Glossary
Nailfold capillaroscopy
A magnifier on your fingernail bed and about ten minutes is the whole of this test. It reads the smallest blood vessels in your body. What it finds there says a good deal about what comes next, and it says more when it comes back normal than when it doesn't.
What the research found.
One study looked at 759 people with Raynaud's and sorted their results into three groups. It found a normal pattern in 354, a nonspecific one in 159, and a scleroderma pattern in 246. The scleroderma pattern turned up in 88 percent of people with systemic sclerosis and in 13 percent of those with rheumatoid arthritis.
One study ranked the individual measures against each other. Capillary loss separated the groups best, with an area under the curve of 0.905 whose true value sits from 0.869 to 0.942. Widened vessels came next at 0.863, then giant vessels at 0.835, while tiny bleeds scored 0.720 and branching vessels 0.604.
Bournia and colleagues, Clinical and Experimental Rheumatology, 2020
One study followed 34 people with early systemic sclerosis for three years, and 8 of them went on to definite disease. That works out at 23.5 percent of the group. An active or late pattern at the start predicted it, at an odds ratio of 30.0 whose true value sits from 2.1 to 421.1.
Zumstein Camargo and colleagues, Clinical Rheumatology, 2019
One study followed 86 people with systemic sclerosis and looked at how far the vessel damage had gone. The severity of that damage correlated with overall disease severity at 0.55, at P under 0.001. A late pattern predicted calcium deposits in the tissues, at an odds ratio of 27.22 whose true value sits from 5.56 to 133.33.
What the test is
Nailfold capillaroscopy is a close-up look at the tiny blood vessels sitting at the base of your fingernail. A drop of oil goes on the skin, and then a magnifier or a small video camera looks at it. That is genuinely the whole of the test, start to finish.
Several of your fingers get checked, and the whole thing is over in minutes. Nothing goes into you, nothing gets cut, and people are usually surprised by how little there is to it. The vessels being looked at are called capillaries, and they're the smallest in your body, where blood finally reaches the tissue it feeds.
Why fingernails
There's a good reason this gets done where it gets done. In most of your skin these vessels loop away from the surface, so from above you'd see a dot rather than a vessel. At the nailfold they run flat, parallel to the skin, which means you can see one vessel end to end.
Almost nowhere else on the body offers that, and nothing has to be cut to do it. It's a rare chance to look straight at circulation at its smallest scale. That's just where several of these illnesses do their damage, so the site of the test isn't an accident.
What they're looking for
Four things, roughly, and they don't count equally. One of the four holds most of the weight, and it isn't the one people expect. First, whether vessels are missing, then whether the ones that remain are widened, then whether any are so enlarged they count as giants, and last whether there's been bleeding around them.
One study ranked those measures against each other in telling systemic sclerosis and its relatives apart from other causes of Raynaud's. Capillary loss separated the groups best, with an area under the curve of 0.905, from 0.869 to 0.942. Widened vessels came next at 0.863 and giant vessels at 0.835.
The other two did much worse than either of those. Tiny bleeds managed 0.720 and branching vessels managed 0.604, which is close to no better than chance. So how many vessels have gone counts for more than how strange the survivors look, which is not what most people would guess.
What a normal result is worth
This is the part worth understanding, because it's the opposite of how most tests work. Get it the wrong way round and you'll misread your own result when it arrives. One study looked at 759 consecutive people with Raynaud's and found a normal pattern in 354 of them, a nonspecific one in 159, and a scleroderma pattern in 246.
The absence of a scleroderma pattern had a negative predictive value of 88 percent. Its positive predictive values ran low, which is the reverse of what most people expect a test to do. Those two numbers are the point of this section.
Put plainly, this test is much better at reassuring you than at diagnosing you. If you were sent because your fingers go white and painful in the cold, a normal result makes the most feared explanation much less likely. That's usually the question that sent you in the first place.
