Hidradenitis suppurativa (HS) is more than skin deep. For people living with HS, the visible lumps, tunnels, and scars are only what you see on the surface. To fully understand HS, you need to look deeper.

Managing HS may require a combination of treatments, including medications, lifestyle changes, and surgery. There’s also a newer tool that’s becoming important in treatment: ultrasound. In this article, we’ll explore how ultrasound can help in diagnosing and treating HS, what it can do for you, and what limitations it might have.

What Is an Ultrasound?

An ultrasound is a medical imaging technique — also known as ultrasonography — that uses high-frequency sound waves to take pictures of the inside of your body. Unlike X-rays, ultrasound doesn’t use radiation, so it’s safer for repeated use. You may have heard of ultrasound because it’s used during pregnancy to check on the developing baby. But ultrasound can also be used to look at muscles, organs, and even the deeper layers of your skin.

For people with HS, ultrasound is particularly useful because it lets doctors see beneath your skin’s surface. The physical symptoms of HS often go deeper than what you can see or feel. Ultrasound can reveal those hidden issues.

Getting an ultrasound examination is painless. First, a trained technician will apply a special gel to your skin. Then, they’ll move a small device, called a transducer, over the affected areas. The transducer uses sound waves to create images of what’s happening beneath your skin. The technician then sends these images to your doctor or a radiologist (an imaging specialist) for review. This helps your doctor see things that aren’t visible to the naked eye.

How Can Ultrasound Help Diagnose HS?

One of the main ways ultrasound is used in HS is to help diagnose the condition. Sometimes, it can be hard for doctors to tell what’s going on just by looking at the skin. Ultrasound helps by detecting lumps and tunnels (sinus tracts) that you might not be able to see or feel. It can also allow your doctor to look at the hair follicles (structures within your skin that grow hair), which are located in the subcutaneous (deeper layers) of the skin. Abnormal changes in the hair follicles can be a subclinical (early) sign of HS that isn’t visible during a regular examination. Ultrasound can also help catch early-stage lesions (areas of diseased skin) that haven’t yet broken through the surface of your skin. Catching these early symptoms can be essential in preventing them from getting worse.

Not all HS lesions are the same. Some are simple nodules (abnormal tissue growths), while others are more complex, like abscesses (inflamed tissue filled with pus) or tunnels. Ultrasound can help your doctor see what type of lesion you have, which can be important for choosing the right treatment.

How Can Ultrasound Assess the Severity of HS?

Understanding how severe your HS is can help your doctor decide the best treatment plan for you. Usually, your dermatologist (skin specialist) will look at your skin and ask about your symptoms to assess your HS. But ultrasound can give a much clearer picture.

Hurley Staging System

The Hurley staging system is a widely used method for classifying how severe the HS is. It divides HS into three stages based on the type and extent of lesions, like nodules, abscesses, scarring, and tunnels.

• Stage 1 — Single or multiple isolated nodules with no sinus tracts or scarring
• Stage 2 — Multiple or returning abscesses that appear with sinus tracts and scarring but are still separated by areas of normal skin
• Stage 3 — Multiple abscesses with connected sinus tracts and significant scarring over large areas

The Hurley system is based on lesions that can be seen on the skin, but it might not fully capture the depth of the disease. Ultrasound provides a detailed view of the skin’s deeper layers. This can reveal hidden lesions and tunnels that aren’t visible on the surface of the skin. For instance, in stage 1, ultrasound can find deeper lesions that suggest the disease is more advanced than it appears. In stages 2 and 3, it can help assess the depth and extent of sinus tracts and abscesses, offering a clearer picture of the disease’s severity.

Ultrasound can be used alongside the Hurley staging system for a more thorough evaluation. It can find nodules, abscesses, and sinus tracts that are not visible during a regular examination. It can also give your doctor a better idea of how much vascularization (blood flow) there is in the diseased areas underneath the skin. This helps your doctor assess disease activity by measuring active inflammation.

Use of Ultrasound With Surgery for HS

For some people living with HS, surgery is a necessary part of treatment, especially if the disease is advanced. Ultrasound can be a helpful tool before and during the procedure.

Before surgery, ultrasound helps the surgeon see exactly where the affected areas are. Ultrasound can help map out the sinus tracts, abscesses, and other lesions under your skin more precisely than a physical examination alone. This will help your surgeon remove as much of the disease as possible, which can reduce the chances of HS coming back in that area.

Sometimes, ultrasound can even be used during the surgery to help guide the surgeon and find all the affected tissue. This can be particularly useful if the HS is in a tricky spot or if the sinus tracts are very deep.

Ultrasound to Track Successful Treatment of Hidradenitis Suppurativa

After you start treatment for HS, your doctor will need to monitor you for signs that it’s working. Ultrasound can help with this too.

Ultrasound can help your doctor see if the lumps, abscesses, or sinus tracts are getting smaller. This can be a good sign that your treatment is working. On the other hand, if things aren’t improving, it might be a sign that you need to try a different type of treatment.

After surgery or other treatments, ultrasound can also help spot other problems, like fluid buildup or new abscesses. Catching new or worsening symptoms early can help prevent more serious issues from developing.

Advantages of Ultrasound in HS

Ultrasound offers several advantages for diagnosing HS and assessing the stage it is in (staging). It allows your doctor to see the full extent of the disease, including lesions that are not visible on the surface. This can make staging more accurate.

Ultrasound also provides real-time images. This means that doctors can immediately see the results and make decisions about staging and treatment during the same visit. Unlike biopsies (tissue samples) or other invasive tests, ultrasound is noninvasive and painless. It can be done as often as needed without significant risk to your health.

Limitations of Ultrasound in HS

As with any medical imaging tool, the use of ultrasound has its limitations. For example, there are still some differences in how ultrasound findings are interpreted. This means that two different specialists can look at the same ultrasound images and draw different conclusions about the results.

Although the use of ultrasound is becoming more common for HS, there are still no standard guidelines on how to use it for staging. This means that different health care providers might use different methods, which could lead to inconsistencies in care. There is a proposed standard for reporting ultrasound results in HS, but it hasn’t been widely adopted yet.

Talk With Others Who Understand

On myHSteam, the social network for people with hidradenitis suppurativa, more than 43,000 members come together to ask questions, give advice, and share their stories with others who understand life with HS.

Has your dermatologist used ultrasound to help diagnose or stage your HS? What was your experience like? Share your experience in the comments below, or start a conversation by posting on your Activities page.