Kasabach-Merritt phenomenon

The first step in treating your child is forming an accurate and complete diagnosis.

Diagnosing Kasabach-Merritt phenomenon (KMP) can be difficult for many physicians simply because it’s such a rare condition. The specialists at the Vascular Anomalies Center at Children’s Hospital Boston understand how KMP works and so can easily identify it—and begin treatment to help your child get better.

How do I know if my child has Kasabach-Merritt phenomenon?

The only way to diagnose Kasabach-Merritt phenomenon is through a blood test.

• Complete blood count (CBC) — If your child’s doctor suspects Kasabach-Merritt phenomenon, he or she will order a complete blood count to check your child’s platelet level. If it’s low, your child has Kasabach-Merritt phenomenon.

• Often, other laboratory tests related to bleeding are also performed, including prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen and D-dimer. These assess for other bleeding problems often confused with KMP and may be clues about alternative diagnoses.

What are these tests like?

One of the members of your care team (probably a nurse or phlebotomist) will take a little blood from your child and collect it in a small tube. Our lab then analyzes your child’s blood and sends the results to your doctor. If your child’s doctor diagnoses Kasabach-Merritt phenomenon, you’ll learn about your treatment options.

When should I consult a vascular anomalies specialist?

We advise consulting a vascular anomalies specialist in three situations:

• if your child has a vascular skin lesion and a low platelet count
• if your child has a vascular skin lesion that seems to be growing beyond expectations
• if your child has a vascular skin lesion that gets larger, darker and more painful after a platelet transfusion

After we complete all necessary tests, our experts meet to review and discuss what they have learned about your child's condition. Then we will meet with you and your family to discuss the results and outline the best treatment options.