What an abnormal result is worth
Less on its own, because the scleroderma pattern isn't confined to scleroderma. It turns up across several illnesses, and that study is where the numbers for it come from. It found the pattern in 88 percent of those with systemic sclerosis, 71 percent with mixed connective tissue disease, 33 percent with primary Sjogren's syndrome, 17 percent with lupus, and 13 percent with rheumatoid arthritis.
So an abnormal result cuts the field down without settling it. That's why the next step is a conversation rather than a conclusion. Nobody should read an abnormal capillaroscopy as a diagnosis, and the people who order it don't read it that way either.
Two other studies show how far the pattern spreads. One followed 190 people with antisynthetase syndrome, a scleroderma pattern showed in 35.3 percent of them, and of those only 47 percent had Raynaud's at all. One followed 41 young people with childhood-onset lupus, small vessel damage showed in 68.3 percent, and a scleroderma pattern showed in 7 who had no scleroderma symptoms whatsoever.
The three stages
An abnormal result gets sorted into three stages, and they run in order. Early comes first, then active, and then late. Early means a few giant vessels and bleeds with the numbers still normal, active means more of both with vessels starting to disappear, and late means heavy loss with odd branching vessels filling the space.
That staging holds real information rather than being a label for the file. So it's worth asking which stage you're in. That's a different question from whether the test came back abnormal, and it's the one with the answers in it.
What the stage predicts
This is where the test earns its place, and several studies point in one direction. Read the ranges as well as the numbers, because some of the ranges here are very wide. One study followed 94 people with systemic sclerosis for three years.
An active pattern at the start predicted a combined bad outcome at an odds ratio of 3.305, at P equals 0.043. A late pattern predicted it at 6.900, at P equals 0.023. That outcome meant lung function falling, skin score worsening, a first finger ulcer, or death.
One study followed 86 people, where a late pattern predicted finger ulcers at an odds ratio of 6.03 from 1.52 to 23.86. It predicted calcium deposits in the tissues at 27.22 from 5.56 to 133.33, and after adjusting for disease duration and sex that figure came out at 42.89 from 5.53 to 332.85. Read the range rather than the number there, because 5.53 and 332.85 are very far apart.
One study followed 36 people for five years. Of those, 19 developed new finger ulcers, and a late pattern predicted that at a hazard ratio of 7.087 from 1.989 to 25.246. That interval is narrower than most on this page, which makes it one of the firmer findings here.
One study followed 387 people, where having two or more finger ulcers went with the late and active patterns at odds ratios around 2 to 2.6. A skin thickening score above 15 went with them far more strongly, at 32.007 and 18.390. That's a much bigger effect than the ulcer counts showed.
Watching it change
The test gets repeated over time, and the change between one look and the next holds its own information. That makes a second look considerably more than a repeat of the first. One study re-examined 34 people with early systemic sclerosis after three years, and 8 of them, or 23.5 percent, had progressed to definite disease.
The capillaroscopy measures had worsened in 55.9 percent of the group overall. Two specific changes separated those who progressed from those who didn't. More giant vessels came in at P equals 0.02, and a worsening loss score at P equals 0.002.
On multivariate analysis, one thing independently predicted going on to definite disease, and that was an active or late pattern at the start. The odds ratio was 30.0, with the true value somewhere from 2.1 to 421.1. That range is vast, which is what 34 people gives you, though the direction has since been found repeatedly.
One more study makes a quieter point that's worth having. When infusions were interrupted during a pandemic quarantine, lower capillary density predicted whose Raynaud's got worse. Each one-unit rise in density went with a 44 percent fall in the odds of worsening, at 0.56 from 0.36 to 0.97.
Common misconceptions.
Myth. An abnormal result means I have scleroderma.
Reality. It doesn't, because the scleroderma pattern turns up in other illnesses too. One study of 759 people found it in 88 percent of those with systemic sclerosis and in 71 percent of those with mixed connective tissue disease. It also showed in 33 percent with Sjogren's, 17 percent with lupus, and 13 percent with rheumatoid arthritis, and its positive predictive values were low.
Myth. A normal result doesn't tell you much.
