A stasis ulcer is an open wound on the lower leg caused by poor blood flow in the veins. It’s the most common type of leg ulcer, typically forming near the inner ankle where venous pressure is highest. These ulcers develop when damaged or weakened veins can’t push blood back up to the heart efficiently, leading to a buildup of pressure that eventually breaks down the skin.
How Stasis Ulcers Form
Veins in your legs contain one-way valves that keep blood moving upward against gravity. When those valves stop working properly, blood pools in the lower legs, creating sustained high pressure in the veins. This is called venous hypertension, and it’s the primary mechanism behind stasis ulcers.
The elevated pressure forces inflammatory cells and fluid out of the veins and into the surrounding tissue. Over time, this chronic inflammation damages the skin and the fat layer beneath it. The tissue becomes starved of oxygen and nutrients, growing progressively weaker until even minor trauma can cause a wound that won’t heal on its own. Valve dysfunction, blood clots that block outflow, and weak calf muscles (which normally help pump blood upward) all contribute to this process.
What a Stasis Ulcer Looks Like
Stasis ulcers are typically shallow, irregularly shaped wounds that appear on the inner ankle or lower calf. They often look different from a cut or scrape because the wound bed is moist and the edges are uneven rather than clean.
The skin around the ulcer usually shows telltale signs of long-standing venous problems. Early on, the skin of the ankles and lower legs may appear thin or tissue-like. As the condition progresses, you may notice brown or dark discoloration caused by iron deposits from leaking red blood cells. The skin can become thickened and hardened, sometimes taking on a bumpy, cobblestone-like texture. In some cases, the surrounding area looks red, swollen, or weepy, especially if you’ve been scratching irritated skin.
These surrounding skin changes often appear weeks or months before an actual ulcer opens, which is why they’re worth paying attention to early.
Who Is Most at Risk
Several factors raise your chances of developing a stasis ulcer:
- History of deep vein thrombosis (DVT): blood clots damage the valves inside veins, often permanently
- Varicose veins or spider veins: visible signs that venous pressure is already elevated
- Obesity: extra weight increases pressure on leg veins
- Sedentary lifestyle: sitting or standing for long periods without movement weakens the calf muscle pump
- Older age: vein walls and valves weaken over time
- Smoking: impairs circulation and slows wound healing
- Previous leg injury or surgery: including joint replacements
- Family history of venous disease
Having more than one of these risk factors compounds your likelihood significantly. Someone who is overweight, has a desk job, and had a DVT years ago faces a much higher risk than someone with just one of those factors.
Stasis Ulcers vs. Other Leg Ulcers
Not every leg wound is a stasis ulcer. Arterial ulcers and diabetic ulcers look and behave differently, and telling them apart matters because the treatments are very different.
Arterial ulcers form when arteries can’t deliver enough blood to the legs. They tend to appear on the toes, heels, outer ankle, or the front of the shin, and they hurt more than stasis ulcers. The pain typically worsens at night or when the legs are elevated, which is the opposite of venous ulcers, where elevation brings relief. Pulses in the foot are weak or absent with arterial ulcers, while they’re usually normal with stasis ulcers.
Diabetic ulcers develop at pressure points on the bottom of the foot, particularly under the ball of the foot or the heel. Because nerve damage (neuropathy) is often involved, these ulcers are frequently painless, which means people sometimes don’t notice them until they’re well established. Foot pulses are usually present.
Stasis ulcers fall somewhere in the middle on the pain spectrum. They cause some discomfort that gets worse when your legs hang down and improves when you elevate them. Their location near the inner ankle, combined with the characteristic skin discoloration around them, is often enough to distinguish them from the other types.
How Stasis Ulcers Are Diagnosed
A visual exam of the wound, surrounding skin, and overall leg condition gives a strong initial picture. The brown skin discoloration, thickened tissue, and location near the inner ankle point toward a venous cause. But confirming the diagnosis often involves a simple, painless test called the ankle-brachial index (ABI).
The ABI compares blood pressure in your ankle to blood pressure in your arm. A normal result falls between 1.0 and 1.3, which suggests your arteries are healthy and the ulcer is venous in origin. A reading between 0.7 and 0.9 indicates mild arterial disease, while anything below 0.4 signals severe arterial problems. This test is especially important because it determines whether compression therapy, the main treatment for stasis ulcers, is safe to use. Compressing a leg with significant arterial disease can cut off blood supply and make things worse.
Treatment: Compression Is the Foundation
Compression therapy is the cornerstone of stasis ulcer treatment. By applying steady, graduated pressure to the lower leg, compression bandages or stockings counteract the pooling of blood, reduce swelling, and help the wound heal.
Several types of compression systems exist. Multi-layer bandages wrap the leg in several layers that work together to maintain consistent pressure. An Unna boot, a bandage soaked in a zinc-oxide paste, costs roughly $10 per dressing and can be applied in a primary care office. It’s changed weekly and provides both compression and a moist healing environment. Compression stockings are another option, particularly for long-term maintenance after a wound has closed.
Beyond compression, keeping the wound clean and moist with appropriate dressings supports healing. Elevating your legs above heart level several times a day helps reduce the venous pressure that caused the ulcer in the first place. Walking and calf exercises also improve the muscle pump that pushes blood upward, so staying active within your comfort level is important.
For ulcers that don’t respond to compression and wound care, procedures to treat the underlying vein problems may be considered. These target the damaged veins directly, either by sealing them shut or removing them, to reduce the pressure feeding the ulcer.
How Long Healing Takes
Stasis ulcers heal slowly compared to other wounds, and setting realistic expectations matters. Research tracking outpatient compression treatment found that 57% of venous ulcers healed within 10 weeks and 75% healed by 16 weeks. Smaller ulcers do significantly better: those under 20 square centimeters with healthy arterial circulation healed in a median of 7 weeks. Overall, 96% of ulcers healed within one year.
Larger ulcers and those complicated by arterial disease take considerably longer. The key variables are ulcer size at the start of treatment, how well blood flows through your arteries, and how consistently you use compression. Skipping compression or spending long hours sitting with your legs down can stall progress dramatically.
Preventing Recurrence
Stasis ulcers have a high recurrence rate. The underlying vein damage doesn’t go away when the wound closes, so the same pressures that caused the first ulcer can open a new one. Wearing compression stockings daily, even after healing, is the single most effective way to prevent a new ulcer from forming. Staying physically active, maintaining a healthy weight, elevating your legs when resting, and avoiding prolonged standing or sitting all help keep venous pressure in check.
Monitoring the skin on your lower legs is also valuable. If you notice the early warning signs, such as new brown discoloration, skin thickening, swelling, or itchiness around the ankles, those changes signal rising venous pressure and a chance to intervene before the skin breaks down again.