What is Nailfold Capillaroscopy
Nailfold capillaroscopy is a non-invasive imaging technique that directly visualizes the microcirculation of small blood vessels (capillaries) in the nailfold area of the fingers, primarily used to distinguish primary from secondary Raynaud's phenomenon and diagnose scleroderma spectrum disorders. 1, 2
Technical Description
Nailfold capillaroscopy examines the capillary bed at the base of the fingernails using magnification devices. 1, 3 The procedure can be performed using:
- Otoscope 4, 1
- Ophthalmoscope 4, 1
- Dermatoscope 4, 1
- Formal capillaroscopy equipment 4
- Video-capillaroscopy (allows computer storage and longitudinal tracking) 5
The examination typically focuses on the nailfold of the 2nd through 5th digits of the hands. 1
What the Test Shows
Normal Pattern
In healthy individuals, capillaries appear as:
- Homogeneous, parallel arrangement in the last row of capillaries 2
- Hairpin-shaped loops or non-specific variations like tortuous or crossing shapes 2
- Regular capillary density and architecture 3
Abnormal Findings
The test identifies specific pathologic changes that evolve in a predictable sequence:
- Giant capillaries (chronologically the first relevant finding in scleroderma spectrum disorders) 2
- Microhemorrhages (from collapse of giant loops) 2
- Capillary loss/avascularity (areas with absent capillaries) 2
- Neoangiogenesis (ramified/bushy capillaries forming in response to hypoxia) 2
Primary Clinical Applications
Raynaud's Phenomenon Evaluation
Nailfold capillaroscopy is strongly recommended for all patients with Raynaud's phenomenon to distinguish primary from secondary causes. 2, 5 This distinction is critical because:
- Normal capillaroscopic pattern indicates primary Raynaud's phenomenon (benign condition) 5
- Sclerodermic pattern indicates secondary Raynaud's phenomenon with very high risk of systemic sclerosis 5
Systemic Sclerosis
The technique is included in the 2013 EULAR/ACR classification criteria for systemic sclerosis. 1, 3 Three evolutive stages are recognized:
Capillary density serves as a sensitive measure of both skin and muscle disease activity. 1
Other Connective Tissue Diseases
Nailfold capillaroscopy aids in diagnosis and monitoring of:
- Juvenile dermatomyositis (particularly useful for predicting disease severity and monitoring clinical course) 4, 1
- Mixed connective tissue disease 2, 5
- Undifferentiated connective tissue disease 2
Prognostic Value
Beyond diagnosis, capillaroscopy predicts:
- Risk of digital ulcer development in systemic sclerosis 5
- Future visceral complications 5
- Time to remission (persistent capillary abnormalities associated with longer remission time) 1
When to Perform the Test
Patients with puffy fingers, specific SSc-associated antibodies, or other features suggesting prescleroderma should undergo nailfold capillaroscopy. 1
At diagnosis or disease flare, standardized nailfold capillaroscopy assessment is recommended, with regular follow-up assessments during disease monitoring. 4, 1
Assessment Methods
The technique allows for:
- Qualitative assessment (pattern recognition) 2, 3
- Semiquantitative assessment 2
- Quantitative assessment (precise measurement of capillary parameters) 2, 3
Automated systems are currently under development for more standardized evaluation. 2
Key Advantages
- Non-invasive and safe 3, 6
- Rapid and easily applicable 7
- Provides direct visualization of microcirculation 6
- No patient preparation required 3
- Can be performed in outpatient settings 6
Important Limitations
While nailfold capillaroscopy shows promise in other conditions like systemic lupus erythematosus, psoriatic arthritis, and antiphospholipid syndrome, attempts to define specific characteristics for these diseases have failed thus far. 2 The technique requires proper training for accurate interpretation and standardized acquisition methods. 7, 6