After you receive a bone marrow or cord blood transplant (also called a BMT), your transplant team will watch for signs of engraftment. Engraftment is when the donated cells you received for your transplant start to grow and make new blood cells.
You will have daily blood samples taken while you are waiting for your donated cells to engraft. The blood samples will be given a complete blood count (CBC) test. A CBC test can give your doctors information about the kinds and numbers of healthy cells in the blood. The types of blood cells that are counted to measure engraftment are neutrophils, which are a type of white blood cell that are important for fighting infections, and platelets, which help control bleeding.
Neutrophil engraftment
A CBC test counts the number of neutrophils in your bloodstream. An absolute neutrophil count (ANC) of 500 or more for 3 days in a row is a sign of engraftment. This means that the blood test shows 500 or more neutrophils in a cubic millimeter of blood. Neutrophil engraftment can occur as early as 10 days after transplant. About 20 days is more common for patients who receive marrow or peripheral (circulating) blood cells. For patients who receive cord blood, the average time to neutrophil engraftment is between 21 and 35 days.
Platelet engraftment
A CBC test will also show the number of platelets in your bloodstream. A platelet count of 20,000 to 50,000 is a mark of platelet engraftment. This means your blood test shows 20,000 - 50,000 platelets per microliter of blood. For patients who receive marrow or peripheral blood cells, platelet engraftment often happens at the same time or a little bit after neutrophil engraftment. For patients who receive cord blood, it may be 8 weeks or longer after transplant before platelet engraftment occurs.
Neutrophil — A type of white blood cell
ANC — Absolute neutrophil count
Neutrophil engraftment — ANC count of 500 or more for 3 days in a row
Platelet engraftment — Platelet count of 20,000 - 50,000 (without platelet transfusion)