first 1, 3, 5
• Do not misclassify IC/BPS as "complicated UTI" as this leads to unnecessary broad-spectrum antibiotic use 1, 3
• Do not ignore the diagnosis of IC/BPS when cultures are repeatedly negative—many patients are misdiagnosed and treated with multiple courses of unnecessary antibiotics 5, 8
• Do not obtain "test of cure" cultures after successful UTI treatment if symptoms resolve 3

If Recurrent UTIs Are Confirmed

Prevention strategy (stepwise approach):

1. Behavioral modifications first: Increase fluid intake, void within 15 minutes after intercourse, discontinue spermicide-containing contraceptives, avoid holding urine 1, 3

2. Non-antibiotic prophylaxis: Methenamine hippurate 1g twice daily, D-mannose supplementation, cranberry products, lactobacillus probiotics 1, 3

3. Antibiotic prophylaxis only if above fails: Post-coital single-dose (nitrofurantoin 50mg, TMP-SMX 40/200mg, or trimethoprim 100mg) or daily continuous prophylaxis for 6-12 months 1, 3