On the surface, many bleeding disorders look the same. Doctors need to order specific tests to diagnose von Willebrand disease (VWD) and rule out other conditions like hemophilia. Getting an accurate diagnosis is the first step to getting the treatment you need.

This article will discuss how VWD is diagnosed, including blood tests and genetic testing. To learn more about the diagnostic process and your risk of VWD, talk to your health care provider or a hematologist (blood specialist).

What Is von Willebrand Disease?

VWD is a genetic disorder that increases a person’s risk of excessive bleeding. This condition occurs because your body has difficulty forming blood clots, making it challenging to stop bleeding once it begins. VWD develops in people who don’t make enough of a specialized protein known as “von Willebrand factor (VWF).”

VWF is an important protein that helps platelets stick together. Platelets are sticky cell fragments made in the bone marrow — the spongy tissue inside your bones. These cell fragments play a key role in forming blood clots. Without enough VWF, a person’s blood takes longer to clot than it normally would. This means they may lose more blood while waiting for a blood clot to form.

How Do Doctors Screen for Clotting Disorders?

If you’re experiencing symptoms of a blood clotting disorder, your doctor will start with a general screening process. This includes a physical exam and simple blood tests. Your test results may suggest that you need more testing for VWD or another condition.

Medical History and Physical Exam

Your doctor will start by taking a complete medical history and physical exam. They’ll ask about your symptoms, which typically include:

• Easy bruising and bleeding
• Frequent nosebleeds that last at least 10 minutes and happen five or more times per year
• Heavy menstrual periods
• Bleeding during dental procedures and after other surgeries
• Blood in your urine or stool (poop)
• Fatigue and shortness of breath, which may result from low red blood cell (RBC) counts due to frequent bleeding

It’s crucial to let your doctor know if you have a family history of VWD. Many blood clotting disorders are genetic and passed down through family members. Having a parent or a sibling with VWD raises your risk of developing it.

During the physical exam, your doctor will look for bruises and other signs of bleeding.

Complete Blood Count

If your doctor suspects you have a bleeding disorder, they’ll likely start by ordering a complete blood count (CBC). This test measures your levels of:

• Red blood cells — Responsible for carrying oxygen throughout the body
• White blood cells (WBCs) — Immune cells that protect you from infections
• Platelets — Sticky cell fragments that play a key role in forming blood clots

These tests are typically normal in people with VWD — the real problem is with missing von Willebrand factor. Your CBC may be abnormal if you’re experiencing heavy bleeding.

Prothrombin Time Test and Activated Partial Thromboplastin Time Test

Blood clotting is a complex process that requires many clotting factors or proteins. Some clotting factors are numbered, and you may see them written with Roman numerals, such as “factor IX (9).”

Blood clots only form when all of these proteins work together. If you’re missing a factor, it may take longer for you to form clots and stop bleeding. Your doctor can order tests to see how quickly your blood forms clots.

There are two main tests — a prothrombin time (PT) test and an activated partial thromboplastin time (APTT) test. Each test measures how well certain blood clotting factors work together. To run a PT and APTT test, a health care provider takes a small blood sample. They put it in a machine to measure your blood clotting time.

A PT test measures the activity of clotting factors:

• I (1)
• II (2)
• V (5)
• VII (7)
• X (10)

On the other hand, an APTT test measures the clotting factors:

• VIII (8)
• IX (9)
• XI (11)
• XII (12)

According to the Centers for Disease Control and Prevention (CDC), most people with VWD will have a normal PT test result. Some people with VWD will have a longer clotting time in the APTT test. However, those with mild VWD typically have normal results.

How Do Doctors Specifically Diagnose von Willebrand Disease?

You may need other, more specific tests to accurately diagnose VWD. Many of these tests measure VWF — including how high your levels are and how well the protein works.

Von Willebrand Factor Antigen

VWF antigen testing measures your levels of VWF protein. People with VWD make different amounts of VWF, which affects how severe the disease is. The lower your VWF levels are, the more severe your VWD symptoms are.

Doctors use VWF antigen testing along with other tests to rule out other bleeding disorders and confirm that you have VWD. For example, a VWF antigen test along with a factor VIII test can help rule out hemophilia A.

Testing for von Willebrand Factor Multimers

VWF is a protein made of small pieces that form large structures known as “multimers.” Doctors can order a VWF multimer test to check the overall structure of the protein. This test helps diagnose which type of VWD you have — specifically type 2 VWD.

People with type 2 VWD have different structures of the VWF protein. Some have multimers that are abnormally large, while others don’t make enough of the correct size. A VWF multimer test can also help your doctor decide your treatment plan.

Ristocetin Cofactor Activity

The von Willebrand ristocetin cofactor (VWF:RCo) test is another way doctors measure your blood’s ability to form clots. Specifically, this test looks at how well your platelets stick together with ristocetin. Your platelets need enough VWF to work properly.

Clotting Factor Activity Testing

Your doctor may also check your factor VIII levels when diagnosing VWD. The VWF protein protects the factor VIII proteins found in your blood. The ratio of VWF to factor VIII can help determine which type of VWD you have. The lower the ratio is, the more severe your VWD is.

Genetic Testing

VWD is a genetic disease that’s passed down through family members. Most of the time, VWD is inherited as an autosomal dominant disease. This means that even if one parent is affected, there is a 50 percent chance they can pass the disease on to their children. Rarely, type 3 VWD is inherited in an autosomal recessive form, which means that both parents need to pass on mutated genes for their children to express the disease. This form of VWD is much more severe than the more common autosomal dominant forms.

VWD develops in people with changes or mutations in the VWF gene. Genetic testing looks for these mutations. Some people can be “carriers” of VWD, which means they have one mutated copy and one healthy copy of the VWF gene. Family members of those with VWD can get genetic testing to find out if they’re carriers. This helps people understand the risk of passing the disease on to their children.

Talk to Your Doctor About von Willebrand Disease

To learn more about VWD and how it’s diagnosed, talk to your doctor. They can also offer more information about treatments and precautions you can take while living with the disease.

Talk With Others Who Understand

On MyHemophiliaTeam, the social network for people with hemophilia and their loved ones, more than 6,600 members come together to ask questions, give advice, and share their stories with others who understand life with hemophilia and other bleeding disorders.

Have you or a loved one been diagnosed with von Willebrand disease? What tests helped confirm the diagnosis? Share your experience in the comments below, or start a conversation by posting on your Activities page.