Acute Cystitis vs Acute Pyelonephritis
Acute Cystitis and Acute Pyelonephritis are easy to mix up on the boards. Here's a side-by-side comparison — presentation, workup, imaging, and first-line treatment — drawn from our full outlines.
Acute Cystitis vs Acute Pyelonephritis at a glance
- Acute Cystitis: Lower urinary tract infection in non-pregnant, immunocompetent woman with normal anatomy.
- Acute Pyelonephritis: Upper urinary tract infection involving renal parenchyma; fever, flank pain, CVA tenderness.
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Side-by-side comparison
| Feature | Acute Cystitis | Acute Pyelonephritis |
|---|---|---|
| At a glance | Lower urinary tract infection in non-pregnant, immunocompetent woman with normal anatomy. | Upper urinary tract infection involving renal parenchyma; fever, flank pain, CVA tenderness. |
| Classic presentation | Sexually active young woman with sudden dysuria, frequency, and urgency without vaginal discharge or fever — empiric treatment without urine culture is reasonable.; Dysuria (burning with urination); Urinary frequency, urgency; Suprapubic pain or discomfort; Cloudy or malodorous urine; sometimes gross hematuria; Absence of fever, flank… | Fever + flank pain + CVA tenderness + pyuria = pyelonephritis. Add hypotension or organ dysfunction = urosepsis.; Fever (often >38.5°C), chills, rigors; Flank or back pain (unilateral or bilateral); Nausea and vomiting; Lower UTI symptoms — dysuria, frequency, urgency — preceding or accompanying upper tract symptoms; Malaise, fatigue,… |
| Workup / key labs | Clinical diagnosis based on symptoms (dysuria, frequency, urgency, suprapubic pain) supported by pyuria. Urine culture with ≥10^5 CFU/mL (or ≥10^3 CFU/mL with symptoms) confirms but is often not necessary for treatment initiation in classic cases.; Urinalysis (dipstick or microscopy) — pyuria (>10 WBCs/HPF or positive leukocyte… | Clinical diagnosis: classic symptoms (fever, flank pain, CVA tenderness) + pyuria + bacteriuria. Urine culture confirms organism and susceptibility.; Urinalysis with microscopy — pyuria, bacteriuria, WBC casts (specific for upper tract), nitrites, leukocyte esterase; Urine culture and susceptibility — ALWAYS obtain (vs cystitis where… |
| Imaging | Not required for uncomplicated cystitis; Imaging (US or CT) considered for recurrent, complicated, or treatment-resistant UTI to evaluate for stones, abscess, anatomic abnormality | Imaging not required in most uncomplicated pyelonephritis with prompt improvement; CT abdomen/pelvis with contrast if: failure to improve after 48-72 h of appropriate antibiotics, sepsis, suspected obstruction or abscess, recurrent pyelonephritis, atypical course, history of stones, men; Renal ultrasound — first-line in pregnancy and… |
| First-line treatment | Nitrofurantoin monohydrate/macrocrystals 100 mg PO BID × 5 days (avoid if eGFR <30 or pyelonephritis suspected); Trimethoprim-sulfamethoxazole (TMP-SMX) DS PO BID × 3 days — use only if local resistance <20% and patient not exposed in prior 3 months; Fosfomycin 3 g PO × 1 dose — convenient single dose; less effective than 5-day… | Outpatient (mild, hemodynamically stable, tolerating oral, no obstruction):; Fluoroquinolone (pyelo) — ciprofloxacin 500 mg PO BID × 7 days or levofloxacin 750 mg PO daily × 5 days — first-line if local resistance <10%; TMP-SMX DS PO BID × 14 days if susceptible (avoid empiric if resistance unknown); Consider initial single dose of… |
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