What is the key physical examination finding for suspected pyelonephritis?

Physical Examination for Pyelonephritis

Costovertebral angle (CVA) tenderness is the key physical examination finding for suspected pyelonephritis and is nearly universal in patients with this condition. 1

Essential Physical Examination Findings

Costovertebral Angle Tenderness

• Flank pain or costovertebral angle tenderness is present in nearly all patients with acute pyelonephritis and its absence should prompt consideration of alternative diagnoses. 1, 2
• CVA tenderness is typically unilateral and corresponds to the affected kidney. 3
• The finding is elicited by percussion or palpation over the costovertebral angle (the angle formed by the 12th rib and the vertebral column). 2

Fever Assessment

• Fever ≥38°C is a cardinal sign of pyelonephritis, though it may be absent in up to 20% of patients, particularly in elderly, diabetic, or immunocompromised individuals. 1
• The combination of fever with flank pain/CVA tenderness forms the clinical cornerstone of diagnosis. 1, 3

Additional Physical Findings

• Systemic signs of inflammation including chills, malaise, and general appearance of illness are common. 1
• Nausea and vomiting frequently accompany the presentation. 3
• Lower urinary tract symptoms (dysuria, urgency, frequency) may be present in approximately 80% of cases but can be absent in up to 20%. 1

Enhanced Diagnostic Technique: Sonopalpation

• Point-of-care ultrasound-guided palpation (sonopalpation) can improve diagnostic accuracy by localizing maximal tenderness directly to the kidney parenchyma, particularly in cases lacking classic features. 4
• This technique may be especially useful in patients with atypical presentations or when the diagnosis is uncertain. 4
• Absence of renal tenderness on sonopalpation can help exclude pyelonephritis and redirect diagnostic consideration. 4

Special Population Considerations

Diabetic Patients

• Up to 50% of diabetic patients lack typical flank tenderness, making physical examination less reliable in this population. 1
• Maintain a lower threshold for imaging and additional diagnostic workup in diabetic patients with suspected pyelonephritis. 1

Elderly and Immunocompromised Patients

• These populations may present with atypical or absent fever despite active infection. 1
• Physical examination findings may be subtle or nonspecific, requiring heightened clinical suspicion. 1

Clinical Pitfalls to Avoid

• Do not exclude pyelonephritis based solely on absence of fever, especially in high-risk populations (elderly, diabetic, immunocompromised). 1
• The absence of flank pain or CVA tenderness should raise suspicion for an alternative diagnosis, as this finding is nearly universal in pyelonephritis. 2
• Do not rely on physical examination alone—always confirm with urinalysis showing pyuria and/or bacteriuria, followed by urine culture. 1, 5
• A negative urine dipstick does not exclude pyelonephritis and should prompt re-evaluation of clinical features. 3

Diagnostic Confirmation Algorithm

1. Clinical assessment: Evaluate for flank pain/CVA tenderness + fever ≥38°C (with or without lower urinary tract symptoms). 1
2. Laboratory confirmation: Obtain urinalysis demonstrating pyuria and/or bacteriuria. 1
3. Definitive diagnosis: Urine culture yielding >10,000 CFU/mL of a uropathogen confirms the diagnosis. 1
4. Imaging is NOT indicated for initial evaluation of uncomplicated cases responding to therapy within 48-72 hours. 6, 1