Pitfalls in obtaining and interpreting bone marrow aspirates: to err is human.

Pitfalls relating to bone marrow aspirates and their interpretation start even before the aspirate is obtained. There can be failure to perform an aspiration that is clinically indicated or, conversely, an aspiration may be done that is not actually necessary. Once an aspirate is obtained it may be unhelpful because it is a blood tap or very dilute, or because of the sampling error that is intrinsic to the procedure. Even if an adequate aspirate is obtained, it may be misinterpreted. Megaloblastic marrows and children's marrows with increased haematogones or marked reactive changes are particularly prone to misinterpretation. A constant awareness of potential pitfalls and an assessment of the aspirate in the appropriate clinical context will help to reduce errors.