Reality. It tells you more than an abnormal one does, which is the unusual part of this test. In that study the absence of a scleroderma pattern was correct 88 percent of the time, and that's the direction this test is strong in. If you've been sent for it because of cold, color-changing fingers, a normal result is the most reassuring thing it can give you.
Myth. All the features they look at count alike.
Reality. They don't, and one study ranked them against each other. Capillary loss separated the groups best at 0.905, with widened vessels next at 0.863 and giant vessels at 0.835. Tiny bleeds managed 0.720 and branching vessels 0.604, which is close to useless, so how many vessels have gone counts for more than how odd the survivors look.
Myth. It's just a snapshot of today.
Reality. It predicts things, and one study followed 34 people with early disease for three years to show it. An active or late pattern at the start predicted going on to definite systemic sclerosis, at an odds ratio of 30.0 from 2.1 to 421.1. That range is enormous, which is what 34 people buys you, though the direction has been found repeatedly.
Myth. It's only useful in systemic sclerosis.
Reality. It turns up in other illnesses too, and one study looked in an unexpected place. It followed 41 young people with childhood-onset lupus, and small vessel damage showed in 68.3 percent of them, with a scleroderma pattern in 7. None of those 7 had any scleroderma symptoms, and large bleeds went with disease activity scores and with kidney involvement.
Related terms.
- Systemic sclerosis, where this test counts for most.
- Raynaud's, the symptom most people are sent for it with.
- Raynaud's compared with poor circulation, for the question this test helps answer.
Questions patients ask.
What happens?
A drop of oil goes on the skin at the base of your fingernail, and then a magnifier or a small video camera looks at it. Several of your fingers get checked one after another. It takes minutes, nothing goes into you, and it doesn't hurt. The vessels being looked at are the smallest in your body, and that skin is one of the few places you can see them.
Why my fingernails?
Because the vessels there run flat, lying parallel to the skin rather than looping away from it. That makes them visible end to end when you look down at them from above. Almost nowhere else on the body lets you see one small vessel whole, and nothing has to be cut to do it. The site of the test is no accident, and that's worth knowing before somebody chooses your hand.
What are they looking for?
Four things, and the four of them don't count equally. Whether vessels are missing, whether the ones left are widened, whether any are so enlarged they count as giants, and whether there's been bleeding around them. One study ranked those measures, and how many vessels have gone separated the groups best, at 0.905.
What does a normal result mean?
It's genuinely reassuring, and reassurance is where the real strength of this test lies. In one study of 759 people with Raynaud's, the absence of a scleroderma pattern was right 88 percent of the time. It doesn't close every question that could be asked. It does make the most feared answer much less likely, which is usually the reason somebody was sent in the first place.
What does an abnormal result mean?
It's the start of a conversation rather than the end of one. An abnormal pattern turns up in several illnesses, and one study found it in 88 percent of people with systemic sclerosis, 71 percent with mixed connective tissue disease, 33 percent with Sjogren's, 17 percent with lupus, and 13 percent with rheumatoid arthritis. Positive predictive values were low in that study.
What do early, active, and late mean?
They're the three stages of the scleroderma pattern, and they run in that order. Early shows a few giant vessels and bleeds with normal numbers, active shows more of both with vessels starting to disappear, and late shows heavy loss with odd branching vessels filling in. Which stage you're in holds real information, so it's worth asking.
Does the stage predict anything?
Yes, and this is where the test earns its place. In 94 people with systemic sclerosis, an active pattern predicted a bad three-year outcome at an odds ratio of 3.305, and a late pattern at 6.900. In 86 others, a late pattern predicted finger ulcers at 6.03 and calcium deposits at 27.22.
Will I need it repeated?
Often, and the changes between one look and the next hold their own information. One study re-examined 34 people with early disease after three years, and the measures had worsened in 55.9 percent. More giant vessels and more loss were both commoner in those whose disease progressed, at P equals 0.02 and P equals 0.002. So a second look is more than a repeat of the first.
