BMA at presentation did not significantly alter the diagnosis in our cohort of patients with an initial suspicion of ITP, although the procedure was decisive in diagnosing 2 cases of acquired aplastic anaemia during the subsequent course of the disease. Regarding the number of aspirations performed, our findings show that increased physician compliance with current guidelines reduced the rate of unnecessary BMAs. • BMA is a supplementary test for the diagnosis of ITP. • The usefulness of this invasive diagnostic procedure is not clearly stated in current guidelines. • Adjustments to scientific guidelines have led to a reduction in the number of BMAs performed on our patients with suspected ITP in the last 27years. • While the risks and benefits of BMA at the time of diagnosis are unclear in patients with suspected ITP, the procedure does not contribute significant information to support the diagnosis.