How to differentiate between arterial, venous, and diabetic ulcers

26th Feb 2021

Discerning the cause of a patient’s foot or lower leg ulcer can be difficult. However, there are ways to differentiate between arterial, venous, and diabetic ulcers. This is great news since ordering arterial and venous insufficiency studies for every wound is expensive and a waste of resources.

Sometimes the cause of an ulcer is a combination of arterial disease, venous disease, and diabetes. However, ulcers often have one primary cause, and there are ways to tell these types of ulcers apart.

There are three steps to follow when you begin to evaluate a patient with a foot or lower leg ulcer:

  1. Check pedal pulses
  2. Ask if the wound is painful
  3. Inspect the ulcer 

 

Step 1: Check pedal pulses

Start your evaluation with a pedal pulse check. You can begin the check with manual palpation. Ideally, you’ll want to check for a pulse with a Doppler pen, especially if you can’t manually palpate the pulses. 

If the pulses sound strong in volume and you can hear two or three separate sounds (e.g., phases) per pulse, the arteries are patent. This means that the wound is not due to arterial limb ischemia, and you can move on to venous disease and diabetic ulcer differentiation.

The waveform sounds from the Doppler will also give you a general idea of the presence or absence of peripheral arterial disease (PAD). 

 

Step 2: Ask if the wound is painful

Typically, arterial ulcers are extremely painful. Venous ulcers can present with dull and achy pain in the entire leg, but the wound area itself usually doesn’t hurt unless it’s infected. Diabetic ulcers may present with the pins-and-needles pain or a loss of sensation that is associated with peripheral neuropathy.

 

Step 3: Inspect the ulcer

It’s also important to inspect the ulcer and note the border, depth, and location. A quick trick to watch for is that arterial and diabetic ulcers look alike and occur in tandem, but venous ulcers are usually identified by clinical examination. 

Hand palpating pedal pulses, question mark surrounded by jagged red lines to represent pain, foot with a magnifying glass inspecting an ulcer. Illustration.

Figure 1. The steps for evaluating a foot or leg ulcer include, 1) check pedal pulses, 2) ask if the wound is painful, and 3) inspect the ulcer.

Now, let’s get into more detail on how to differentiate between the three types of ulcers.

 

Signs and symptoms of arterial ulcers

Typically, arterial ulcers are extremely painful. However, it’s important to remember that patients who also experience peripheral neuropathy may not feel them at all. 

Chronic arterial ulcers look like deep, round hole punches with regular, well-defined, raised borders. The area around the ulcer will feel dry and cold and the skin may be cracked. The pedal pulses will be weak or absent. 

Arterial ulcers are mostly located on the toes, between the toes, around the lateral ankle, or on the tibia. Severe late-stage arterial ulcers can present as gangrenous chronic limb ischemia (CLI) involving the toes. 

Chronic arterial ulcers are due to arteries that are slowly blocked over time. These ulcers are usually seen in older adults. The progressive blockage of the arteries decreases blood flow to an area which causes the tissue to die. The pain that is associated with these arterial blockages can be improved by dangling the leg, which increases blood flow to the area.

Not all people with severe peripheral arterial disease (PAD) have ulcers! The slow process of plaque buildup allows for the development of collateral arteries, which are new arterial branches that can provide additional blood flow to the area. Identifying the presence of collateral flow can help you decide the need for an intervention. Medmastery note.

Illustration of a foot with an arterial ulcer that is round and well-defined. Ultrasound showing plaque buildup in an artery.

Figure 2. Arterial ulcers are typically deep with round, regular, and well-defined borders. On ultrasound, you can visualize plaque buildup within an artery that has led to the appearance of a chronic arterial ulcer. 

If you suspect an arterial ulcer based on clinical findings and the patient’s presentation, order an ankle-brachial index (ABI). Medmastery note.

Signs and symptoms of venous ulcers

Most lower extremity ulcers are venous ulcers. These ulcers are due to weak valves in the veins which create increased pressure in the leg tissues. They are associated with edema, varicose veins, and scaly alligator-like skin. 

Chronic venous ulcers weep fluid and have irregular, shallow borders. Some patients note that their socks or pant legs are wet from unwrapped wound discharge. 

Venous ulcers are generally located in the distal medial calf and ankle. Arterial pedal pulses will be strong. But, don’t be fooled! The pulses may be difficult to find if the patient has edema. 

Pain caused by venous ulcers is a dull, achy pain that is improved by elevating the leg, as opposed to dangling, like in arterial blockages. 

Foot with a venous ulcer that is irregular, shallow, and weeping fluid. Illustration.

Figure 3. Venous ulcers typically weep fluid and have irregular, shallow borders.

If you suspect a venous ulcer, a venous insufficiency ultrasound should be ordered, not an arterial ultrasound. Medmastery note.

Signs and symptoms of diabetic ulcers

Diabetic ulcers are caused by hyperglycemia. Notably, most nontraumatic amputations are due to diabetic ulcers. 

The borders of diabetic ulcers are usually raised and round. They are often located on the bottom of the feet and are associated with skin cracks, blisters, and sores. They appear red and warm in the earlier stages and then progress to eschar and gangrene in the later stages. 

Patients with diabetes frequently present with peripheral neuropathy (pins-and-needles pain or total loss of sensation) due to nerve damage. The patients will also have strong pedal pulses, and their arterial and venous tests are typically normal. 

Remember, strong pedal pulses are usually present with venous or diabetic ulcers, whereas weak or absent pedal pulses are present with arterial ulcers. This is an extremely important differentiation that can be determined at the beginning of the exam. Medmastery note.

Illustration and image of plantar aspect of a foot with a raised, round, diabetic ulcer.

Figure 4. Diabetic ulcers typically occur at the bottom of the foot and are usually raised and round. 

You can quickly differentiate all three ulcer etiologies by comparing their clinical presentations.

Table summarizing the typical pedal pulse, pain, and inspection findings with arterial, venous, and diabetic ulcers.

Table 1. Summary of typical findings with arterial, venous, and diabetic ulcers.

 

How to tell if a patient with diabetes also has arterial CLI

A patient with diabetes can have diabetic ulcers in conjunction with arterial CLI. Thus, if the patient’s pulses are weak and the wound has arterial CLI characteristics, it warrants a quick ABI test. 

If the pulses are bounding, the arterial ultrasound will likely reveal arterial wall calcification rather than atherosclerosis. Arterial wall calcification will show up as black acoustic shadowing on ultrasound. Depending on which wall the plaque is on, the shadowing can happen over the whole artery (if on the anterior wall), or under the artery alone (if on the posterior wall).

Arterial wall calcification with typical black acoustic shadowing over the artery. Ultrasound image.

Figure 5. Arterial wall calcification can be identified on ultrasound by the appearance of black acoustic shadowing either over the whole artery or under the artery alone. 

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