What Constitutes CVA Tenderness on Physical Examination
CVA tenderness is elicited by percussion over the costovertebral angle (the angle formed where the 12th rib meets the vertebral column) on the patient's back, typically performed with the examiner's fist striking the area with moderate force while the patient is sitting or standing; a positive finding is pain or discomfort reported by the patient at the percussion site.
Physical Examination Technique
The costovertebral angle is the anatomical landmark where the lower border of the 12th rib intersects with the lateral edge of the paraspinal muscles, approximately at the level of T12-L1 vertebrae. To assess for tenderness:
- Position the patient sitting upright or standing
- Place your non-dominant hand flat over the CVA
- Strike your hand with the ulnar surface of your dominant fist using moderate force (firm percussion, not gentle tapping)
- A positive test occurs when the patient reports pain, wincing, or significant discomfort at the site
Clinical Context and Limitations
CVA tenderness is classically taught as a sign of upper urinary tract pathology, particularly acute pyelonephritis or perinephric abscess. The 2024 JAMA Network Open guidelines note that "many patients presenting with [perinephric abscess] present with costovertebral angle tenderness" 1, confirming its clinical relevance in serious renal infections.
Important Caveats About Diagnostic Accuracy
The sensitivity and specificity of CVA tenderness are poor, making it unreliable as a standalone diagnostic test. Research demonstrates:
- For ureteral stones: sensitivity 0.65, specificity 0.50, with positive likelihood ratio of only 1.3 2
- CVA tenderness cannot confirm or exclude diagnoses when used alone 2
- In obese patients, the test becomes even less reliable due to increased skin-to-renal pelvis distance 3
Anatomical Factors Affecting Detection
The distance between skin and renal pelvis significantly impacts whether CVA tenderness can be elicited. A skin-to-renal pelvis distance >66mm substantially reduces the likelihood of detecting tenderness even when renal pathology is present (odds ratio 0.76) 3. This means CVA tenderness has particularly low yield in obese patients and should not be relied upon to rule out renal pathology in this population 3.
Clinical Application
Use CVA tenderness as part of a constellation of findings rather than a definitive test. When positive in the appropriate clinical context (fever, dysuria, flank pain), it supports but does not confirm upper urinary tract infection. When negative, it does not exclude serious pathology, particularly in patients with higher body mass index or increased subcutaneous tissue.