References.
- van Roon AM; Huisman CC; van Roon AM et al. Abnormal Nailfold Capillaroscopy Is Common in Patients with Connective Tissue Disease and Associated with Abnormal Pulmonary Function Tests. J Rheumatol. 2019;46:1109-1116. 10.3899/jrheum.180615Journal Article
- Bournia VK; Kottas K; Panopoulos S et al. Differential performance of nailfold video capillaroscopic parameters in the diagnosis and prognosis of systemic sclerosis. Clin Exp Rheumatol. 2020;38 Suppl 125:29-39. PMID 31969216Cross-sectional diagnostic study with follow-up
- Zumstein Camargo C; Kayser C. Capillaroscopy changes are associated with disease progression in patients with early systemic sclerosis: A prospective study. Int J Rheum Dis. 2019;22:1319-1326. 10.1111/1756-185X.13592Prospective study of 44 patients with early systemic sclerosis by LeRoy and Medsger 2001 criteria
- Martins A; Pimenta S; Oliveira D et al. Can microvascular damage predict disease severity in patients with systemic sclerosis?. Reumatol Clin (Engl Ed). 2024;20:366-371. 10.1016/j.reumae.2024.07.006Retrospective study of 86 patients with systemic sclerosis who had nailfold videocapillaroscopy within 6 months of diagnosis
- Boulon C; Aiouaz S; Blaise S et al. Correlation between capillaroscopic classifications and severity in systemic sclerosis: results from SCLEROCAP study at inclusion. Clin Exp Rheumatol. 2019;37 Suppl 119:63-68. PMID 31172926Multicentre prospective study
- Colalillo A; Vaiarello V; Pellicano C et al. Color Doppler Ultrasonography of digital arteries and digital ulcers development in systemic sclerosis. Microvasc Res. 2021;138:104210. 10.1016/j.mvr.2021.104210Comparative study of 36 patients with systemic sclerosis examined by both nailfold videocapillaroscopy and colour Doppler ultrasound of the proper palmar digital arteries
- Schonenberg-Meinema D; Bergkamp SC; Nassar-Sheikh Rashid A et al. Nailfold capillary abnormalities in childhood-onset systemic lupus erythematosus: a cross-sectional study compared with healthy controls. Lupus. 2021;30:818-827. 10.1177/0961203321998750Cross-sectional study of 41 patients with childhood-onset systemic lupus erythematosus against 41 healthy controls matched for ethnic background
- Sebastiani M; Triantafyllias K; Manfredi A et al. Nailfold Capillaroscopy Characteristics of Antisynthetase Syndrome and Possible Clinical Associations: Results of a Multicenter International Study. J Rheumatol. 2019;46:279-284. 10.3899/jrheum.180355Multicentre international retrospective study of nailfold videocapillaroscopy images from 190 patients with antisynthetase syndrome
- Binda M; Moccaldi B; Tirelli F et al. Nailfold videocapillaroscopy in the assessment of juvenile connective tissue diseases. Clin Exp Rheumatol. 2026;44:582-588. 10.55563/clinexprheumatol/6bz7okNailfold videocapillaroscopy in children followed at one paediatric rheumatology unit
- De Lorenzis E; Natalello G; Verardi L et al. Sudden winter iloprost withdrawal in scleroderma patients during COVID-19 pandemic. Microvasc Res. 2022;144:104404. 10.1016/j.mvr.2022.104404Survey of 50 systemic sclerosis patients who stopped intravenous iloprost infusions during COVID-19 quarantine
This page gathers the published research on this subject into one place. The studies behind it were published between 1989 and 2026, and every figure links to the paper it came from. Those studies were peer reviewed. This summary of them was not. Dr. Sarah Luebker is reviewing these pages one at a time and has not reached this one yet, so it carries no medical review date and nothing here is her opinion or her advice to you. Each page gets updated as she reaches it. It is here in the meantime because the science is worth having in one organized place that is easy to find and easy to read. Talk to your own clinician before acting on any of it.